UC San Diego

Background and aims

Anhedonia-a transdiagnostic psychopathological trait indicative of inability to experience pleasure-could lead to and result from adolescent marijuana use, yet this notion has not been tested. This study aimed to estimate the association of: (1) anhedonia at age 14 with rate of change in marijuana use over an 18-month follow-up, and (2) marijuana use at age 14 with rate of change in anhedonia over follow-up. Secondary aims were to test whether gender, baseline marijuana use history and peer marijuana use moderated these associations.

Design

Observational longitudinal cohort repeated-measures design, with baseline (age 14 years), 6-month, 12-month and 18-month follow-up assessments.

Settings

Ten public high schools in Los Angeles, CA, USA, 2013-15.

Participants

Students [n = 3394; 53.5% female, mean (standard deviation) age at baseline = 14.1 (0.42)].

Measurements

Self-report level of anhedonia on the Snaith-Hamilton Pleasure Scale and frequency of marijuana use in the past 30 days.

Findings

Parallel process latent growth curve models adjusting for confounders showed that baseline anhedonia level was associated positively with the rate of increase in marijuana use frequency across follow-ups [β, 95% confidence interval (CI) = 0.115 (0.022, 0.252), P = 0.03]. Baseline marijuana use frequency was not related significantly to the rate of change in anhedonia across follow-ups [β, 95% CI = -0.015 (-0.350, 0.321), P = 0.93]. The association of baseline anhedonia with faster marijuana use escalation was amplified among adolescents with (versus without) friends who used marijuana at baseline [β, 95% CI = 0.179 (0.043, 0.334) versus 0.064 (-0.071, 0.187), interaction P = 0.04], but did not differ by gender or baseline ever marijuana use.

Conclusions

In mid-adolescence, anhedonia is associated with subsequent marijuana use escalation, but marijuana use escalation does not appear to be associated with subsequent anhedonia.