The Cannabis Habit

Sections

Varieties, preparations and active principles of Cannabis sativa
Short - term psycological effects
Addiction
Long-term psychological effects
Cannabis psychosis
Personality traits of Cannabis users
Other effects
Conclusions
Summary

Details

Author: H.B.M MURPHY, M.D.
Pages: 15 to 24
Creation Date: 1963/01/01

The Cannabis Habit

A review of recent psychiatric literature

Ph. D. H.B.M MURPHY, M.D.
Associate Professor, Department of Psychiatry, McGill University, Montreal.

During a recent visit to the island of Jamaica to plan some socio-psychiatric research, it was pointed out to me that medical men there were in need of guidance and possibly research on the question of Cannabis habituation. Neither local psychiatrists nor general practitioners were clear regarding which disorders should be attributed to the drug, and it was hoped that I could provide some answers. As the following review shows, however, the Jamaicans are by no means alone in the confusion which they feel on the subject, and further research seems called for.

The present notes cover the majority of scientific papers published on Cannabis over the past twenty-five years and referring to the psychiatric sequelae to its use. I have chosen to ignore most of the literature dealing with purely botanical, biochemical and physiological aspects of the subject, as also most papers from a psychiatric or pseudo-psychiatric viewpoint which did not appear to be based on original observations.

Varieties, preparations and active principles of Cannabis sativa

Cannabis sativa L., Cannabis indica and Cannabis americana are agreed to be the same plant, varying somewhat in size and appearance with climate and soil, but always producing an intoxicating principle [ (2)] , [ (34)] . It is consumed in many ways and under many names in different parts of the world - hashish, kif (N. Africa); ganja, charas, bhang (India), ma jen (China), dagga (S. Africa); marihuana or mariajuana, reefers, tea (N. America); maconha (S. America). Conditions of cultivation probably influence the strength of the active principle [ (13)] , [ (57)] , but less so than the conditions of collection and preparation. The main psychopharmacological agent, tetrahydrocannabinol, has been reliably identified [ (2)] , [ (14)] , [ (25)] , and appears to be produced mainly or exclusively by the unpollinated female flowers. Preparations from the leaves of the plant contain little or none of this agent, whereas those from the pure resin excreted by the flowers at a certain period contain it most strongly [ (2)] , [ (8)] . Ganja, marihuana and most other commonly used preparations usually consist of the chopped, dried flowers and tops, but there is considerable variation in the manner of preparation. Smoking with deep inhalation appears to produce more rapid and more predictable results than ingestion [ (3)] , [ (12)] , but the latter is also used, and a snuff is sometimes found.

A synthetic analogue (synhexyl) was at one time used for the treatment of depression [ (2)] , [ (35)] , but proved less satisfactory than later antidepressants.

The drug can be fractionated and identified by paper chromatography, which should contribute to a more rapid understanding of its elements, but there is as yet no satisfactory test for its detection within the body [ (14)] , [ (29)] .

Short - term psycological effects

Summary of reactions of 100 subjects accustomed to Cannabis smoking, after administration of ? g. to 2 g. of ganja or charas through a pipe

TABLE I

Effects

Number

1. Euphoria and feeling of exhilaration
74
2. Depression
12
3. Increased energy, desire and capacity for work
39
4. More talkative
60
5. Mental activity and efficiency increased
30
6. Mental activity and efficiency decreased
10
7. Sharpening of appetite
58
8. Diminution of appetite
30
9. Appetite not affected
12
10. Feeling of constriction in the throat
40
11. Reaction to work as regards fatigue:
 
( a) Less fatigue
60
( b) Sense of fatigue enhanced
20
( c) No effect
20

Many reports exist of cannabis being given to volunteer subjects - both naive and experienced in its use - and there is considerable unanimity regarding the initial effects. These are: ( a) a dulling of attention; ( b) loquacious euphoria of variable duration; ( c) usually some psychomotor activity and affective lability coloured by the underlying personality; ( d) perhaps some distortion of perception and time sense, depending on the dose; ( e) perhaps some lassitude culminating in deep sleep if the dose is sufficient [ (2)] , [ (3)] , [ (8)] , [ (9)] , [ (12)] , [ (46)] , [ (51)] . In South Africa, the staff of the Pretoria mental hospital distinguished three categories of reaction:- cases showing dullness and fatuous euphoria only; cases showing additional irritability and mild excitement, culminating in sleep; and cases showing additional confusion [ (31)] . A summary of the reaction of 100 regularusers to a single dose, as reported by the Chopras from India, is given in the accompanying table. Other effects, produced in some subjects only, are an oeiric ecstasy (8, 10, 36); an acute sensitivity to sights and sounds, especially any slight noise (8, 9); hallucinations and delusions; anxiety [ (9)] ; and depression. Most observers agree that the experienced user can be distinguished from the novice by his knowledge of the correct dose required to produce the euphoria (or oneiric ecstasy, if that is the aim) without any of the more disturbing effects, and it is also found that most habitual users regulate their intake in this way [ (3)] , [ (31)] , [ (51)] .

Intellectually, the drug appears to be able ro release repressed ideas, but at the same time reduces work drive so that the ideas are rarely followed through or put into action. Thus, Rorschach tests carried out under the drug showed greater originality and elaboration in the responses, with greater variety, but at the same time the number of responses was reduced (51). Mechanical tests under the drug resulted in greater speed, but at the same time loss of accuracy [ (51)] . A naive subject of Adams, when under the drug, more than held his own at poker against expert players, thus showing that mental acuity was not reduced when attention was held, but painter and musician subjects of Williams, left to themselves, failed to carry out the creative programme they had mapped for that time. Performance in I.Q. tests appears to be either slightly reduced [ (51)] or unchanged [ (46)] .

Aggressiveness or antisocial behaviour is agreed to be less common with Cannabis than with alcohol (3, 12, 20, 46), but there are three main types of situation in which it can arise. The first is when a naive subject develops a panic state in response to the hallucinatory experiences which the drug induces, and in his panic attacks any object in sight [ (9)] . The second is during the phase of hypersensitivity and psychomotor activity, when the subject's reactions to unpleasant external stimuli may be more emphatic than is customary [ (3)] . The third is when the drug is taken, as alcohol might be, to release repressed feelings of hostility. Bouquet has stated that the drug is still sometimes used in North Africa by criminals seeking confidence before a sortie [ (8)] - the use among the original Assassins - and Charen notes that relief from inferiority feelings can lead to bullying, swashbuckling behaviour. He states that although his Negro soldier habitues were delinquent without the drug, they were more so when under its influence [ (11)] . However, there is no doubt that such uses, or such events, are exceptional. Most serious observers agree that Cannabis does not, per se, induce aggressive or criminal activities, and that the reduction of work drive leads to a negative correlation with criminality rather than a positive one [ (3)] [ (9)] , [ (12)] , [ (41)] , [ 46] .

In the papers reviewed, the only instances where cannabis is alleged to have led to homicide or mayhem in such a fashion refer to North Africa and are not well documented [ (7)] , [ (8)] ; but the suggested effects are plausible and hence should be kept in mind for their medico-legal significance.

A further, qualifying point that must be kept in mind is that the results of taking cannabis are considerably influenced by the individual's expectations or by the social or cultural setting. In the North American Negro subjects of Charen and of Marcovitz some sexual stimulation and release of repression was expected and much sexual activity resulted, although most investigators are agreed that cannabis has no aphrodisiac effect. In Indian Brahmins and some N. African groups a form of oneiric ecstasy is quite regularly obtained [ 7] , [ (10)] , [ (12)] , whereas in South African and North American subjects it is rarely mentioned [ (11)] , [ (20)] , [ (28)] , [ (31)] , [ 46] . The hallucinations and disturbances of time sense sought and reported by the "Club des Haschichins" of Baudelaire and Gautier are avoided by most users elsewhere.

Addiction

There is at the present time a recognized discrepancy between the medical and the legal definition of addiction, and the discrepancy is nowhere more confusing than in the case of Cannabis. In 1955 the WHO Expert Committee on Addiction-producing Drugs stated that "Cannabis itself comes definitely under the terms of its definition of addiction" (15 a). Two years later, however, they found it necessary to emphazise the difference between addiction and habituation, and when such a distinction is made the question arises whether Cannabis ought to come under the heading of habit-forming rather than addiction-producing. Since the distinction between habituation and addiction was an attempt at increased scientific precision rather than a legal dictum, however, the declaration against Cannabis has never been changed, and the question has not been publicly discussed by the Committee.

The cannabis habit 17

Addiction, according to the 1957 Expert Committee, is characterized by:

"(1) an overpowering desire or need (compulsion) to continue taking the drug and to obtain it by any means;

"(2) A tendency to increase the dose;

"(3) A psychic (psychological) and generally a physical dependence on the effects of the drug; and

" [ (4)] A detrimental effect on the individual and on society. [ 15]

Habituation, according to the same report, is distinguished by absence of true compulsion, absence of physical dependence, little tendency to increase the dose, and by use of the drug only for the pleasurable sensations it induces, not for relief of feelings of lack. The obvious illustration of a habit-producing drug is alcohol.

The majority of papers here reviewed hold fairly clearly that, in terms of the above definitions, Cannabis is "habit-forming" rather then "addiction-producing ". Most individual users intensively studied could accept or abandon the habit without withdrawal symptoms; none of them showed true physical dependence; none of them had shown a real tendency to increase dosage and most, when given as much as they asked for, tended to be quite moderate in their demands or to reduce dosage.

In North America, the main recent data supporting a belief in an addition-producing effect relate to two groups [ (11)] , [ (28)] of mainly Negro soldiers who either demanded to be given the drug or sought army discharge on the grounds that they were useless without it. One has a strong impression, on reading the two papers, that these subjects were playing strongly on the nuisance value of their alleged addiction, and Charen notes that "when talked to in a kindly, sympathetic manner, feelings of anxiety which they attributed to the drug deprivation disappeared in the course of the interview because they were able to represent themselves as adequate individuals in terms of their own standards" [ (11)] . This is not the reaction one would expect from true addicts, and the over-all picture might be interpreted rather as attachment to what we now call a delinquent subculture- one in which marihuana smoking plays a limited but significant role - than as a dependency on the drug itself. Nevertheless, the general failure of the Marcovitz or of the Charen team to wean the subjects away from their demands for the drug does suggest an addiction to something, even if it be only a way of life which the marihuana supports, and even if the subjects were poor material in the first place.

All other main investigators within the United States deny an addiction-producing effect. Allentuck et al state that "the psychic habituation to marihuana is not as strong as to tobacco or alcohol" (3). Freedman & Rockmore, studying a much larger sample of army habitues than the Charen or Marcovitz teams, could find no evidence of deteriorating effect on mind or on body, and noted that most of the users had gone without the drug for long periods without reduction in efficiency or need for medical help [ (20)] . Two official army pre-war investigations, published a little more than twenty-five years ago but deserving mention since they .appear to have been overlooked by other reviewers, concluded that "there is no evidence that marihuana as grown here [Panama Canal Zone] is a habit-forming drug in the sense in which the term is applied to alcohol, opium, cocaine, etc. ", and that "no recommendations for further legislative action to prevent the sale or use of marihuana are deemed advisable" [ (46)] . Finally, the New York Mayor's committee on the subject in the 1940s, having given it the most careful study it has received anywhere, concluded that it was neither a significant addiction-producer itself, nor a serious channel to other addictions [ (30)] .

In contrasting these North American opinions it should be remembered that the subjects of the Marcovitz and Charen teams would be inclined to paint a bad picture of their dependency on cannabis, in the hope of receiving army discharge or of escaping punishment, whereas the subjects of the other investigators might be inclined to paint an over-favourable impression in the hope that cannabis might become more easily available.

Elsewhere in the world there is a similar contrast of apparent innocuousness for the average intermittent or light user with something like real addiction in a minority. For Morocco, for instance, Benabud states that in country districts "cannabis addiction shows no signs of being a compulsive need" but that it is a "mass addiction among the urban proletariat" [ 7] . In South Africa "many natives apparently use drugs as the European uses alcohol" and on the same analogy "it is only over-indulgence in drugs which produces the marked mental symptoms" [ (31)] . In India some of the subjects in the Chopras' survey took quite limited doses, found themselves unharmed by it, and could stop when they wanted to, but others, mainly those taking larger doses, felt themselves harmed and yet could not stop. This possible association with the dose or type of drug used is also brought out by North African writers, where hashish is stated to be eight times as strong as kif or ganja, and much more likely to produce addiction [ (8)] , [ (36)] . However, it does not appear that it is the availability of the stronger preparation alone which makes for addiction. In Lebanon, where much hashich for the illegal Egyptian market is reported to be produced, fewer than five addicts a year are admitted to the main Asfuriyeh mental hsopital, although one would expect that popular ideas regarding its innocuousness would lead to many users [ (23)] .

All this does not suggest that the drug by itself induces dependency and addiction in its subject. However, it does offer an escape from the world, and for individuals whose personal inadequacy or social misery are great enough the desire for such escape may lead to a rejection of life without the drug, which is indistinguishable from addiction [ (25)] . And, for the present, cannabis definitely remains a proscribed drug in terms of the WHO Expert Committee's statements and under the laws of many countries.

Long-term psychological effects

As with alcoholism, it is quite difficult to distinguish the longer-term effects of cannabis use from the personality traits or changes which would have been present whether the drug had been used or not. Where the drug is regularly taken, and in considerable quantity, the main characteristic is sloth or lethergy. The stereotype of the habituee in North Africa is the man sitting daylong at his doorstep with his pipe. There are no data to show whether these characteristics are reversible, but Chopra implies that the determination of the chronic smoker is so weakened that natural reversal of the effect after withdrawal of the drug is unlikely. "The psychological treatment; training and education of the addict is as important in the case of cannabis smokers as in opium addicts, in spite of the fact that the physical distress accompanying withdrawal is largely absent" (12 b). But where consumption is less, or more irregular, evidence of chronic mental deterioration is difficult to obtain. The 310 users reported on by Freedman and Rockmore had an average history of 7.1 years use, and yet showed no evidence of mental or physical deterioration [ (20)] . The 67 criminal offenders who were discovered by Bromberg to have been former users showed no characteristics that could be attributed to the drug, although, as might be expected in any criminal population, they did show some psychopathy and a low average I.Q. [ (9)] . In the Army Panama Canal Zone investigation there had apparently been complaints by unit commanders about delinquency or unsoldierly conduct on the part of some users, but the medical commission, after a year's study, thought that these qualities could be adequately.accounted for by the fact that "a large proportion of the delinquents are morons or psychopaths " independently of their taking the drug [ (46)] .

When the drug is consumed regularly in considerable amounts, the main concomitants reported by the Chopras are: insomnia or reduction in normal sleeping time; minor impairments of judgement and memory; limited self-neglect; and on the somatic side much chronic bron- chitis, some asthma, pharyngitis and disturbances of the large bowel [ (12)] . To these must be added, at least as a possibility, the disturbing psychotic and prepsychotic states noted below.

Incidentally, the Chopras noted that although injection of the transverse ciliary vessels is an important sign of ganja use, it remains present for years after the drug has been withheld, and thus is no indicator of recent use [ (12)] .

Cannabis psychosis

Most investigators covered in the present review warn that it is exceedingly difficult to distinguish a psychosis due to cannabis from other acute or chronic psychoses, and several suggest that cannabis is the relatively unimportant precipitating agent only. Thus, Allentuck states that "a characteristic cannabis psychosis does not exist. Marihuana will not produce a psychosis de nova in a well integrated, stable person" [ (3)] . Reales Orozco et al report six cases only doubtfully distinguishable from schizophrenia, alcoholism, etc. (40). The Pretoria investigation noted that "in most of the cases who were diagnosed as dagga psychoses on admission, alcohol has also played its part in producing the mental derangement" [ (31)] . Bromberg calls for more precision in making the diagnosis, using such criteria as "disordered sensorium, characteristic coloured visual hallucinations, time changes" [ (9)] ; but one finds that among the twenty-one cases of psychosis involving cannabis which he discusses in his paper, 7 were clearly functional psychoses merely precipitated by the drug, 7 presented as acute toxic psychoses but got readmitted to mental hospital within two years with a diagnosis of schizophrenia, and one presenting with a similar picture was readmitted with a manic-depressive psychosis. Even with stricter criteria, therefore, the nature of the psychosis remains in doubt. Benabud appears more confident about the diagnosis being made by his psychiatric colleagues in Morocco, and since they have a much greater experience of such conditions than North American psychiatrists this confidence may not be unjustified. However, the clinical data which he presents are unclear, and it is not easy to infer from his paper just what characteristics or patterns are taken as distinguishing a cannabis psychosis from the acute toxic states associated with malnutrition and endemic infection [ 7] . Porot suggests that in North Africa some cannabis psychoses are mislabelled dementia precox, for despite an early and apparently grave onset, some patients with this picture unexpectedly recover (36). However, such acute schizophrenic episodes are found elsewhere in the world, without cannabis being involved, and it is not clear whether the patients referred to are always proven cannabis users, or only assumed to be such.

The cannabis habit 19

In old habitues, several writers have reported a chronic dementia with apparently rather characteristic episodes [ 05] , [ 08] , [ (21)] . The main claims for this are from North Africa, where Aubin claims the evolutional pattern to be quite characteristic [ (5)] . Frazer has reported nine rather different cases from a relatively small number of Indian Army units, and Gaskill found one possible case in an American negro soldier [ (19)] . [ (21)] . In Frazer's cases the men were recognized by their comrades to be untrustworthy, and were apparently rather shunned. Experiencing some deprivation of the drug, they became irritable, showed an outburst of violence, a latent period of apparent normality, and a second outburst of violence followed by acute psychosis if the first warning was not heeded. The symptoms during the psychotic episode were quite similar to those of certain alcoholic psychoses, with terrifying hallucinations, a craving for the drug and filthy or violent behaviour. All the patients recovered within weeks or months, thus differing from the North African cases [ (19)] .

With the diagnosis normally so much in doubt, it is easy to understand that estimates of incidence or prevalence are difficult. The Chopras found 9 cases of frank insanity in 466 cannabis smokers and 4 cases in 772 cannabis drinkers, yielding "active prevalence" rates of 1.93% and 0.52% respectively [ (12)] . Such rates are not much different from the "active prevalence" rates for total psychoses obtained in different community surveys in Europe and North America, rates which range from 0.6% to 2.1% of adult populations. Benabud estimates "recurrent mental derangement" in Moroccan users at 0.5 % [ 7] . The U.S. Army Panama Canal Zone investigation yielded no report of a psychosis arising over a one-year period from what might be estimated to be 500 users [ 46] . Freedman & Rockmore obtained no history of mental hospitalization from their 310 subjects, even though these averaged 7.1 years of usage [ (20)] . Bromberg found no psychosis in the 67 criminal offender users he specifically investigated, and appears to imply that he noticed none in the several hundred other criminal offender users whom he had routinely interviewed [ (9)] . Bouquet for Tunisia states that "victims scarcely ever attain a condition of dementia; it is not in the mental asylums that they are to be found but in the riff-raft of professional beggars, vagabonds and thieves" [ (8)] . For Algeria, Porot would appear to agree (36). Only in Allentuck's sample is the proportion of cases with a history of psychosis high (9 out of 77), but that has little meaning since he located them through hospitals and institutions (3).

The data just cited all refer to any form of psychosis, not to specific cannabis psychoses. Hence, we have the paradox that although it is well established that cannabis use attracts the mentally unstable (see, for instance, the Chopras' finding cited below) the prevalence of majormental disorder among cannabis users appears to be little, if any, higher than that in the general population. Admittedly such data may contain some fallacies, but the techniques used by the Chopras in studying their habituees differed very little from those used in more modern mental health surveys. Therefore, it would appear that true cannabis psychosis must either be very rare indeed, or that it must be substituting for other forms of psychosis. Also, the data raise the question whether the use of cannabis may not be protecting some individuals from a psychosis.

Personality traits of Cannabis users

Becker has pointed out that since cannabis, unlike heroin or cocaine, develops no physical dependence, initiation and an available supply of the drug are not sufficient to lead to habituation. For the initiate, who does not know the dose that would best suit him, first experiences are usually either disappointing or unpleasant and quite frightening. For him to persist, therefore, he must usually have: ( a) encouragement to persist trhough trials until the intended experience is obtained; ( b) encouragement to regard the resultant sensations as pleasurable; ( c) secondary advantages such as a sense of membership of a marihuana-using subculture; ( d) lack of satisfactory contact with disapproving social attitudes or agents; and ( e) lack of competing sources of pleasurable experience that escape cannabis's disadvantages (6 a and b).

For these reasons the isolated user, in contrast to the secret alcohol drinker or morphine addict, is rare, and use tends to be associated with membership of some section of society rather than with individual personality traits. Thus, in some parts of India Brahmins may use cannabis, but high caste Kshatriya (warrior castes) usually do not [ (10)] , [ (12)] . In Morocco cannabis is especially the resort of the underprivileged new urban proletariat [ 7] , but in East and South Africa, although cannabis (dagga) is known, the new urban proletariat turns to alcohol (31). In the United States, where society in general is hostile to cannabis, the user is normally a member of some half-extruded minority group [ (11)] , [ (28)] , but in Mexico, where public opinion is tolerant, it is reported to be used by the normal majority (49). Findings concerning the personality traits of users in one society will not, therefore, necessarily be relevant for other cultures, and in particular the personality traits of North American users are unlikely to be applicable to users in more tolerant lands.

Nevertheless, there are certain characteristics which distinguish the heavyconsumer of cannabis, irrespective of culture. Thus, in North Africa, India and in the United States heavy cannabis consumption is almost exclusively male, and predominantly for the under thirty-five age group [ 7] , [ (11)] , [ (12)] . (The latter observation may be partly an artefact derived from the nature of the various investigator's sources, but at least it would seem that the older habitue draws less attention to himself). In the three territories: again, the heavy user appears to be especially the man in a marginal economic position, cut off from satisfactory family ties and lacking stable residential roots [ 7] , [ (11)] , [ (12)] . One of the striking things about the Morocco survey was the fact that 30 % of patients had changed their residence more than twice within a year [ 7] . Since the habit is both a convivial and a male affair, it is natural that it should attract homosexuals [ (8)] , [ (11)] , and since it tends to produce lethargy or inaction it can be understood to appeal more to the man who seeks to escape from his frustrations than to the man who seeks to break through them. The latter, if he uses cannabis, will customarily combine it with alcohol, but most cannabis habitues avoid alcohol, finding that it spoils the particular sensation which they are seeking [ (9)] [ (51)] .

Because of its hallucinogenic properties, a subgroup of users to be found in most countries is those who seek its aid for religious or semi-religious inspiration. In Africa there was actually a cult insisting on cannabis use (53), and African minority cults in the New World also appear to use or tolerate it. In Brazil, for instance, one of the proposed measures of control of the drug habit was the registration of Afro-Brazilian societies [ (13)] and in Jamaica the Ras Tafari movement and cannabis use have been linked. In India, it is alleged that excessive use of the drug, as opposed to moderate use, is especially to be found in religious mendicants seeking to give an impression of supernatural influence to a credulous public [ (12)] . In North Africa, fakirs may use it similarly, but apparently the true adepts tend to be more moderate in their use [ (36)] .

Neurotic or psychopathic histories are found in many cannabis users, and the Chopras show clearly that where a stronger and a weaker preparation of cannabis are available, subjects with a neurotic history chose the stronger, whereas other subjects tend to choose the weaker [ (12)] . However, whereas in North America the main prior disorders reported tend to be of an antisocial or psychopathic character, in India it is claimed that cannabis users are timid, rarely antisocial in a violent way, and much less of a trouble to their communities than habitual drunkards [ (11)] , [ (12)] . Carstairs contrasts the alcohol consumption of the warrior castes in India with the cannabis consumption of the Brahmin [ (10)] , and Benabud suggests that whereas alcohol suits the European's aggressiveness and dynamism, cannabis suits the Moroccan's mixture of resignation, exaltation and impulsiveness [ 7] .

Other effects

Since this is a psychiatric review it is not intended to cover studies of the other pharmaceutical properties of cannabis except to ask what light, if any, they shed on the centuries-old folk-belief in its medical virtues. The WHO Expert Committee on Addiction-producing Drugs has reaffirmed [ (16)] its opinion that cannabis does not deserve to remain on the pharmacopoeia, since it has no medicinal effect which outweighs its disadvantages or which cannot be substituted for; but this is not to say that the drug has no medicinal properties other than that of intoxication. In fact, the literature of the past decade makes quite frequent mention of other possible effects.

The most interesting of these is an antibiotic effect, recently quite actively investigated in Eastern Europe [ (32)] , [ (38)] , [ (39)] , [ (44)] , [ (54)] , (55), ( 56), (57). It is alleged to be active against gram positive organisms at 1/100,000 dilution, but to be largely inactivated by plasma, so that prospects for its use appear to be confined to E.N.T. and to skin infections. If such an effect were possessed by the crude preparations, it would explain some of the traditional belief in the drug. Two other effects which are also likely to have contributed to the belief and which beyond question reside in the crude preparations are a diuretic effect and an increasing of appetite. The diuretic effect has been described and explored by Chopra and by Ames [ 04] , [ (12)] . The effect appears to be cumulative, to last about 12 hours on a single dose, to be unaccompanied by any abnormality in the urine composition, and to result in the excretion rising to over 2,000 ml [ (12)] per diem. The stimulation of appetite has been described by many experimenters in the U.S.A. [ 04] , (51), and is so well known in India that it is incorporated into proverbs warning that the poor man should not take cannabis lest he eat up his food reserves [ (12)] . As a not unnatural consequence, it has been found that the occasional user looks healthy and well fed, although the habitual user does not.

Less credibly, the drug has apparently been used in China for the treatment of appendicitis [ (26)] .

Pathological somatic sequelae are apparently rare or poorly explored. The bronchitis of chronic Indian smokers [ (12)] is presumably due to the crude smoked material as much as to the specific drugs, but the throat complaints of the same subjects may be a specific result. The Chopras do not believe that it causes asthma, although a number of users have asthma [ (12)] and may have taken cannabis for relief. Porot cites Clérambault as stating that chronic users may develop a penetrating trophic ulcer on the sole (36), and, perhaps as an associated phenomenon, an arteritis has been reported recently from the drug (58). The lethal dose (for Indian The cannabis habit 21 ganja) is about 8 g per kg body weight, whereas the daily consumption of heavy users is rarely above 10 g per adult, so that there remains a wide latitude between customary use and lethal dose [ (12).]

As a combined tonic, diuretic, antibiotic, sedative and pain reliever, then, cannabis appears to have merited its place in folk-lore and in the older pharmacopoeias, with little risk of poisoning or of somatic sequelae. Today it may be true that none of these effects is of sufficient strength and reliability to justify the drug's retention by modern medicine; but at least one can understand why, considering its extreme cheapness, it is still valued by the poor in many countries.

Conclusions

From the above review it is clear that there is still much to be learnt about the effect of cannabis on the human mind. In compiling this review, I have naturally had to stress majority opinions or majority findings, and hence I have probably made the picture more straightforward than it actually is. One meets, in such reading, not only conflicts of opinion, but apparently conflicts regarding observations, and it seems probable that Cannabis has a highly complex influence, dependent on personality and culture as well as on the drug itself. Several of the writers draw attention to our continuing ignorance, and call for better investigations in a society where users are neither facing special problems of adjustment (e.g., adjustment to army life) nor suffering public and legal censure. There is still a need for a properly designed study into the frequency of symptoms at different levels of consumption, such as can be done only by community survey under conditions of unrestricted communication between subject and investigator. The Chopras' investigation most closely approaches what is required, and the wealth of information presented is most admirable; but it is not clear how they obtained their subjects or whether their sample was representative. One has the impression that it was weighted on the side of the heavy user.

Both in the complexity of its effects and in more specific characteristics, cannabis is much closer to alcohol than to the opiates or to cocaine. Like alcohol, it appears to have no deleterious effect on the moderate user, who knows the correct amount for obtaining relaxation or euphoria without additional effects. As with alcohol, single doses given to naive, unstable subjects can produce an acute confusion, perhaps with violence, while the long-term use of heavy doses can probably lead to partial dementia or to an organic reaction type psychosis. Like alcohol, it is alleged to carry no danger for the stable personality, but to attract the neurotic and psychopathic, who are also the people that tend to take the heavy doses. Neither drug has a significant tendency to produce physical dependence; neither drug leads to withdrawal symptoms under normal conditions; and in neither case does desired dosage tend to increase with time. Finally, where the drugs are not prohibited, society's attitude towards the deteriorated chronic user is in both instances one of great tolerance.

There are differences, of course. Cannabis in large doses may be more poisonous, and in small doses it has a more distorting effect on certain mental functions. It is less liable to lead to aggressiveness and antisocial behaviour, but more likely to lead to an asocial passivity. It has a greater variety of medicinal actions than alcohol, and fewer pathological sequelae within the body have been reported, though perhaps only because alcohol has been the more studied.

In this light it is clear that the free availability of cannabis can be harmful, but it is not so clear that this is more harmful than the free availability of alcohol. The question arises, therefore, why cannabis is so regularly banned in countries where alcohol is permitted. One reason may be that, having little direct experience with the drug and hearing the alarming picture reported from countries such as Egypt, these other countries have decided simply to be on the safe side. Another reason may be that the causes of cannabis habituation are confused with its effects. A third reason may be that, because few other pleasures are available to a mass of the people in certain countries, recourse to cannabis there follows the disastrous pattern of the recourse to alcohol in eighteenth-century Britain. One cannot read Benabud's sympathetic description of the Moroccan urban proletariat without realizing that life offers such people very few inducements not to drown themselves in a cannabis illusion. However, there is yet another reason why, I think, alcohol is tolerated in Anglo-Saxon countries while cannabis is feared. It derives from the work ethic of Protestantism and its hostility towards inaction. In India, cannabis can be tolerated and even used by the Brahmin priesthood because social inaction can have a positive connotation, whereas alcohol, with its potential release of repressed impulses, is disapproved of as a disturber and distracter. In Anglo-Saxon cultures inaction is looked down on and often feared, whereas over-activity, aided by alcohol or independently of alcohol, is considerably tolerated despite the social disturbance produced. It may be that we can ban cannabis simply because the people who use it, or would do so, carry little weight in social matters and are relatively easy to control, whereas the alcohol user often carries plenty of weight in social matters and is difficult to control, as the U.S. prohibition era showed. .It has yet to be shown, however, that the one is more socially or personally disruptive than the other.

Summary

The psychiatric literature on cannabis smoking over the past 25 years is quite confused as regards the effects attributed to the drug. However, majority opinion appears to be that cannabis is habit-forming, like alcohol, and not addiction-producing, like opium. It probably produces a specific psychosis, but this must be quite rare, since the prevalence of psychosis in cannabis users is only doubtfully higher than the prevalence in general populations. More important is the mental inertia and lethargy which its use can produce, leading heavy long-time users to resemble chronic deteriorated alcoholics, though with less aggressiveness. Single doses in correct amount produce euphoria, but in greater amount may produce hallucinations or distortion of perception, with hypersensitivity and emotional lability.

The medical reputation which cannabis has in folk-medicine appears to have some justification since, although erratic in action, it possesses a number of valuable properties.

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* The papers of Benabud [ (7)] and of Roland and Teste (42) are largely reproducing one another and it is not clear whose opinions they represent. For simplicity, only Benabud has been referred to here.