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II CANNABIS AND ITS CLINICAL FEATURES
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.
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.
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.
the following paragraphs we try to portray, so far as possible in laymans
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.
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.
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.
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.
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.
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.
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.
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 Mayors Committee on Marihuana
(1944), that the long-term consumption of cannabis in moderate doses has no harmful
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.
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.
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.