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A Review of the International Clinical Literature by Sir Aubrey Lewis,

Emeritus Professor of Psychiatry, University of London




Physical Effects

The physical effects of cannabis intoxication are raised pulse rate and blood pressure, dilated sluggish pupils, injected conjunctival vessels, tremor of tongue and mouth, cold extremities, rapid shallow breathing, ataxia and active deep reflexes. The severity of the symptoms depends not only on the dose and preparation but on the individual. A young English-woman on one occasion smoked two-thirds of a home-made hashish cigarette which had not upset her husband; she promptly developed gross incoordination of the hands, astasia, rapid pulse, and dyspnoea. In soldiers who took cannabis a temporary loss of consciousness has been reported with slow irregular pulse and low blood pressure. Others have described vertigo and vomiting, and death is said to have occurred from cardiac failure or intestinal distention after gross overeating. But severe physical disturbance is rare. A common initial effect of smoking the drug is intense cough or burning feeling in the throat and chest.


Psychological Effects

The psychological effects of acute intoxication were first described in detail by Moreau de Tours: euphoria; excitement; disturbed associations; changes in the appreciation of time and space; raised auditory sensitivity with elaboration of simple phrases or tunes: fixed ideas: emotional upheaval; and illusions and hallucinations.

Suggestibility is much increased (the assassination of General Kleber is supposed to have been carried out by a fanatic whose heightened suggestibility under cannabis made him a pliant catspaw).

There are no aphrodisiac effects, in spite of widespread popular belief. Erotic fantasies may be well to the fore, but they do not lead to action.

There is much individual variation in the psychological effects. Perhaps because of ethnic and social differences and the effects of different preparations of the drug, widely divergent accounts are to be found in published papers. Lord Todd put it succinctly: "To give an accurate picture of the effects of hashish is extremely difficult, partly because they are more subjective than objective and because individual variation in response is probable greater with this than with any other drug.... Among the commonest recorded effects are the feeling of well-being alternating with depression, distortion of time and space, and double consciousness. Objectively there is a period of excitation and exaltation, followed often by sleep or coma".

Some subjects feel acute anxiety as soon as the drug takes effect; others are pleased, amused, elated, although they may be aware that their thought processes are somewhat disordered, their memory impaired and their self-control diminished. The phases of abnormality might come in waves, heralded by sudden violent headaches. The emotional state is not in keeping with the subject’s situation, and as the intoxication grows less, subjects mostly feel apathetic and depressed. During the acute stage of intoxication they may have become suspicious and afraid that they will be permanently insane, or that their friends are trying to find grounds for shutting them up in a mental hospital. Characteristic visual phenomena are almost invariably reported; they are not true hallucinations but illusionary falsification, greatly elaborated by some subjects. Perception of one’s own body is commonly interfered with and outright depersonalization may occur. With small doses of cannabis the effect may be wholly subjective, mild and gratifying.

The first signs of intoxication, appearing about three hours after consuming the drug by mouth may be nausea or vomiting, with gross movements and loquacity. Disorders of thinking may be overt, or detectable by close examination. Intoxicated persons may be unable to retain more than a single sentence so that conversation is disjointed and may be unintelligible; a communication that has been heard and understood may be lost in a few seconds; in the middle of a lively conversation, speech may stop abruptly and the intended remark is gone beyond recovery. The disturbance of memory may be severe in one person and negligible in another. The time schedule varies according to the mode of consumption. After smoking hashish resin, acute anxiety and restlessness may come on within about half-an-hour; then calm and pleasant sensations supervene with visual imagery; and in one to two hours the subject becomes sleepy; when be wakes from the ensuing sleep he may be able to recall details of the intoxication. If, however, he has taken the cannabis in powder form it may take three to six hours for sleepiness to come on.

In Europeans, though the order of events may vary a great deal, a typical sequence is eupnoria with restlessness; then confusion, disturbed visual and auditory perception; then a dreamy state; and finally depression and sleep. On waking after this sleep, there may be numbness, dysarthria and some amnesia. Many Moroccans, when under the influence of the drug, become gay or relaxed, though it is not rare for anger to be expressed in some act of violence. According to one observer, they value cannabis because it frees them temporarily from moral and cultural restraints on conduct. In contrast to the torpor described in some subjects, the Moroccans may feel that they can do difficult things easily, and they may jump and dance. Hesnard, a psychiatrist who has observed Turkish and Syrian hemp addicts, described them as incoherent in speech but self-observant; talkative, exuberant, gesticulating and running hither and thither, but incapable of mental work, and agitated. Noisy laughter may be incongruously accompanied by sadness. Intense depersonalization sometimes occurs.

They have erotic desires which they do not translate into erotic behaviour. In Brazil, according to Wolff and other Brazilian psychiatrists, the picture is different from that described elsewhere; sexual orgies are alleged to take place.

The discrepancies in published accounts of acute intoxication may be, in part, accounted for not only by individual constitution and the effect of adulterants, but also by differences in dosage. Practised hashish consumers have usually learned how to regulate the dose of whatever preparation they use so that the disagreeable effects are minimal.


Psychotic Features

Among the symptoms of acute intoxication, gross mental disturbances are described which can properly be called psychotic. They are usually the outcome of taking a fairly large dose of the drug; and the clinical picture is that of a severe exogenous psychosis delirium with confusion, disorientation, terror or anger, and subsequent amnesia about what happened during the period of intoxication. Although most often described in countries where cannabis is widely resorted to, striking instances are reported also in Europeans.

Within this acute setting, the most frequent psychotic features are: paranoid delusions of being pursued or controlled: delusions of preternatural abilities; strong inclinations to suicide which are not carried into action unless associated with panic: and irritability. Waxy flexibility and other catatonic features have been observed. though infrequently.

The impulse to suicide may be very strong; a doctor who took forty drops of tincture of cannabis indica developed at first great anxiety and fear of death, then ‘’I was possessed with an almost irresistible desire to commit suicide by rushing to the adjoining canal or cutting my throat with the knives on the table close by, though no attempt was made at doing so. Shortly upon this, I was seized with fits of alternate laughter and crying, without any apparent cause. When the symptoms were subsiding my appetite became ravenous accompanied by great thirst.... I experienced no pleasurable intoxication or feeling of happiness. but the very reverse".

There is a sharp contrast between the ecstatic and relaxed state described in many reports and the restless activity occasionally observed (along with exaltation, irritability, emotional excess, noisiness and even reckless violence) in some subject’s, especially in the Punjab or in Brazil. Evidently, large doses produce anomalous effects, seldom seen in mentally stable persons or in those who have learned to regulate their intake so that it should be pleasurable. An example of how excess can affect the individual is provided by a French youth aged 20 who smoked five hashish cigarettes straight off. He became very agitated and restless, rushed around Pans and eventually, fourteen hours after he had taken the drug, he went into a police station to give himself up for having murdered his step-father (an entirely baseless delusion). The duration of the psychotic intoxication was longer in his case than is usual; as a rule, the condition clears up in three to six hours.

Exact psychological studies of the effects of cannabis have suffered from the limitation that they were carried out either on highly selected subjects - prisoners and drug addicts - or on very small samples, sometimes only two or three persons. The main findings have been that simple functions like tapping speed and reaction time were very little affected by moderate doses of cannabis, but that steadiness of hand movements and complex reaction time were adversely affected, the maximum change occurring about four hours after ingestion.

In intellectual tasks speed and accuracy were impaired, the degree depending on the dose. Surprisingly, the ability to estimate short periods of time was not reduced in an American study, but the subjects were chronic addicts; whereas in an experiment carried out by two psychiatrists on each other, under laboratory conditions. time intervals were overestimated. Two German psychiatrists examined thirty normal subjects, and found three types of intellectual disorder - incapacity to fuse details into a whole; reduced memory storage; and blocking; these observations were made, however, after the drug had been administered in the form of cannabinol 0.1 g.


Effects on Persons already Pschotic

In the 1930’s experiments were carried out on schizophrenic and depressed patients in mental hospitals to see what cannabis would do to them and how far the drugs, alleged to be psychotomimetic, would intensify psychotic symptoms. The findings were not uniform. Affectivity was altered but in different ways and degrees; some schizophrenics became euphoric and hyperactive, others became catatonic; surprisingly, only two-thirds of the schizophrenics developed hallucinations. Some of the depressed subjects became euphoric, others passed into a depressive stupor. Autism was intensified in some schizophrenics and symptoms that had previously cleared up were revived. The schizophrenic patients showed less change in time and space perception than normal subjects while under the influence of the drug. Impulsive acts were more prone to occur in schizophrenic subjects than in normal cannabis users.



Initiation: Social Setting

Most of those who take cannabis in any society have been introduced to the habit by an acquaintance. The amount of pressure varies from country to country - the commoner the habit, the more ready the compliance - and from group to group. In Egypt (where penalties are severe and include capital punishment for trafficking), the habit is nevertheless very widespread; and, as was shown by a recent investigation on 253 men who had used hashish at least once a month during the previous year, conformity to the ways of the group emerges as a powerful factor, especially among those who have been led to expect a blissful experience and sexual stimulation from it. Taking it is a convivial affair; four to six friends meet in the evening, smoke and engage in light conversation. Similarly, an American report confirmed the view that marihuana is a socially utilized intoxicant, seldom taken in solitude. Those who have studied American college students who smoke marihuana conclude that they do so because they are alienated from the values of adult society. which exposes them to conflicting demands; through this habit they can mortify their parents and flout authorities. This is a speculative interpretation of their motives.

The fullest available description of the social conditions which foster the marihuana habit comes from Oakland, California. It counterbalances, and perhaps corrects, the picturesque and alarming observations made on more degraded, psychopathic, criminal, or poverty-stricken and under-nourished groups. The investigators obtained the confidence of the youngsters, mostly Negroes and Mexicans, through providing them with club amenities, without strings. They were firm in their convictions based on their own experience, that the use of such drugs as marihuana results in harmless pleasure and increased conviviality, does not lead to violence or madness. can be regulated, does not lead to addiction, and is less harmful than alcohol. They were not interested in being helped to abstain from marihuana, and they cited case after case of individuals known to them who had not suffered deterioration in health, school achievement, athletics or career as a result of their habit of smoking marihuana. Boys who take the drug in excess were considered by the rest to have a weak personality.

There are several patterns of use and users among these youths. They themselves recognize four types, for which they have cant names. The "rowdy dude" Wants to impress and frighten others and has difficulty in getting marihuana from other youths because he is reckless and irresponsible and they fear he will get them into trouble with the police: he is subject to pressures which direct him towards becoming a criminal or an opiate addict. The "rowdy dude" may settle down, when he stops taking alcohol or sniffing glue, and starts to take marihuana instead. In that case he becomes a "pot head" who limits himself to marihuana smoking. or a "mellow dude" who uses amphetamines or barbiturates or methedrine as well as marihuana. Both the "pot heads" and the "mellow dudes" value sang-froid. They believe themselves to be intelligent, daring, cool-headed, worthy of respect, and they do not resort to violence they remain at school or at work and engage in athletics. They will smoke marihuana three or four times a day, especially if they are going to a party; they believe it breaks through their shyness in approaching girls and increases the pleasure of sexual intercourse. Thc fourth type is the "player", an older youth who sells drugs and becomes a violent criminal or a pimp or fence; he may take to heroin but will mostly be on his guard against any drug that may reduce his alertness.

Initiation into marihuana-smoking in this group is usually effected through the desire to emulate older boys. The Oakland investigators reject firmly the usual assumption, that those who take to the habit are mainly influenced by emotional disturbances and social stresses. Their observations do not support the explanation which regards marihuana use as an effort to escape from reality or to vent underlying hatred of organized society. They conclude that "induction into drug use is a developing experience that depends on access to drugs, acceptance by drug-using associates and kinds of image that youngsters have of drugs". So far from retreating from reality, marihuana-users are held to be making a positive effort to be in the mainstream. The investigators likewise reject the notion of a steady progression from marihuana to crime and opiate addiction. It may occur, as the four types indicate, but most users steer away from these courses. Many of the Oakland youths had experimented with heroin, but only four had become addicts.

The summary conclusion by the Oakland observers is unequivocal: "Youthful drug use in Oakland is an appreciable extensive and deeply rooted practice, lodged primarily in the lower strata but currently expanding into middle and upper class strata. It is woven into a round of adolescent life as a collective practice . . . and is buttressed by a body of justifying beliefs and convictions, involves a repertoire of practical knowledge and incorporates a body of precautions and protections against apprehension or arrest. Drug use constitutes for the users a natural way of life and does not represent a pathological phenomena".

The age at which use of the drug began. according to practically all the studies reported, was in adolescence, though children have sometimes begun before puberty. In a group of American negro soldiers who had been admitted to hospital because of their cannabis-taking and its ill effects, 13% said they had started doing so before adolescence and two-thirds had started before they were seventeen.

The majority of users apart from university students. belonged to the urban proletariat. In Nigeria, where the habit has only recenty been developing on a large scale, the people mostly affected had drifted to the city and live on the fringe of organised society. Others who take it are long distance lorry drivers who believe that it increases staying power and courage, enabling them to take daredevil risks: among twenty-six cannabis-using patients admitted to Aro Hospital in Abeokuta, eight were lorry or taxi drivers. In North Africa. the rural population is also affected but much less so than the industrial workers and the unemployed who are often under-nourished. During Ramadan there is a rise in the number of cannabis-takers that has to be admitted to the mental hospital. Among cannabis users from Upper Egypt, who are predominently rural, there is a larger proportion of people with average or above average incomes than in those from Cairo. In several Asiatic countries the well-to-do smoke or otherwise consume their cannabis in private and in moderation; they do not get into the statistics or serve to tone down the published description of the coarse effects of cannabis.

In Morocco and Nigeria and some other African countries, cannabis-taking is not exclusively a masculine preserve, though women who do so are far fewer than men. In South Africa, 10,044 male Africans and 632 females were convicted of possessing cannabis; for Europeans, the corresponding figures were respectively 181 male and 4 female.

There is no convincing evidence that, other things being equal, the nationals of any particular country are more prone to take cannabis than, say, Englishmen or Burmese. In American reports, especially those based on military experience. Negroes and Puerto Ricans are to the fore but this is adequately accounted for in terms of the psychological, economic and civic background of their lives.

It is impossible at present to disentangle the psychological, climatic, social and religious factors which may determine the range and style of cannabis-taking. Confident statements about one or other such influence rest on impressions and conjecture. There are sweeping generalizations (such as that Moslems use cannabis because they are forbidden alcohol, whereas Hindus prefer opium) and detailed accounts of the extraordinarily diverse ways in which the drug is prepared and taken in different countries. Ethnic factors are loosely invoked. But never with adequate evidence. It has been asserted, for example, by a Psychiatrist who had had extensive experience in Algeria, that hashish is suited to the dreamy and contemplative temperament of the Moslem, alcohol to the hyperactice Westerner. Another authority, well acquainted with the Moroccan situation, says that the people of that country are imaginative and emotional and that they gain relief through the drug when they are in distress. A German psychiatrist who had spent two years in Morocco reported this year, that impulsive behaviour under hashish can be attributed to "the Moroccan mentality", which is also "prone to trance states". Another, with long Egyptian experience, attributes the growth of the practice there to foreign domination, the prohibition of alcohol, and the special tribunals for foreigners which made illicit traffic easy and safe. A Brazilian doctor maintains that dwellers in the lowlands need cannabis while those who live and work in the high plateaux of the Andes need the coca leaf to sustain them amid the extreme rigours of their lives.

Apart from the Brazilians and adherents of the Ras Tafari cult in Jamaica, a direct association with contemporary religions had not been reported; the continuing role of cannabis in Ayurvedic and Unani medicine cannot be regarded as of a religious nature.


General Attitudes

The attitude of the general public towards cannabis is not constant, nor evenly spread through the different sections of society. In India, and particularly in Bengal, taking the drug is not regarded with disapproval, according to most observers. Sixty or seventy years ago, however, most of the population looked down on the drug-takers, largely because of the degraded class they came from; but consumption of the drug by sadhus who were, in many cases, deeply committed to the habit, was viewed tolerantly. The public attitude in Mexico has also been reported to be tolerant. Satisfactory information about the attitude of various sections of Western society does not exist; inference from newspapers tends to be inconsistent.



Whether or how far particular features of personality conduce to the establishment of the cannabis habit is a highly contentious question, as much so as in the case of alcohol. At one extreme are those (like P. O. Wolff reporting on the peasants of Brazil) who deny that there is any predisposition, and at the other extreme those who regard defects of personality as prepotent - not only in bringing about habituation but also in determining the form of psychological disturbance produced. Since the estimates of personality are made in almost all cases retrospectively on persons known to be cannabis-users, there is much uncertainty as to whether the traits described were consequences of the habit or had preceded it and favoured its development. The temperamental qualities most often cited as predisposing are anxiety and impulsiveness, shyness combined with a longing for social contacts, immaturity and emotional instability, and various neurotic and psychopathic features. They are clearly unspecific.

Two American psychiatrists who studied a hospital group of cannabis-takers concluded that "the personality pattern of these men is one of strong libidinous desires resulting from early home conflict, a weak ego which identifies with an undesirable father image. and a super ego created by the moral mother.... Use Of marihuana removes the super ego which, in turn, strengthens the ego and enables it to satisfy the libidinous desires at various levels of infantile behaviour". Another writer, less psychoanalytically recondite, has found that homosexual tendencies are at work among the men who take cannabis to excess. A respectable body of opinion is to the effect that, though there is no doubt that faults of character may be found in those chronic users who reach hospital or prison, the majority of moderate users are within the normal range of personality. This is in sharp contrast to reports like that on the United States marihuana-smoking soldiers in the Panama Canal Zone, which found that 85% of the men were mentally abnormal - 62% were classified as constitutional psychopaths and 23 % as morons.



There are notoriously great differences between countries in the prevalence of cannabis use, but reliable estimates do not exist. Surmises are based on the quantities of the drug seized by the police, the number of convictions, and the proportion of people in mental hospitals who admit to having taken it. The figures thus arrived at are very high for some countries. Thus the most recent assessment for Egypt is that 27,000 kilograms of hashish were smuggled into the country, to be used by about 80,000 habitués (out of a total young male population of some three million persons). Gross figures are calculated for Morocco (50% of the population-"a million habitués"), and for some other countries. It is difficult to regard these as more than guesses.

The same uncertainty holds good of current estimates in North America and in Europe. A recent cautious statement, based on United Kingdom convictions for possessing or using cannabis, arrived at a figure of 30 regular users per 100,000 of population, and as many more who have tried it a few times.

Interest has centred on university students. In a sample of London students, 4% have been said to be steady users and 10% occasional users; because of penalties, fluctuations of opinion and other obstacles in the way of a trustworthy survey, such a finding cannot be generalized. It has been reasonably stated that the amount of addiction to a drug in any given population is a composite of availability, price, legal codes. suggestion, cultural attitudes, psychological needs and socio-economic factors; the product of such mixed influences could hardly be unchanging. In a questionnaire to which 1,245 students replied at Brooklyn College, New York, it emerged that progression to other drugs very seldom occurred though three-quarters of the students had, at one time or another, experimented with marihuana. One-third had done so on only one occasion.


Social Effects apart from Crime and Psychosis

Observers with long experience concur in the opinion that continued excessive use of cannabis over a period of years leads to moral and social decay; countries from, which such reports come are South Africa, Morocco, Algeria, Tunisia, Syria, Turkey, Astrakhan and India. In a few reports, such conclusions are extended to cover chronic use of the drug in only moderate doses but the majority of observers distinguish between heavy dosage and restrained use, restrained use is widely regarded as harmless in its effects, provided the consumer had, from the outset, a healthy mental constitution. In defining healthy mental constitution, circular reasoning is apt to creep in.

The Mayor of New York’s Committee on Marihuana found that people who had been smoking marihuana daily for years showed no abnormal psychological functioning which would differentiate them from non-users. The population selected for study, however, was composed mainly of men in prison who had volunteered for the study; they were hardly a representative sample of users and non-users. The Indian Hemp Commission of 1894 reported, after an elaborate enquiry, that moderate use produces no injurious effects except in persons with neurotic diathesis but that excessive use may intensify mental instability and moral weakness, and lead to loss of self respect.

The degradation that most writers report in the excessive chronic cannabis-user is apparent in several ways. He is irritable and impulsive, or inert and dreamy; he neglects himself grossly and is incapable of sustained effort; he may become a beggar or a vagrant, taking no responsibility for his family; he may practise homosexual or other sexual abnormalities or become impotent; he may be hypochondriacal or apathetic. His unkempt and prematurely aged appearance, inflamed eyes, tremor, and malnutrition are said to make up a fairly characteristic picture.


Effect on Occupational Capacity

Because of his impaired judgment, especially of space relations, and his irresponsibility, the chronic user - as well as the person acutely intoxicated - is dangerous when driving a car or lorry; this has been reported particularly from African countries. But the general occupational record of chronic users is not invariably bad, and no one has succeeded in determining how many continuous users become incapable of regular work. Bouquet and others have pointed out that there are some men who have been smoking hemp for thirty or more years and continue to follow their occupations satisfactorily: "A few daily pipes of kif are merely an agreeable weakness, enough to produce the condition of wellbeing they desire. They rest content with that". In contrast, a pronouncement in the United Nations Commission on Narcotic Drugs, E/CN/7/L.91, stated that "the study points up unequivocally the danger of cannabis from every point of view, whether physical, mental, social or criminological".

CrimePublished statements regarding the association between crime and cannabis illustrate the confused and contradictory standpoint taken up by experts, and the loose reasoning evident when a causal nexus is being considered.

Taking the views first of those who believe that cannabis can bring about criminal behaviour, some uncompromising conclusions are put forward, e.g. "literature surveys and personal contacts have clearly demonstrated the association between the use of marihuana and the commission of various crimes". Several describe outbursts by chronic users, in which they are wildly agitated and, seizing some handy weapon, attack a nearby person, often without the faintest motive for hostility: "murders are frequent and motiveless". A Greek investigator inquired into the subsequent history of 170 people who were arrested for possessing cannabis between 1919 and 1950 but had not previously been before a court for any offence; he found that 117 of these were subsequently sentenced for crimes of violence, blackmail and similar serious offences. P.O. Wolff wrote in 1949 that the drug had given rise to "a most appalling percentage of the tragedies and crimes in Cuban society", and he described similar consequences in Brazil. One of the outstanding French authorities on cannabis recounts the sequence of events he has often observed in victims of chronic intoxication: they pass into a state of torpor in some secluded spot; then abruptly they become agitated and the slightest opposition now moves them to violence and perhaps to sexual crimes (especially if they combine other drugs with their cannabis). A Moroccan investigator also emphasizes the lack of adequate motive or premeditation in the outburst of persistent, often murderous, violence; arson is fairly common; the impulsive attacks may be in several respects like those of an epileptic, occurring in a state of disturbed consciousness. Lesser crimes, such as theft and procuring, are common but do not seem to have evoked in observers the strong feeling indicated by such epithets as "heinous". "savage", which are applied to the outbursts of violence. Running amuck is considered by some to be a manifestation of chronic cannabism.

Opposite these supporters of the view that cannabis causes crime, are the almost equally numerous and authoritative writers who deny any direct causal connection though they do not dispute the frequent concomitance of cannabis and crime. The most influential and in some respects, the most thorough enquiries were made by the Indian Hemp Commission of 1894 and the Mayor of New York's Committee in 1944. The former concluded that "the connection between hemp drugs and ordinary crime is very slight indeed" but that excessive use does, in some very rare cases, make the consumer violent; six hundred witnesses were asked by the Commission whether they knew of cases of homicidal frenzy, and very few had. A considerable majority of the witnesses did not consider that the drugs produced unpremeditated crimes of violence and some said (as other Writers have since) that there is a negative relation because cannabis makes men quiet as a rule. The Mayor's Committee reported to a similar effect; many criminals might use the drug but it was not the determining factor in the commission of major crimes.

Eight observers in Brazil reported in 1962 that an exhaustive inquiry which they had made in the jails and hospitals had not produced any evidence that cannabis is an important cause of crime. This finding runs sharply counter to Pablo Wolff's observations in the same country.

Similar negative conclusions about the causation of crime in cannabis-takers come from Vancouver; the American Armed Forces abroad; New York and California and Nigeria. The Nigerian psychiatrist (Asuni), who examined a series of cannabis-takers, found no major crime among them except in one man who was schizophrenic, and another imprisoned for reckless driving. His general findings are in keeping with the moderate contemporary view, viz. that there is an antecedent predisposition towards psychopathic or criminal behaviour in those cannabis-user who do commit crimes, the cannabis often merely revealing or intensifying abnormal tendencies; and that circumstances arising from cannabis-taking may have fomented criminal conduct; "The people involved in cannabis-smoking . . . tend to be driven underground. In this situation their sense of isolation from the main body of society gets intensified. Their sense of value also changes to that of their new subculture, and this new sense of values may be generally asocial or anti-social". The Medical Director of the Lexington Narcotic Center in 1947 described the same downward progression: "It would be difficult for a normal personality to undergo such experiences without harm; for the type of personality that seems to be the background for addiction, they may cause irreversible distortions". Unfortunately, the type of personality that pre-disposes to cannabis-taking has not so far been described or identified convincingly.

Probable reasons why there should be fiat contradiction between the findings of different observers are: criminals in some countries base their defence on alleged cannabis intoxication which provoked behaviour that they cannot remember and for which they cannot be held fully responsible (just as epilepsy is often entered as the defence in our courts for crimes of violence); many who use cannabis in various countries combine it with opium, heroin, amphetamine, barbiturate or alcohol, and it is impossible to tell which, if any, of these is to blame for the criminal behaviour observed in a given individual; the samples of persons investigated have mostly been small and the history of drug-taking, its duration and degree in each individual has been provided by the man himself, who often believes it to be to his interest to lie about it. When criminal behaviour occurs in people who take cannabis steadily, it is by some confidently assumed, and by others confidently denied, that the crime was caused by the cannabis, though thc available data are insufficient to permit a judgment either way. Only rarely in published reports on criminals and cannabis has a satisfactory effort been made to distinguish between chronic cannabis-use and infrequent or casual experimentation, or between criminals who have recognizable mental disorders and those who are mentally normal, apart from the criminal episode.

The one delinquency which receives general reprobation is driving while under the influence of cannabis whether on an isolated occasion or when bemused by chronic excess. The old story that cannabis was taken to nerve men to go into battle and to commit murders to order, has little or no foundation except perhaps that the mercenaries employed to put down riots and revolts in lndia were, according to the Indian Hemp Commission, habitual consumers of cannabis who acquired "Dutch courage" thereby. As mentioned earlier, advantage may be taken of the heightened suggestibility of the cannabis-user.

The most likely relation that emerges from the welter of connecting statements is that chronic or excessive indulgence in cannabis may, in some people - a small minority of’the male public at risk - lead to attacks of disturbed consciousness, excitement, agitation, or panic, and reduce self control. The extent to which the affected person may commit a crime in this state of mind depends more on his personality than on the dose or preparation of cannabis which he has been taking.



"Cannabis psychoses" have been frequently described and the accounts include practically every known variety of mental disorder. The predominant and most frequently put forward are schizophrenia and especially catatonia; paranoid states; manic excitement; depression and anxiety; and dementia. A writer on the subject whose report (1903) has been often quoted or borrowed, was Warnock, the Medical Superintendent of the mental hospital in Cairo. He had recognized as hashish psychoses an acute hallucinosis with restlessness and incoherence, and a manic condition; but he added that "besides these types, there are numbers of cases of chronic mania, mania of persecution and chronic dementia, alleged to be produced by hasheesh, but I have no means of verifying these allegations". He also wrote: "I doubt very much if hasheesh insanity can be at present diagnosed by its clinical characters alone". This is a cautious view; other observers who have seen many patients to whom they gave this diagnosis, dwell on dementia as a fairly common outcome of chronic use of the drug, or assert that there is a typical and striking uniformity of symptoms in the cannabis psychosis. An Indian psychiatrist. Dhunjibhoy, defines it: "A patient admitted to an Indian mental hospital with intense excitement, grandiose ideas, tendency to wilful violence, a peculiar eye condition (marked conjunctival congestion), total amnesia of all events, attacks of short duration, followed by complete recovery, with a history of the drug habit and without a psychopathic or neuropathic heredity, is a typical case of "hemp insanity." Some obsersers describe severe mental deterioration as a familiar outcome while others with much experience say this does not occur at all.

The term "Cannabis psychoses" begs the question of the existence of such a syndrome. On the one hand, there is a cloud of witnesses qualified to speak by lifelong contact with the problem in mental hospitals of countries in which cannabism is very common: they are convinced that the condition is correctly identified. "The effects of the drug are detailed in all the well known text-books and that its abuse is a direct source of serious mental disorder is indisputable", wrote a senior doctor of the I.M.S. in 1923. A high proportion of the patients admitted to mental hospitals in India and Egypt and elsewhere were diagnosed as falling in this category.

On the other hand. there were equally informed doubts as to the legitimacy of the diagnosis in many cases. These doubts were cogently expressed by the Indian Hemp Commission in 1894. Out of 1,344 admissions to the asylums of India during 1892, there were only 98 patients in whom the use of hemp drugs could reasonably be regarded as a factor in causing the insanity, and in 37 of these there was a clear history of some other cause which might have co-operated with the hemp drugs. The Commissioners concluded, after an enquiry of still unequalled scope, that "the usual mode of differentiating between hemp drug insanity and ordinary mania was in the highest degree uncertain and therefore fallacious.... The excessive use of hemp drugs may, especially in cases where there is any weakness or hereditary predisposition, induce insanity. It has been shown that the effect of hemp drugs in this respect has hitherto been greatly exaggerated, but that they do sometimes produce insanity seems beyond question". Nevertheless, it bas been questioned. Even so guarded a statement implies that there are some sure criteria for establishing the causal role of the cannabis, either when it has been established that a man exhibiting a so-called "functional psychosis" had previously been for years smoking or eating cannabis: or when such a history precedes the onset of an "exogenous psychosis" exhibiting the cognitive and other defects attributable to physical or chemical damage to the brain. As a rule the writers on the subject do not give enough detail to warrant any attempt at retrospective diagnosis; but in those who do, there are instances of persistent confusional syndromes shading off with the passage of time into chronic dementia, in which the cannabis seems to have been the major cause.

The reasons for the discrepancy in opinion expressed by equally experienced observers seem to be:

(1) The motion of a single cause for mental disorder, widely held in the last century, is no longer regarded as tenable. Consequently the last two decades have seen few assertions about cannabis being the cause of insanity, but many espousing the view that it has been either a necessary or a contributory cause, especially where evidence of predisposition to psychosis is forthcoming from a patient’s previous personality and health record.

(2) The clinical picture of what has been regarded as cannabis psychosis has not had any characteristic features (such as delirium tremens has. for example). It has often been indistinguishable from schizophrenia.

(3) The reasons put forward earlier (page 48) for the discrepant opinion about crime and hashish, apply here.

(4) In many of the published reports it is made clear that the hashish was combined with other substances - datura, alcohol, heroin or amphetamine - which could be responsible for the psychosis which developed. The cannabis might have had nothing to do with it.

(5) The history of the patient’s previous mental state has been only cursorily enquired into, often for lack of dependable informants. Many of these patients may have had established or incipient mental illness; quite independently of cannabis, before the incident - a crime or a catastrophe - which brought them into a mental hospital.

(6) The diagnostic methods employed in many studies were, by any reasonable standard, woefully inadequate. In one large area, the diagnoses might be made by a policeman. The long-standing belief that cannabis causes insanity could strengthen this diagnosis in a doubtful case. Ingrained beliefs and habits are known to be powerful enemies of unbiased diagnosis.

There is no unequivocal evidence that cannabis can be the major or sufficient cause of any form of psychosis. Neither is there clear evidence that moderate euphoriant or tranquillizing doses, even if taken over a long period, do mental harm in the majority of people of average mental stability, though rare isolated cases are on record in which persons apparently in good mental health have reacted with a pronounced mental disturbance to moderate doses. In large doses, cannabis can result in severe psychosis which may not clear up; it can be of the schizophrenic paranoid form, anxiety, or excitement. It is usually assumed that persons constitutionally predisposed to psychosis will be those most vulnerable to cannabis; but although this is in keeping with current psychiatric theory, it lacks experimental or statistical confirmation. In many cases it could be argued that the patient would have fallen ill with schizophrenia or other psychosis even if he had not had any cannabis. This would be a weak contention if it were not so often stated by clinicians that the "hashish psychosis" may be indistinguishable from schizophrenia.



Benefits have been claimed from cannabis, but trustworthy reports have been few and vague. It is said to promote relaxation and calm after the trials of daily life, and to assist shy people to enter into warm social relations; it lessens awareness of pain and misery; it helps to allay neurotic anxiety; and it is an aid to religious fervour. A prominent American psychiatrist recently wrote, apropos of eleven university students who had had severe adverse reactions from cannabis:

"The evaluation of harm a drug does requires some consideration of its benefits. Users of marihuana state that it is a source of positive pleasure, that it enhances creativity, that it provides insight, and that it enriches their lives. These are hardly minor claims. All but two of the eleven individuals reporting adverse reactions considered the benefits to far outweigh the unfortunate aspects and they planned to continue use of the drug".

From ancient times, cannabis has been credited with therapeutic powers, especially in India. Its introduction into Europe in the mid-nineteenth century led to the familiar burst of enthusiasm for a new remedy. This dwindled as time passed but died slowly: "During the period 1840 to 1900, there were something over one hundred articles published which recommended cannabis for one disorder or another". Its vogue preceded the advent or synthetic hypnotics and analgesics, and it was lauded for its effect in alleviating pain, migraine, insomnia, dysmenorrhea, difficult parturition and cramps. In 1890. Russell Reynolds wrote that "when pure and administered carefully it is one of the most valuable medicines we possess".

It was also said to be good for mental disturbances though its proponents rather shamefacedly acknowledged that this line of treatment had a homeopathic flavour. As late as 1928, an article appeared reporting that cannabis was valuable for severe melancholia. There are still a few who assert the therapeutic value of the drug: because it heightens suggestibility and weakens inhibitions, they find it a useful adjuvant in eliciting submerged memories and feelings which the patient cannot otherwise communicate. Its antibiotic powers have also been explored in Central Europe.



Even on such straight-forward matters as tolerance and the development of physiological dependence, there are contradictory statements. Practically all informed opinion is satisfied that neither of these develops; yet there are statements to the contrary. "Quite serious disorders are observed in those addicted to the drug over a long period when their poison is removed. Attacks of physical prostration and intellectual apathy, especially, are noted". (Bouquet). A Turkish and an Egyptian observer separately describe how the patients increase the quantity of cannabis they take in order to maximize the pleasurable effects. In Russia, Skliar has observed severe symptoms after withdrawal of "anascha": among them were anxiety, pains in the limbs, vomiting, diarrhoea. Sweating, yawning and depression, all of which would clear up quickly if some of the drug was administered. (There seems. however, doubt as to whether opium and cocaine may have been mixed with the cannabis in "anascha".) Frazer in 1949 observed states of extreme violence and confusion developing in Indian soldiers whose supply of cannabis had been abruptly stopped. To round off the picture with a paradox, Meunier and Richet found that the human organism becomes more sensitive to hashish the more it is taken, with the result that the dose could be gradually lessened to half without diminishing the effects.

Although it is said that many of those who take to cannabis prefer it because they know they can stop it without any disagreeable withdrawal symptoms, several observers agree that the psychological symptoms which develop on withdrawal can be very disagreeable, the main ones being loss of appetite, dyspepsia, pain in the abdomen, fatigue, insomnia, agitation, palpitations and headache.



In some countries, notably India and North Africa, it was not uncommon for cannabis to be combined with datura or with opium, alcohol or heroin. Immigrants into Israel from North Africa, the Near East or the Middle East were "prone to take any narcotic drug they could lay their hands on".

Progression from cannabis to heroin, morphia or cocaine is the subject of discordant conclusions, often based on concordant data. From many countries, including the United States, come reports that a very high proportion of all heroin addicts have previously taken cannabis and that once they have progressed to this stage, they seldom return to cannabis. What determines the progression is contested. The majority of observers attribute it to association with friends or acquaintances who have themselves become heroin or cocaine addicts; others suppose that it arises from dissatisfaction with the relief or pleasure to be obtained from cannabis; and a minority postulate a predisposition to marihuana which is also a predisposition to heroin. No one suggests that there is a truly pharmacological reason why such "escalation" should occur. Some hold that in a large proportion of cannabis-users, especially adolescents, there is Some obscure but powerful factor (which could be psychological or social) greatly increasing the risk that they will take to opiates sooner or later; other authorities maintain that the transition from the marihuana stage to the heroin stage occurs only in a small minority of marihuana-users and that there is no more justification for indicting marihuana as a preliminary to dependence on narcotics than for indicting coffee or tobacco.

Into this darkness some light is cast by a recent study of 2,213 addicts admitted to Lexington and Fort Worth hospitals during 1965. The patients were classified according to the state they came from, the opiate they had been taking and whether they had been marihuana-users or not In each of sixteen states, more than 50% of the subjects had used marihuana as well as opiates. In each of twelve other states, most of the opiate addicts had never used marihuana. The dominant sequence of events had been marihuana-smoking, arrest, and then opiate use; the respective mean ages for these three events were, first, marihuana-use at 17, arrest at 19, and then onset of heroin use at 20. When the marihuana-users were compared with the non-users of this drug, it was found that the former were twice as likely to be heroin addicts and to secure their drugs from underworld pushers as the addicts who said they had never used marihuana. They also had an earlier age of arrest and of onset of opiate use. Ball and his colleagues who made this study conclude: "As to the issue of association, marihuana-smoking is seen as a predisposing influence in the aetiology of opiate addiction in the United States. Among metropolitan residents of the high addiction Eastern and Western states, opiate use is commonly preceeded by the smoking of marihuana cigarettes and arrest. Thus, both marihuana-use and delinquency are predisposing factors within the metropolitan host environment … Enough is now known about the association of marihuana and opiate use to delineate the dominant relationship of these two events. The incipient addict is predisposed to opiate addiction by his use of marihuana, for the following reasons: marihuana is taken for its euphoric effects, it produces a "high’‘; both marihuana and heroin are only available from underworld sources of supply; both are initially taken within a peer group recreational setting; both are illegal; the neighbourhood friends with whom marihuana-use begins are often the same friends who initiate the incipient addict to the use of opiates. . Data of the present study support the conclusion that marihuana-use is closely associated with opiate addiction in the high drug use metropolitan areas of the East and West, but not associated with opiate addiction in twelve Southern states".

This detailed and temperate study lends support to the view that marihuana-users are more likely than non-users to progress to opiate addiction.



In many countries laws have been passed which make possession and use of cannabis an offence; in some, the penalties are very severe, and may include capital punishment for trafficking in the drug. The extent to which the laws are enforced varies greatly. Penalties and sentences are often equated with those considered appropriate for heroin and morphine addicts: the Medical Director of the Federal Bureau of Prisons in Washington, D.C. said in 1962: ‘’In our Federal prisons we have about 160 marihuana offenders; the average sentence of the group is nearly six years, which is approximately what the average sentence for (all) drug offenders is".

There are diverse opinions about the effectiveness of penal legislation. A few believe that it has a deterrent effect; thus a Greek observer is sure that if the sale of hashish were legal in his country, the power of advertising is so great that very large numbers of people would take to the drug. Others review the fluctuations of state policy in their own country, veering from rigorous application of severe laws to lax administration and tolerance, and conclude that the laws have not achieved their purpose. It seems, reading the contrasting statements on this matter, that most persons with relevant experience would like to have legislation applicable to the excessive user and the trafficker, but they object to blanket legislation which permits and even encourages, the imposition of long terms of imprisonment or other stringent punitive measures. It is generally acknowledged that it is not so much the law as the way it is acted on by the police, customs officers and magistrates that determines its efficacy (which is, in any case. limited). Lindesmith, advocating that legislation should be on the same lines as for alcoholism, gives an example‚: that persons driving a car while under the influence of marihuana might be fined and deprived of their licences for a period of time:

‘‘Laws such as this, with penalties of a reasonable nature would probably be more effective than those now in effect because they would be more enforceable and more in accord with the nature of the problem being dealt with. They would have the effect of reducing the discrepancy that now exists between the laws as written and the laws as they are actually enforced".

Total prohibition of all indulgence in cannabis was firmly rejected by the Indian Hemp Commission in 1894: "The Commission now unhesitatingly give their verdict against such a violent measure as total prohibition in respect of any of the hemp drugs". Their chief reasons were that cannabis is, in moderation, harmless; that its withdrawal would excite much resentment among the population, especially the poorest sections; and that if it were forbidden, the people would take to more dangerous drugs. But they went on to say: "While opposed to this amount of interference, the Commission feels strongly that a regulating influence is necessary and should, in future, be exercised by the Government of India over the various systems of administration of the excise on hemp drugs’ .

The fear that the prohibition of hashish would result in recourse to worse drugs such as heroin, datura or alcohol, has been expressed by several workers, especially those with Tunisian experience. An outstanding authority (Bouquet) wrote in 1951 that if cannabis had been absolutely prohibited thirty or thirty-five years ago in North Africa, the problem would now be manageable but the point has been reached at which suppression would result in an increase in heroin addiction. There is, however, some inconsistency in this matter. Writers who fear that total prohibition would lead to worse dependence on other drugs, at the same time advocate determined police action to cut off all clandestine supplies of cannabis - a measure which would surely have the same effect, if successful, as total prohibition. A variant of this fear is voiced by the W.H.O. Expert Committee on Mental Health (1967) who say that "condemnation by society may arouse guilt feelings in the user, drive him to even greater dependence on drugs and prevent him from seeking treatment".

Another observer, chiefly concerned with comparing United States with English methods of dealing with narcotic addiction, emphasized in 1962 that in America people were driven by social. legal and economic pressures to band together to establish their own group way of life, or subculture: "Addiction as such may not be as antisocial as the kinds of behaviour forced on the addict by the punitive approach to addiction". The more cannabis-taking is driven underground, or the more it is punished by imprisonment, the greater, according to some writers, is the likelihood of cannabis-smokers being corrupted and turned permanently towards antisocial behaviour of other kinds.

Partial prohibition or indirect measures of control have been tried in many countries. The commonest methods are by taxation and setting up a government monopoly. Neither, from the statements of those who have had experience of the effects, has proved effective in limiting the spread or reducing the prevalence of the habit. A few observers have urged that the risks can be reduced by suppressing the resin or other concentrated form while tolerating the powder; or by harrying and supervising adolescent marihuana-users, on the assumption that if they could consume as much as they wished whenever they wished there would be a much larger number of serious chronic victims - "wretched ragamuffins who are a danger and a burden to society". But these assumptions and assurances are made on the strength of the particular writer’s experience; they lack statistical or other firm support.

It is generally agreed that taxing the drug does not deter the inquisitive or venturesome experimenter, the adolescent who emulates his slightly older associates, or the psychologically dependent man who craves the drug. They find the money somehow to pay for it, as people do for alcohol.

Control by blocking the sources of illicit supply is evidently the ideal.’The measures taken have been described in official reports. They bypass the small fry - the pedlars and carriers - and aim at catching the wholesale trafficker; they also try to destroy the hemp crops: thus the United States Bureau of Customs and the corresponding Mexican authorities collaborate in detecting the hemp fields and rooting them out. A minority of those who discuss prohibition and its problems are concerned with what moral justification the state has for interfering with a citizen’s right to do as he pleases as long as he does not infringe the rights of others or harm society. Some stress the alleged detriment caused by cannabis to the user’s character and his occupational capacity, reducing his social usefulness; or they point to injuries caused by his behaviour in driving lorries or cars under the influence of the drug. On the other hand, some urge that if alcohol and tobacco can be tolerated and taxed, there is no logical ground for abstaining from doing likewise with cannabis (onto which, they suggest, an unwarranted moralistic stigma has been pinned); they believe that if a drug, such as alcohol or cannabis, is generally and readily obtainable in a given society, most people learn to use it in moderation, while the psychopathic minority who use it to excess would do so with some available alternative drug anyway. The significant debacle of alcohol prohibition in the United States has a bearing on the argument for treating cannabis like alcohol. A well established, socially permissible drug is evidently ineradicable by total prohibition whereas a comparative newcomer like cannabis in Western countries, is a weakling which might be kept in check by firm action, some suppose.

At the present time, it is widely accepted that dependence on a drug is a medical condition calling for medical treatment. This contention is easily justified in the case of drugs to which a physical dependence may develop. In the case of cannabis, however, where the dependence is purely psychological, the issue has been contested. The majority of writers are in favour of psychiatric treatment (provided that the user wants to be treated), combined with social measures of rehabilitation and appropriate social investigation. Broadly. of course, a medical approach is concerned with the welfare of the individual. a social approach is directed more at the protection of society: they complement each other. An antithesis between medical research and social research in this field or between medical and social treatment is forced.

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