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7. The Psychology of Cannabis—Techniques for Investigating the Frequency and Patterns of Use of Cannabis in Groups of Drug Users PDF Print E-mail
Written by Ian Hindmarch   
Saturday, 11 September 2010 00:00

7. The Psychology of Cannabis—Techniques for Investigating the Frequency and Patterns of Use of Cannabis in Groups of Drug Users

Ian Hindmarch, Department of Psychology, Leeds University.

This paper reports two studies : both investigations of the frequency and patterns of cannabis use in drug using populations. However, inasmuch as the research area might be identical the techniques used to collect information
are quite distinct and separate. The first study illustrates the use of the self administered questionnaire to collect frequency and patterns of use statistics and, together with information from personal interviews, shows how a consideration of attitudinal variables provides a paradigm for drug using behaviour within cognitive consistency theory. The second study is an essay in participant observation : frequency of use data was again collected together with complete individual histories of illicit drug use.

Before the two research investigations are discussed, a basic consideration of the two methodologies is made, viz, the self administered questionnaire and participant observation.

The majority of research investigations conducted in the United Kingdom regarding the patterns and frequency of use of cannabis by 'normal' populations have utilised the self-administered questionnaire (see Kosviner (1974) in this volume). The self-administered questionnaire has severe limitations in that the behaviour it purports to measure (in this instance patterns of cannabis use) can only be probabilistically inferred from data collected. The analysis and mathematical treatment of data collected from questionnaire surveys is often done with great finesse (Haselton (1974) in this volume) and usually with a high degree of statistical validity, but the computer testing for statistical significance is not able to discriminate whether the data is valid or not. The behaviour associated with illicit drug use is a complex phenomenon and the accurate reporting of the various aspects of this complicated pattern of
behavioural activity will be dependent upon the appropriate response category being contained within the questionnaire. The subjects report of his drug using behaviour is thus limited by the range and suitability of the items contained in the questionnaire. In short, a response box on a questionnaire does not constitute a behaviour analogous to drug use unless the scope of the questionnaire is adequate and the subject is able to make reliable, accurate and valid representation of his behaviour.


Figure 7.1 illustrates how self administered questionnaires relate 'actual' to 'inferred' drug using behaviour and indicates the probabalistic nature of the relationship. However, the efficiency of data collection, with the self-administered questionnaire, in terms of its low 'cost' per unit information make it ideal for administration to large groups. 'Cost'
is not simply an economic measure but embodies a consideration of the time taken and effort required to survey a suitable number of individuals from populations where the transient and ever changing nature of their behaviour necessitates immediate information being collected. Whitehead and Smart (1971) and Somekh (1974) (this volume) have shown student respondents in large scale self-administered questionnaire studies to be internally consistent so adding validity to results derived from such surveys. It is suggested by Somekh (loc. cit.) that a more satisfactory approach to the study of drug using behaviour would be to link data from questionnaires with information from other sources such as individual user interviews or 'prevalence' estimates from doctors and clinics.


The distinguishing feature of this particular mode for the investigation of the patterns of cannabis use is that a social interaction takes place between interviewer (observer) and client (subject). The validity of the procedure rests on the truism that it is easier to train a single observer to record certain criteria behaviour in a reliable manner than to train a large number of naive subjects to make consistent responses to a self administered questionnaire. In the illicit drug using situation the participant observer observes directly the behaviour about him and participates to the extent that he has a durable social relationship with the members of the group about him Vindmarch (1972(a)). Direct observation is the oldest method available to the behavioural sciences and is naturally subjective and qualitative but providing some objective rating scale is used it need not be inaccurate since we assume intraobserver reliability to be high.
Figure 7.2 illustrates the relationship between actual and inferred behaviour - using techniques of participant observation - to be, at least, correlative and certainly meaningful.

One of the main reasons for using an observer to collect basic data is that such a procedure reduces the constraints that arise when respondents attempt to rate their behaviour on a predetermined set of scales, as in a self administered questionnaire. The unique relationship established between observer and subjects also enables the collection of data not normally available to the researcher. Samples of cannabis and data relating to the weighings of cannabis cited in the second study were only possible because of the intimate and mutual relationship of trust established between the group and the observer.


This study reports data collected in 1973 (Einstein, Hughes and Hindmarch (1974) and compares attitudinal profiles collected in 1973 (Hindmarch, Hughes and Einstein (1974)) with profiles collected from a similar population of undergraduates in 1969 (Hindmarch (1970) (1972( b)). A comparison of the 'frequency of cannabis use' statistics collected in 1973 and 1970 is also made.

The raison d'etre of the 1973 study was a test of the allegations from a number of reports purporting a link between the consumption of alcohol, smoking of tobacco and the illicit use of cannabis. The present author (Hindmarch (1970)) - as a result of a participant observation survey of 153 drug users - noted that cannabis users were heavy cigarette smokers. Weitman et al (1972) showed that alcohol and tobacco use correlates with the use of other illicit drugs especially cannabis; and more recently, McKay et al. (1973) concluded that 'drug users' are males who smoke and drink more frequently than the norm.

One thousand names were selected at random from the lists of enrolled students and a questionnaire together with a guarantee of anonymity was mailed to each individual. Personal details (age, sex etc) were collected as well as histories and patterns of cannabis, alcohol and tobacco use. The questionnaire also contained full semantic differential ratings for each drug under consideration and a bank of attitudinal statements derived from previous work ( Hindmarch (1972(c)) with undergraduates.

To validate the questionnaire and to obtain some idea of the reliability of the information offered, respondents were invited to identify their completed questionnaire with a number/letter combination or nonsense word known only to themselves and then attend for personal interview. Some 10 per cent of the respondents identified themselves in this way, the content of their individual interviews confirmed, that for the most part, the questionnaire posed appropriate questions and that subjects were internally consistent. A full analysis of the patterns of use of alcohol, cannabis and tobacco by the 300 respondents to the questionnaire is to be found in Einstein, Hughes and Hindmarch (1974), but certain of the findings are appropriate to this present symposium. There was no significant effect on alcohol consumption due to the use of cannabis, indeed there was a tendency to refrain from the use of alcohol when using cannabis. However, a high consumption of alcohol was associated with a tendency to try, i.e. experimental use of cannabis . There was also a positive correlation between a heavy use of tobacco and the tendency to 'try' cannabis. Table 7.1 presents the summary data for the overall frequency of use of cannabis, alcohol and tobacco.

Table 7.2 is a comparison, using the same criteria of frequency of cannabis use, of data from the 1969 and present studies. It must be emphasised that the present data was obtained via a self administered questionnaire while the 1969 data is from a participant observation study. However, only information from the group of cannabis users is utilised. Essentially of interest is the change in frequency of use of cannabis within a group of cannabis users. It is admitted that a direct comparison of the two groups cannot be made since they are different samples drawn from different populations by different techniques. However, as we will see, evidence from the measured attitudinal profiles of the two samples is consistent with the change in patterns of frequency of use and so a speculative comparison of the two groups is certainly not inappropriate.

Table 7.2 suggests that the overall frequency of use of cannabis by cannabis users has declined between 1969 and 1973. In 1969 the greater proportion (72 per centj of cannabis users were using the drug more frequently than twice a week, while of the 1973 sample of users only 16 per cent had that particular frequency of use. On the other hand, 72 per cent of the 1973 sample used the drug less than once a month, and of these 52 per cent had but an experimental exposure to it; while, only 2 per cent of the 1969 sample had such a low frequency of use.


We have already indicated the reservations to be made in comparing these two groups, but it must also be remembered that we are looking at changes in frequency of use of cannabis in groups of drug users and are in no way establishing prevalence or incidence statistics. The comparison of the two groups also appears more reasonable when we link the frequency of use data with information from attitudinal dimensions collected at the same time from both the cannabis users and from a population of non-drug users of similar age. Table 7.3 compares the 1969 and 1973 groups on the scores produced by the evaluative dimension of Osgood's semantic differential. For a further discussion of this technique see Osgood et al. (1957), Hindmarch (1970)(1972(b)) and Hughes, Einstein and Hindmarch (1974).

The three most salient features of Table 7.3 are

a. the change in evaluation of cannabis by the non-user group from a positive position (66.7) in 1969 to a negative (36.8) position in 1973.

b. the significant attitudinal separation of user and non-user groups in the 1973 sample and

c. in both 1969 and 1973 samples the user groups hold the most positive attitudes.

The 10 cm analogue scale represents exceptionally negative attitudes by a score of zero, exceptionally positive attitudes by a score of 190 and neutrality of attitude by scores in the range 50-7. In 1969 both drug users and non-users had a positive evaluation of cannabis, while in 1973 the non-user group were significantly negative in their evaluation of the drug.

In discussing these findings and defending this particular technique for measuring attitudes a method of cognitive analysis will be used. Festinger (1957) introduced 'cognition' as 'the knowledge, opinion or belief about the environment about oneself or one's behaviour'; and cognitive organisation thus becomes the individuals internal ordering and processing of his behaviour and a major, if not the sole, predictor of future behavioural and motivational action. The contemporary view of cognition is of a dynamic system which interacts with the environment to modify and control behaviour; and central to the function of the system in making decisions are the processes of commitment, choice and justification.


Moreover, there is a basic tendency in human organisms to maintain a consistent view of themselves and their environment. However, in certain situations, the internal (cognitive ) appraisal of self and an external (behavioural) state may be disparate and conflicting: under these conditions cognitive dissonance is generated (Festinger (1957, 1964); Brehm and Cohen (1962)). Dissonance is the result of two or more inconsistent beliefs being held within the same cognitive framework and is defined 'as a general tension state which motivates behaviour, the terminal response of which results in a reduction in the level of tension' (Zimbardo (1969)). We stated earlier that dissonance was produced within a cognitive system, yet we spoke of the conflict between behavioural and cognitive systems i.e. between external and internal states. However, Doob (1947) argued that an attitude is an internal (implicit) correlate of an objective (overt) behaviour system and Campbell (1963) has also shown attitudes to be internal manifestations of behavioural dispositions. Thus, because overt behaviour finds representation in the implicit cognitive state, cognitive dissonance can occur when external behaviour is at odds and incompatible with internal belief systems. Behaviour is modified by experience and, therefore, in order to maintain consistency the correlated attitude must change appropriately. The intimate relationship between attitudinal and behavioural systems is well illustrated by Collins (1968), Steininger (1973) and Wilson et al. (1973). The scope of the present paper curtails any further elaboration on the notional theories of cognitive consistency, but the generality of such an approach in psychology becomes apparent from the scope of Abelson et al's (1968) discursive review of the topic.

The measurement of attitudinal variables is also defended because the author views illicit drug use as a product of drug/society/individual interaction - and the representation of this complex interrelation of variables can be found only in an individual belief system which takes account of the role of environmental factors as well as intrinsic variables of personality, motivation and perception. The appropriateness of attitudinal measures assumes greater importance when one considers the relative failure of 'prone personality' theories (Hill et al. (1960), Gilbert and Lombardi (1967); Halstead and Neal (1968) and Rosenberg (1969) to give consistent views as to the factors which delineate that particular personality structure which is 'at risk'. The lack of evidence attributing the development or escalation of illicit drug use to certain individuals with a 'prone personality' is well illustrated in Mott's (1972) review : she concludes that, individual personality characteristics are 'irrelevant to the study of developing drug misuse because environmental factors are the major determinants of such behaviour'. Furthermore, there is still little agreement between researchers as to which of the many socio-cultural, socio-economic variables are important factors in distinguishing an illicit drug user from his peers (see Kosviner's comparison of U.K. research in this present volume).

The cognitive balance model would predict that as an individual became more behaviourally involved with cannabis his attitudinal system would become more positive in its evaluation of the drug - to maintain congruity between internal and external systems. Table 7.3 did show that cannabis users in both 1969 and 1973 samples held more positive attitudes than non-users. Table 7.3 also shows the tendency for non-user groups to have become more negative in their evaluation of cannabis i.e. the norms of the normal population have 'hardened' and become negative. The causes and origins of such change must needs be speculative but 1969 saw the peak of social activity connected with 'flower power', 'psychedelic music' and 'hippies' and between 1969 and 1973 there has been a great deal of information often conflicting about the botany, chemistry, pharmacology and psychology of cannabis. This information, from a wide variety of scientific and non-scientific sources was disseminated via underground and conventional newspapers and presses.
Teratogenic, psychotomimetic, carcinogenic and hallucinogenic effects were attributed to use of the substance cannabis. Contemporaneous with reports of these negative effects much was written about the relaxing, positive, creative and enhancing effects of the drug. Thus before an individual could take cannabis he would have to resolve the dissonance between the various opinions presented to him, i.e. is cannabis harmful or not? If he decided cannabis was harmful he might not try cannabis, but if he did try it he would certainly not escalate to an intense chronic level of drug use. The behavioural concomitants of these cognitive decisions are to be found in Table 7.2 - i.e. the less frequent (chronic) use of cannabis by drug users in 1973.


Furthermore we would expect that an increased behavioural involvement with the drug would intensify the related attitudinal component. Figure 7.3 shows that as an individual progresses towards a more frequent use
of cannabis so his attitudes become more positive. These later figures are consistent with notions of behaviour/ attitude congruity and recent work (Martino and Truss (1973)) which has shown on a variety of measures that attitudes to cannabis were positively related to actual cannabis use. Also of importance (Figure 7.1) is the significant difference (pc-.7.0.001) between non-users and experimenters and between experimenters and casual users in the attitudes they hold towards cannabis. These differences tend to contradict notions of drug use escalation based on a developing pharmacological tolerance since, before an individual can progress from an experimental level of cannabis use to a more persistent level he must overcome an 'attitudinal barrier'. The 1973 sample (Fig.7.3) analysis also shows the 'non-user' to be separated quite distinctly from the 'experimenter' in terms of his evaluation of cannabis.

We have shown earlier that a change in overt behaviour, in this instance frequency of cannabis use, was paralleled by a change in attitudinal valence. An attitudinal valence is regarded as a product of the individual personality but it also embraces the result
of environment - organism interaction and other contingent environmental factors relating to past, present and even future behaviour.

The individuals attitudinal framework is his internal cognizance of his external behavioural world. It is important for the integrity of his cognitive system, that personal attitudes and beliefs are not inconsistent or dissonant with overt behaviour. The notion that tension
or stress is generated when behaviour and belief systems contradict each other or produce disharmony and conflict has been shown to be widely held within psychology (Aronson 1968). It is hypothesised that certain individuals maintain their cognitive integrity by adopting an attitudinal framework which prohibits either an escalation of drug use, or in the case of non users, a commencement of drug use. These individuals could be regarded as internally consistent, in that they maintain their belief system by endogenous as opposed to exogenous factors.On the other hand there are individuals who tend to maintain cognitive consistency by altering their attitudinal framework to fit the change in their own behaviour in the external situation. They therefore place greater reliance on exogenous as opposed to endogenous factors. Such individuals having reached a particular level of cannabis use (in our tables, that of casual use) have to adjust their attitudinal system to take account of the change in overt behaviour, otherwise their attitudes would be dissonant with their behaviour. Once this cognitive conflict has been resolved, i.e. the attitudes restructured, then an increase in the frequency of cannabis use can be tolerated (even to a chronic level) without overt behaviour being inconsistent or dissonant with the new attitudinal framework. If, however, they cannot restructure their cognitive framework, then the only way they can maintain consistency and prevent conflict from arising is to reduce their overt behaviour (cannabis use) to an appropriate level in order to balance their internal beliefs with their drug using behaviour. Two distinct groups of individuals are represented in this present study. The first being internally consistent, do not allow dissonance i.e. conflict between beliefs and actual behaviour to occur, these are the non-users and experimenters. The second group of casual and more frequent users tend to reduce their dissonance by changing their attitudinal framework, and so we observe the increase in positive evaluation of cannabis as concomitant with the increase in reported frequency of cannabis use.

Of further interest is the polarised attitudinal separation of non cannabis users from cannabis users of all levels. We have also shown that earlier research (iindmarch (1970)) found the attitudes of both users and non-users of cannabis to be positively biased; and since the 1973 data was collected from a similar population of undergraduates we postulated a 'hardening' of attitudes in the non-using group. Arguably this is for a variety of reasons; but, it is suggested that the vast amount of conflicting information regarding cannabis and its effects produced over the previous four years has been sufficient to produce conflict and dissonance in the attitudinal system of potential users. In order to reduce this dissonance and return their cognitive system to an integral harmonious state, individuals have relied on endogenous norms. In other words, cognitive consistency is maintained by regarding it as 'dangerous', in general, to use a drug about which so much conflicting evidence is presented.

The attitudinal separation of the non-cannabis user from the cannabis user is also an effective 'barrier' to starting cannabis use. Even if a non-user takes cannabis once or twice, say at a party or other social gathering, then he is still unlikely to become a more frequent user because he holds a relatively negative set of attitudes compared with those using cannabis more frequently.

Since it is expected that persons need to be 'consistent' in their attitudes they hold then we would expect fewer individuals constantly restructuring their framework to maintain parity with overt behaviour. So we expect fewer chronic and persistent cannabis users than experimenters and this was confirmed in this present sample (Einstein, et al., 1974) and is in accord with results of recent surveys of students (Smart and Whitehead, 1973).


In establishing frequency of use statistics via questionnaire methods, the measure used is invariably the number of joints smoked per unit time. Such measures usually preclude any estimate of cannabis use by means other than smoking, and frequently take no account of the relative potency of the cannabis used or the dose administered.

The following research shows the relationship of dose, potency and frequency of cannabis use to general parameters of psycho-social behaviour. Any such psychopharmacological study has antecedent, dependent and consequential variables associated with the phenomenon described and measured (Hindmarch (1972(d)). In the present instance antecedent variables concern the chemical and botanical description of cannabis together with measures of dose levels and mode of administration. Situational, emotional and attitudinal variables will also produce an effect at this level. Dependent variables concern the psychological, physiological and pharmacological effects of cannabis administration. Consequential variables, such as the terratogenic, therapeutic and creative effects of cannabis use lie outside the scope of this discussion.

One of the most important sets of antecedent variables are those associated with situation, motivation and emotion. Since the present study involves individuals 'at large' in society as members of a drug using 'subculture' these variables are bound to be influencing the observed behaviour, but are impossible to isolate. No attempt at manipulation or control of these situational variables was attempted since Jones (1971) demonstrated how awareness of drug induced states is shaped by companions and environment. Subjects filled out a subjective drug effects questionnaire following solitary smoking of 9 mg of THC and similarly completed a questionnaire following participation in a group of four persons each smoking 9 mg of THC. Subjects in the group situation had a significantly greater rating of the degree of euphoria and the amount of perceptual and cognitive effects than did the same subjects under solitary conditions. The reverse trend was noticed for dysphoria, i.e. a greater feeling of dysphoria was experienced under solitary conditions of cannabis administration. Significantly enough, in view of the comments above on social setting, Jones (op.cit) reported '... subjects frequently commented that it was difficult to make valid judgements because of the laboratory setting.'

Furthermore, Miras (1972) and Hindmarch (1972(e)) have commented upon the heightened suggestibility of persons under marijuana intoxication, and have also shown the importance of the group situation in modifying the effects of drug intoxication.

Therefore, the behavioural effects of cannabis use are not only a product of the drug and the immediate physical environment in which the drug is taken, but are also influenced by the particular values of the subcultural group to which the cannabis users belong. Naturally the interaction between these several sources of situational variance is complex but there is no doubt that such variables must be accounted for in any cannabis evaluation performed in man.

The placebo effect is well known in man and mention has already been made of the role of other users on the subjective effects of cannabis when taken in a group situation. The 'social high' phenomenon is well documented (Rodin et al. (1970)) and providing the 'set' to experience marijuana effects is sufficiently great, subjects given a placebo do report 'feeling high', 'relaxed', 'a loss of sense of time', and 'feeling more at peace with the world'. (Jones (op.cit)).

The most positive attitudes held by cannabis users towards cannabis (Hindmarch (1970)) undoubtedly play a major role in determining the effects experienced by individual users. The 2-THC content of some samples of herbal mixture seized by police drug squads would not be sufficient to induce any psychological effects. However, large quantities of low THC content marijuana are being used daily with most users experiencing a 'high'. Evidence also suggests that totally inert mixtures of 'gum arabic and curry powder' (Hindmarch (1970)) and 'powdered glass and incense' (Fairbairn, Hindmarch et al. (1974)) passed as cannabis can produce typical euphoric reactions when taken by experienced users.

Although Weil et al. ( 1968) assert that only practiced users get high and only practiced users can differentiate between placebo and drug effects. Jones' work on the subjective rating of marijuana effects showed that practiced users were no more effective in judging potency of placebo and drug samples than were a naive population. However, Kiplinger et al. (1972) showed that under conditions of constant setting, the effects reported by naive and semi-naive observers were significantly related to the dose level of e-THC administered.

Contact with the group of drug users was established using a snowballing technique (Polsky (1971)) and observations were made and data collected from the group using the techniques of participant observation (Hindmarch (1972(a)). Initial contact was established in the Summer of 1969 and maintained until the Autumn of 1972, and it is only because of the long lasting rapport established and mutual confidence gained that the following information was able to be collected.

The group comprised 58 (42 a" 169) subjects all of whom had a history of illicit drug use. However, the large group divided into two distinct sub-groups. The first comprising 25 (18e 59) members were persistent and habitual polydrug users (cannabis, hallucinogens, amphetamines, barbiturates and wide experience of prescribed and proprietary medicines, opiates and cocaine); the second group with 33 (240'99) members had a history of polydrug experimentation, but had since September 1970 used only cannabis ( with the exception of a rare and most infrequent use of L.S.D.). The two sub-groups were further distinguished on social behavioural parameters. Eight of polydrug using group (60'29) had a history of psychiatric disorder and two males were then under treatment. Five male subjects had been convicted and fined under the drug abuse legislature and a further male respondent had served a term of imprisonment for drug offences. Only twelve (100' 29) members were in full time employment or completing college education, the remaining thirteen relying on part time jobs or social security benefits to support them. There was also a persistent history of delinquency, minor civil offences (non payment of rent, hire purchase contracts etc) in nine of the group.

By contrast, none of the cannabis using group had ever sought psychiatric help because of their drug use and none had a history of psychiatric disorder. All of the group, bar four married women, were either in full-time employment or completing full-time vocational or college courses. None of the group had been charged by the police for drug offences and the only record of delinquency was a 'shop lifting' offence against one of the female respondents some five years ago.

It is the second group of cannabis users that concerns us here. In order to estimate the quantity of cannabis consumed; the group provided, between September 1970 and May 1972, the weight of cannabis (either resin or herbal) consumed during a 24 hour (10a.m. - 10a.m.) period. The cannabis was weighed on a portable 'top-pan' balance prior to use and the weighings represented, therefore, only the cannabis consumed during the 24 hour sample period and not the weight of cannabis possessed by the group. The author or an 'informant' in the group kept a record of the number of people present in the drug using situation which enabled the calculation of the mean weight of cannabis used for each individual during a typical day. The sample days for the weighings were chosen randomly before the collection of data began and all but four were in accord with this principle. As a partial check on the accuracy of the above procedure and to obtain samples for analysis the group was visited 17 times over and above the usual observational sessions. These visits and 3 samples volunteered from the group account for the reefer samples 15 to 28 in the following tables. Five of the reefers collected (15, 22, 25, 26, 27) contained samples of the cannabis weighed during the previous 24 hour sample period. The samples volunteered from the
users were collected either 'made up' in cigarette form or were pro-reefers in that the sample supplied was sufficient, when mixed with tobacco to produce a typical reefer. All samples were coded and sent for qualitative and quantitative analysis. Behavioural observations recorded at the time were related to the analytic results via the code number of the sample. The results of the analysis of the cannabinoid content of the reefers together with data from a similar study in London, is reported in full elsewhere (Fairbairn, Hindmarch et al. (1974)).

Table 7.4 shows the results of the sample day weighings of cannabis; and Table 7.5 gives the mean daily use of reefers of known cannabinoid content. Table 7.6 gives details of the contents and components of the sample reefers.


Table 7.4 shows the average amount of cannabis consumed per person per day to be 2.8 G. This mean amount is not as important as the wide range of daily dose levels (0.3 G to 12.0 G) and the variety (herbal, resin or mixture) of cannabis consumed. Of interest is the range of modes of administration, and while smoking is predominant eating and cooking are also reported. On sample day 10, 6.4 G of herbal cannabis was infused with water in a coffee percolator for some 20 - 30 minutes, but no samples were collected. However, the group kindly repeated the performance and supplied samples of the infusion and residue for analysis. The tea contained 0.039 mg of THC, a surprisingly low level considering that the preparation was highly valued by the users who claimed the effects of drinking such 'tea' to be 'gentler' and 'higher' than the smoking of an equivalent amount of herbal cannabis. Most users with experience of ingestion of resin or herbal mixtures either in their raw state or when cooked in fudge, stews or biscuits reported the slower onset of drug effects. The subjective effects were rated more like L.S.D. experiences when the drug was ingested in this manner. The 'high' experienced by the herbal tea drinkers is yet another example of the placebo effect and it appears that even habitual users are quite susceptible to such effects.

Table 7.5 shows the frequency of use of reefers of known cannabinoid content and indicated the average daily dose of THC per user for the range of samples collected. It is realised that the figures for 'THC consumed' do not represent the dose actually received by the individual. Variations in individual metabolic state, loss of active compound in smoke and 'air stream', number of individuals passing joint, variations in individual smoking habits etc alter the amount of active compound received by the individual. However, even if the individual THC consumption figures are not accurate measures of the dose actually received, they do illustrate the great variability in amount of active compound taken by these users. The net effect of these different sources of variance makes the establishment of any dose response relationships difficult, if not impossible. The following individual effects-relating to the reefers enumerated in Table 7.5 do show, however, a tenuous dose-behaviour relationship.

The general pattern of smoking for the majority of the group was usually one reefer during the working day, perhaps at lunchtime, following by a further one or two reefers during the evening. The frequency of use increases somewhat at weekends, and it is usually at weekends that cannabis is ingested or used in cooking. Upon such occasions the individuals present each bring small quantities of cannabis for communal use, and it is not surprising that it is at weekends that the group exhibits noticeable effects of cannabis use.


Reefer No.15: The individual admitted that he could not smoke more than one a day, usually in the evening. On the occasion that he smoked a similar reefer to the one analysed during his lunch break he had to absent himself from his employment because he was to quote 'smashed' and unable to coordinate his movements. He is usually alert during the working day but tends to be more withdrawn at weekends when he occasionally smokes two or three reefers per day. He is essentially isolated within the group and even though he is known and liked by most of the others, he prefers his own company.

Reefer No. 22: Two married couples regularly smoke, between them, twenty similar reefers daily. They also use the resin in cooking and have produced a variety of sweetmeats and biscuits containing cannabis. The most characteristic feature of the two female subjects is a persistent hilarity neither are in full-time employment, and they spend most of their time about the flat habited by both couples. The two males appear generally to be somnolent, detached and a little hesitant in their
speech when answering questions.

Reefer No. 27: Are used habitually by two small sub groups which vary between 3 and 8 members. The daily frequency of use for any one individual is between 3 and 5 reefers. None of the users exhibit any noticeable disorganisation of the cognitive processes and seem entirely capable of holding full time employment. On occasions some of these users have reported lapses of memory, e.g. forgetting to alight from a bus at the appropriate stop, missing appointments and not posting letters. The most noticeable feature of the above individuals and other members of the group is their apparent 'introversion' and partial detachment from their immediate environment. They all seem more or less withdrawn and somnolent, and most noticeable is the difficulty they experience in placing recent events in their correct temporal order. To a certain extent their perception of time is distorted and minor lapses in short term memory are sometimes obvious. However intentional actions, complex perceptual motor skills, e.g. car driving seem unaffected by their habitual cannabis use.

In terms of these observations it would appear that the habitual chronic use of cannabis can make individuals withdrawn, detached, apathetic and lacking intent. However, since all these subjects are coping with normal everyday experiences it would seem that the soporific effects of cannabis are limited to reducing the need to interact with the environment, since there is no impairment of function when interaction is intended, or the behaviour sufficiently motivated. (see also Abel (1970)).


Two interesting observations are made in Table 7.6. The sample (no.15) comprised local grown leaf. The following horticultural details were supplied by the grower ...'the plants were grown from the seeds of Zambian 'bush' germinated in March in pots and transplanted at a height of 9" outdoors in medium clay soil on a well drained embankment with a southern aspect. The plants were cut down in September before flowering by which time they had attained a mean height of 8'.". Perhaps the sample is rich in THC because of its freshness and the apparent lack of CBD is in accord (assuming the seeds to be from Zambia) with Turner and Hadley's (1973) recent results. The relatively high THC content of this sample tends to contradict assertions that potent cannabis cannot be grown in the temperate climate of the U.K., and since this sample contains leaf only it falls outside the present international definition of cannabis as 'the flowering or fruiting tops of the cannabis plant excluding the seeds and leaves when not accompanied by the tops'; as presented in the Single Convention on Narcotic Drugs 1961 (see also Fairbairn et al (1971)). Sample 28, on the other hand, contained no active cannabinoid whatsoever and comprised a mixture of ground glass and vegetable matter (which turned out to be incense). The subject who used a similar concoction believing it to be Turkish pollen Hashish for which he had paid £18 per ounce, did not experience euphoria but complained of nausea and headache. However, the same substance when used by three other group members ( dose, frequency etc unknown) produced (to quote) 'the usual effects'.

Clearly this research is incomplete and few conclusions can be drawn about the generality of the patterns of use reported here. The wide variation of dose, frequency of use, mode of administration and potency are worthy of further consideration. Such variability does imply that the number of joints used per unit time is not a good index by which to classify an individual as a drug user at a particular 'level of use'.

This paper has presented two particular approaches to the study of the patterns and frequency of cannabis use. Each approach produces unique data, but it is hoped that future research could be mounted to combine the two techniques and so enable more definitive statements to be made about the psychological effects of cannabis administration in man.


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A recurring theme of concern to some participants was the comparability of his two university student samples, and the meaning which one could derive from the fact that reported frequencies of use in these two populations of ever-users differed. Since the two samples were not identical, there was some doubt that the lower frequencies of use reported in the later sample could be taken as indicative of any real change in pattern of use over time.

This concern over matching, and over whether observed differences might be artifacts of lack of matching of samples, has already been noted in connection with Dr Soueif's paper.

Dr Someck congratulated Dr Hindmarch on his paper, and asked 'Do you really believe that the differences between your 1969 and 1974 samples were really not differences in sampling?'

Dr Hindmarch: 'There are lots of reasons why there are differences. There are differences in the samples, there are differences in the way that I actually generated the two samples and in the techniques used to collect the information. However the comparison of the two samples in terms of theories of cognitive consistency seems justified since the difference in level of use parallels a difference in attitude. Furthermore, information collected by participant observations suggested a decrease in 'chronic' cannabis use in the area.'


Dr Miller asked about the ways in which the amounts of cannabis used were determined, and pointed out some differences between amount likely to be absorbed into the body in different conditions of use. In one study carried out for the LeDain Commission, fourteen regular (3-4 times per week) users in their twenties were asked to weight all drugs used and to submit samples for analysis. 'The range of THC consumed ranged from 1 mg. per session up to more than 50 mg in a few instances, and the sessions ranged from one up to twelve hours. The median was about 7 mg THC, and alcohol use was used in about one third of the sessions. There is quite strong evidence from other studies in North America that typical doses are from 2 to 8 mg. Laboratory work indicates that with a tightly controlled smoking paradigm which maximises delivery, retention and absorbtion, about 6 mg put regular (several times a week) users slightly higher than where they prefer to be.'

With reference to cross cultural comparisons, Dr Miller said that 'There are pronounced differences in the style of smoking in different countries. In those countries where the total THC consumption per day is very high, for instance Jamaica and India, the style of smoking is one of puffing. In Jamaica, they roll very large spliffs, and they just puff and puff and puff, so much that sometimes you can hardly see the smoker. So he's running through huge quantities of cannabinoids, and then throwing away large roaches, which probably contain a large percentage of the total cigarette weight. They probably absorb a relatively small percentage of total used. But in North America, the smoking style is very anal-retentive, the whole roach is consumed, and retention and absorption is much higher.'

Dr Hindmarch said that the smoking style in the UK was comparable to that in North America.

Dr Tinklenberg reiterated the importance of looking at styles of smoking, puffing rate, length of butt in determining the amount of THC actually absorbed. 'And I would like to point to research in the area of tobacco, which I think has established quite clearly that consciously or unconsciously the heavy user learns how to modify his consumption of tobacco in order to maintain a certain level of absorbed nicotine.' Both Dr Tinklenberg and Dr Miller believed that these were issues worth bearing in mind in future research of the kind Dr Hindmarch described, which was well worth while. Dr Rathod agreed and drew a parallel in quoting the style of use in India in which there was no control of dose after ingestion.


The editors would like to add that the tightness with which the cigarette is packed affects its rate of burning. A more loosely packed joint may burn more quickly, when more will literally go up in smoke between puffs, and less into the lung. Also , more economical use of the joint may occur in a large group, since the ratio of puffing to free burning may be higher then. In a small group, and more particularly with a solitary user, continuous puffing is most unlikely for any length of time unless the joint is extremely weak. Thus the percentage of THC smoked that is actually absorbed may be lower in solitary users than in group using situations.


Dr Edwards suggested that attitudes to cannabis might have to be broken down a little more to be most meaningful. In connecting with some current research into drinking, it is clear that one has an overall evaluation of alcohol, but that really is not all that predictive
or meaningful. 'There is an attitude to me drinking, and an attitude to somebody else drinking, and to women drinking, and toward older people drinking, and younger people drinking. And then there are attitudes towards getting drunk as opposed to drinking. And you can invite people not to put one mark on a line to indicate their attitude, but to put marks to show their area of uncertainty. Suddenly you find how asking for only one point on a line has denied your subjects' potential to express what they mean. It may be very important as an indicator of the instability of somebody's position to give them an opportunity to express their area of uncertainty.'


Dr Hawks suggested that it was very important to note that relationships between, say attitudes and behaviour in a sample generated in one manner might be quite different from the relationships between attitudes and behaviour generated in another manner. Dr Hindmarch agreed that such a proviso applied to his study.

Dr Edwards expressed his interest in longitudinal studies to discover whether people's stated attitudes to cannabis are predictive of their later behaviour.

Mr Dorn reported that the ISDD's work had shown that tte semantic differential did clearly differentiate between non-user with and without drug-using acquaintances in terms of their perception of the 'drug user'. He asked whether these differences in attitude were perhaps the result of the respondent's social location and affiliations. Could one talk of attitudes being predictive of future behaviour, or was the relationship the other way round (meeting a user and thinking - he's not so bad)?

Dr Hindmarch replied that he believed behaviour to be largely directed by the environment in childhood, and by the established attitude system in adulthood. Mr Dorn suggested that such a change-over to 'internal' control might never occur: adults might simply have and respond to a more static environment. Research in this area should look at the hypothesis that a change in social experience and behaviour influences attitudes, and well as the hypothesis that attitudes mould behaviour.


Drs Miles and Tinklenberg asked about costs of cannabis in the UK, and there was some discussion of the difficulties of estimating this. The editors estimate that if a slightly short ounce of 25 gm of resin of 5 per cent THC is bought at a cost of £15 (the current UK price range is about £12-18 per ounce), then the cost per milligram is just over one penny. Since cost goes up for buying in smaller lots than one ounce, we could say that 10 mg THC would cost about 20 pence.

Last Updated on Wednesday, 29 December 2010 23:33

Our valuable member Ian Hindmarch has been with us since Wednesday, 29 December 2010.