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This study examined the moderating effect of social and coping motives on distress among young cannabis-using adults. A random sample of 2031 young Swiss adults was interviewed by means of a computer-assisted telephone interview. Cannabis users showed more distress, less positive health behaviour and higher hedonism compared to non-users. Taking motive for use as a moderator variable into consideration, it became evident that only cannabis users with coping motives showed lower mental health, more symptoms of psychopathology, more psychosocial distress and more life events than non-users. Young adults with social motives for use on the other hand did not differ from non-users in terms of distress. These differences between cannabis users with social and those with coping motives remained stable over two years. In both subgroups, participants with regular cannabis use at baseline did not increase distress nor did participants with higher distress at baseline increase the frequency of their cannabis use. Our results suggest that secondary prevention for cannabis users should target especially young adults with coping motives for use.

Cannabis use is widespread among adolescents and young adults. In the majority of cases, cannabis use is age-limited and given up once adulthood is reached, with new professional responsibilities, marriage or parenthood. Many emerging adults even with excessive cannabis use do not develop long-term drug-related problems (Arnett, 2005 and von Sydow et al., 2001) and many studies did not find any association between less frequent cannabis use and mental disorders or other drug-related problems (Degenhardt et al., 2003, Degenhardt et al., 2004, Patton et al., 2002 and Poulton et al., 2001). However, numerous publications show that addicted high-dose cannabis use over several years significantly increases the risk of psychosis (Andreasson et al., 1987, Van Os et al., 2001, Verdoux, 2004 and Zammit et al., 2002), depression or anxiety disorder (Bovasso, 2001, Degenhardt et al., 2003, Degenhardt et al., 2004 and Patton et al., 2002). The specific mechanisms underlying these associations need to be explored further and may differ in different age groups. Not only regular high-dose cannabis use but also infrequent, recreational cannabis use was found to be associated with psychological problems. Fergusson, Horwood, and Swain-Campbell (2002) revealed an association between cannabis use and other illegal substance use, delinquency, depression and suicidal behaviour and a frequency of use that is less than once a month. Degenhardt, Hall, and Lynskey (2001) found an association between a higher rate of anxiety and affective disorders and a frequency of use of once every second month. Brodbeck, Matter, and Moggi (2005) found that in a representative sample of 5448 Swiss adolescents aged 16–18, cannabis use of once a month was associated with higher psychosocial distress, more physical complaints, less positive attitude towards life, more smoking and more regular alcohol consumption. Cannabis use of 1–2 times per week was related to higher scores of depression compared to no or less frequent use. It is important to identify subgroups of young cannabis users who do not show adverse effects of cannabis use and subgroups, who are at greater risk to develop harmful effects on mental health or health behaviour at an early stage in order to understand the dynamic of cannabis use and to design effective preventive intervention. Established risk factors for problematic cannabis use associated with psychosocial harm are higher frequency of use, lower onset age, lower onset age of regular use, longer length of use, mental disorders (von Sydow et al., 2001) and fewer psychosocial resources (Huesler, Werlen, & Plancherel, 2004). However, at present it cannot be said with certainty which psychological characteristics of cannabis users, which pattern of infrequent use, or which interaction between these factors correlate with a non-problematic use of cannabis and do not bear a risk of future drug-related problems. Analysing the reasons for cannabis use however, may be an important step towards understanding the association between cannabis use and its adverse effects and thus towards tailoring effective interventions to achieve behaviour changes (Simons, Correia, Carey, & Borsari, 1998). Furthermore, different functional roles of and reasons for cannabis use may be instrumental in shaping different patterns and different contexts of use, which in turn may be associated with a different level of drug-related problem. As established in this and many other studies the main reasons for use are the enhancement of positive affects, the expansion of experimental awareness, social conformity, social cohesion motives, and the reduction of negative affect (Newcomb et al., 1988 and Simons et al., 1998). Age-specific reasons for cannabis use among emerging adults are identity exploration, encouragement by substance-using friends to foster the integration in a peer group, or to relieve feelings of distress caused by identity confusions and age-related instability (Arnett, 2005 and Silereisen and Reese, 2001). Simons et al. (1998) found that social motives for cannabis use and non-coping motives were a significant predictor of negative consequences of cannabis use. Chabrol, Duconge, Casas, Roura, and Carey (2005) concluded in a cross-sectional study that the motives for use were more important than psychopathology in predicting cannabis use in adolescents and young adults. To provide a better understanding of the factors that discriminate problematic and non-problematic cannabis use, the present study focuses on the motives for cannabis use and their association with mental health and psychosocial distress. We will analyse the development of psychopathology and psychosocial distress over two years among young cannabis users with coping and social motives, who continued using cannabis. Additionally we include a higher frequency of use and a lower psychosocial adjustment at baseline as risk factors for problematic cannabis use. To our knowledge motives for cannabis use have not yet been analysed as moderator variables of mental health and psychosocial distress among cannabis users in a longitudinal non-clinical random sample. If the motive for use is a moderator variable of distress among cannabis users, we should two subgroups of cannabis users who differ in terms of mental health, psychopathology, psychosocial distress and life events. We tested the following hypotheses. 1) Cannabis users with social motives show a better mental health, lower psychopathology and psychosocial distress and less life events than participants with coping motives. 2) Cannabis users with social motive level of distress do not differ from non-using persons. 3) Cannabis-using young adults with higher distress scores at baseline increase their frequency of cannabis use over two years only when they use cannabis for coping reasons. 4) A higher frequency of cannabis use at baseline increases distress at follow-up only among cannabis users with coping motives.