The most striking of the use patterns revealed in the National Survey is that 41 % of the adults and 45 % of the youth who have ever used marihuana reported that they no longer use the drug. Twenty-nine percent of the adults and 43% of the youth reported that they are still using marihuana (see Table 1). When asked why they bad terminated use, the overwhelming majority of adults (61%) specified, among other reasons, that they had simply lost interest in the drug.

Table I.-EXPERIENCE WITH MARIHUANA

Percent of ever-users

Frequency Adults Youth Designation

(18 and (12-17)

over)

Have used marihuana but no longer 41 45

u se. lExperimenters.

Once a month or less 9 15

2-3 times pet month 8 10 Intermittent users.

Once per week 4 9 @

Several times per week 5 4 Moderate users.

Once daily 1 1 1

More than once daily 2 4 Heavy users.

No answer 30 12

These data indicate that at least 41% of the adults and 45% of the youth have used marihuana but have -discontinued use; 9% of the adults and 15% of the youth use the drug sporadically, once a, month or less. These persons can be characterized as experimental marihuana users.*

To ensure an understanding of this section of the Report, some definitions are required at this juncture. In this report, the Commission employs the following designations:

Frequency of Use

Experimental-At least one trial to once a month or less.

Intermittent-Two to 10 times monthly.

Moderate-11 times monthly to once, daily.

Heavy-Several times daily.

Very Heavy-Almost constant intoxication with potent preparations; brain rarely drug free.

Duration of Use

Short Term-Less than two years.

Long Term-Two to 10 years.

Very Long Term-Over 10 years.

Twelve percent of the adults and 19% of the youth who have ever used marihuana can be designated intermittent users; they continue to use the drug more than once a month, but less than several times a week, probably on weekends. Six percent of the adults and five percent of the youth are moderate users who continue to use marihuana several times a week to once daily.

Finally, 2% of the adults and 4% of the youth who have ever used marihuana are heavy users: they use the drug several times daily. A very small fraction of these heavy users may be very heavy users, who are intoxicated most of their waking hours and probably use very potent preparations of the drug.

In addition to frequency, duration of use is an important variable in discussing use patterns and especially when considering drug effects. Most users in this country have smoked the drug over a short term, that is, less than two years. Others have used the drug over a long term, two to 10 years. Very few Americans can be considered very long term users, that is, over 10 years.

Another important element of use is the amount of marihuana used on each occasion. Most intermittent and moderate users average about one-half to one cigarette per occasion, usually at night. Most heavy users smoke at least one to two cigarettes an occasion, with a few using as many as five consecutively.

As this brief description of use patterns suggests, marihuana use and the marihuana user do not fall into simple, distinct classifications. Although it is possible to sketch profiles of various marihuana-using populations, no valid stereotype of a marihuana user or non-user can be drawn. The spectrum of individuals who use or have used marihuana varies according to frequency, intensity and duration of use. It is meaningless to talk of "the marihuana user" or "marihuana use" without first clarifying descriptive data.

*All respondents for the National Survey were asked to complete a self administered questionnaire. This instrument covered many sensitive areas, including a series of items on personal experience with marihuana and other drugs. Given the nature of the questions, the contractor took every precaution to insure that the interviewee responded honestly and that his responses were kept strictly confidential. Even the interviewer who orally administered the rest of the Survey was not permitted to view the written instrument.

One of the inevitable costs of such confidentiality is the risk that a certain percentage of respondents would not complete one or more of the questions. Where a significant number of questions remained unanswered, the questionnaire was not tabulated at all. However, in 30%, of the otherwise complete questionnaires, the adult respondents who had ever used the drug did not answer the question, "On the average, about how often do you use marihuana at the present time?"

Concerned about the meaning of this non-response rate, the, Commission directed the contractor to conduct a detailed analysis comparing the non-respondents with all respondents and with those individuals who had never used marihuana at all. On the basis of this analysis, we are confident that the overwhelming majority, if not all, of the non-respondents are experimenters.

In the flrst place, the demographic characteristics of the non-respondents coincide closely with those of the non-users and less frequent users. Very few of the young adults, where more frequent use is concentrated, failed to respond.

Secondly, the non-respondents are disproportionately located in the geographic regions where use was least prevalent and least frequent. For example, 50% of the ever-users in the North Central region failed to respond, compared to 71% in the West. Yet only 5% of the ever-users in the North Central region continue to use the drug more than once a week, compared to 21% in the West; and less than .5% of the ever-users in the North Central region use the drug more than once a day, as compared to 4% in the West.