Central stress allostasis among deprived and continuing marijuana users and non-users

Objective: We examined central nervous system stress allostasis (i.e., stress responses) among deprived and continuing heavy marijuana users and non-users. Method: Participants (N=210; 46.7% female; mean age=21.99; 91.4% White, 94.3% Non-Hispanic) were heavy marijuana users (N=134) and non-users (N=76). Heavy users were randomly assigned to a 3-day marijuana deprivation condition (N=68) or to continue using regularly (N=66). Participants completed 2 threat-of-shock stressor tasks that manipulated stressor predictability by varying shock probability or timing. We measured central stress allostasis via startle potentiation (stressor conditions minus matched no-stressor condition). We examined two group contrasts (heavy use: all heavy users vs. non-users; deprivation: deprived vs. continuing heavy users) on startle potentiation overall and moderated by stressor predictability (unpredictable vs. predictable). Results: Deprivation did not affect startle potentiation overall (timing task: p=0.184; probability task: p=0.328) or by stressor predictability (timing task: p=0.340; probability task: p=0.488). Heavy use did not affect startle potentiation overall (timing task: p=0.213; probability task: p=0.843) or by stressor predictability (timing task: p=0.683; probability task: p=0.348). Post-hoc analyses showed a general startle reactivity X deprivation interaction on startle potentiation overall (timing task: p=0.019; probability task: p=0.056) and by stressor predictability in the probability task (p=0.022) but not in the timing task (p=0.374). Conclusions: A history of marijuana use or acute deprivation did not alter central stress allostasis despite prominent theoretical expectations. This study adds to growing research on central stress allostasis in individuals with a history of drug use and begins to parse moderating roles of individual differences and stressor characteristics.