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SECTION II CANNABIS AND ITS CLINICAL FEATURES

19. Cannabis is the generic name of Indian hemp (C.Sativa). Cannabis drugs are obtained from the unfertilized flowering tops and the leaves of the plant, which can be grown in climates varying from temperate to tropical. Cannabis Sativa is one species which may be divided into two groups: (i) C.lndica, which is grown in the Indian sub-continent or from seeds originating there, and (ii) C.non-lndica. which originates and is grown elsewhere. The potency does not differ as between these groups, provided that the conditions in which they are grown are the same. To yield a potent drug a high temperature and low humidity are necessary, and these conditions are seldom available naturally in the United Kingdom.

20. There are many local names for preparations of cannabis, e.g. the dried leaves may be termed marihuana, or dagga; the resin obtained from the flowering tops is usually called hashish, or charras. The Anglo-Saxon countries also have an extensive and continually changing vocabulary.

21. Cannabis contains a number of identifiable constituents. Recent research indicates that the tetrahydrocannabinols (THC) are active principles: some have been shown to be highly potent. A detailed description of the pharmacology of cannabis is given in Appendix 5.

Clinical Features

22. In the following paragraphs we try to portray, so far as possible in layman’s language, the effects of cannabis smoking (a) in moderation (b) in excessive use on a particular occasion, leading to acute intoxication. and c. in chronic use. This digest reflects the experience of a number of different cultures. In Section III we try to relate United Kingdom experience to this picture.

23. The effects of drugs which act upon the central nervous system are not determined solely by the drug and its dose. They are dependent also upon the person taking it, upon the immediate setting in which it is taken, and upon the cultural background. These are liable, in certain persons and in certain conditions, to produce unexpected effects. Any account of the effects or a drug can only be fully appreciated if this possibility is borne in mind. Some people can even take opiates regularly and become physically dependent on them without obvious deterioration in their health or social efficiency.

24. The response to cannabis may vary according to the form in which it is taken and to the dose consumed. Where it is smoked, the effect normally comes on within half an hour and lasts for two or three hours. When it is taken by mouth the onset is delayed sometimes up to two or three hours, and the effect may last twice as long. Because of the relatively rapid onset when the drug is smoked, experienced smokers can adjust their dosage to achieve the effect that they seek. When the drug is taken by mouth this adjustment is less easy to achieve. Apart from these considerations there does not appear to be any significant difference in effect between the many different forms of cannabis that are used throughout the world.

25. The taking of cannabis does not normally result in any characteristic physical effects except that of redness of the eyes. When the drug is smoked there may be some initial rawness and burning in the throat, and tightness in the chest. Upon occasions, particularly when the subject is initially anxious, headache may result. There may be nausea and vomiting. Once the effect of the drug has worn off there may be an increase in appetite, even ravenous hunger. There have been isolated reports in which death has been attributed to cannabis, but these are very rare and their validity cannot be confirmed.

26. The effects of cannabis in moderate amounts are predominantly psychological. They begin with a sense of excitement or tension, sometimes with apprehension or hilarity, followed as a rule by a sense of heightened awareness: colours, sounds and social intercourse appear more intense and meaningful. A sense of well-being is then usual. After this a phase of tranquillity and of passive enjoyment of the environment normally follows until, after a few hours, fatigue sets in and the subject sleeps. Although a "hangover" may follow this is not a common occurrence.

27. When the amount consumed is more considerable, or the subject is of a nervous disposition, or in an uncongenial social setting, symptoms of anxiety may be the first effects. These may be expected to settle. and the subject enters the euphoric or the passive state described above. On occasions, however, the anxiety may mount and symptoms suggestive of a deluded state ensue. As a rule these effects are not overwhelmingly intense. In most cases the subject retains his sense of contact with reality and remains aware of the fact that he is under the influence of a drug whose effects will pass off. On rarer occasions, usually with a heavy oral administration. the disturbance may be more profound.

28. The untoward effects of over dosage as described above appear, in the great majority of cases, to pass off uneventfully as the drug clears from the system. They would be described in medical language as a toxic psychosis. There have been reports of a psychotic state persisth1g longer, even in rare cases giving place to what appears to be a prolonged schizophrenic illness, but it is difficult from these reports to assess the exact role of the cannabis in these circumstances.

29. Having reviewed all the material available to us we find ourselves in agreement with the conclusion reached by the Indian Hemp Drugs Commission appointed by the Government of India (1891-1894) and the New York Mayor’s Committee on Marihuana (1944), that the long-term consumption of cannabis in moderate doses has no harmful effects.

30. There have been reports, particularly from experienced observers in the Middle and Far East, which suggest that very heavy long-term consumption may produce a syndrome of increasing mental and physical deterioration to the point where the subject is tremulous, ailing and socially incompetent. This syndrome may be punctuated on occasions with outbursts of violent behaviour. It is fair to say, however. that no reliable observations of such a syndrome have been made in the Western World. and that from the Eastern reports available to us it is not possible to form a judgment on whether such behaviour is directly attributable to cannabis-taking.

31. In Western society cannabis is sometimes taken with other drugs. There is no evidence to suggest that cannabis in man in customary doses enhances the effect of other drugs. When combined with another drug. cannabis in man does not cause this to exert an effect quantitatively greater than that which would result from the use of that drug alone in the same dosage; when cannabis is used with other drugs such as L.S.D., or occasionally alcohol, it is their effects, rather than those of cannabis, which predominate. Some persons who have taken L.S.D. frequently are apt to get a recrudescence of the hallucinogenic experience as a consequence sometimes of quite small doses of cannabis.

32. Those who believe that there is a syndrome of chronic excessive cannabis-taking describe symptoms of physical deterioration such as yellowing of the skin, tremor, wasting and unsteadiness of gait. Here again it is very difficult to make a confident judgment as to the role played by the drug and the changes brought about by other factors such as malnutrition. There is no evidence that in Western society serious physical dangers are directly associated with the smoking of cannabis.