Central stress response among deprived and continuing marijuana users and nonusers.

Abstract

Objective: We examined central nervous system [CNS] stress responses among deprived and continuing heavy marijuana users and nonusers. Method: Participants (N = 210; 46.7% female; M age = 21.99; 91.4% White, 94.3% Non-Hispanic) were heavy marijuana users (N = 134) and nonusers (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 two threat-of-shock stressor tasks that manipulated stressor predictability by varying shock probability or timing. We measured central stress responses via startle potentiation (stressor conditions minus matched no-stressor condition). We examined two group contrasts (heavy use: all heavy users vs. nonusers; 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 = .184; probability task: p = .328) or differently by stressor predictability (timing task: p = .147; probability task: p = .678). Heavy use did not affect startle potentiation overall (timing task: p = .213; probability task: p = .843) or differently by stressor predictability (timing task: p = .655; probability task: p = .273). Posthoc analyses showed mixed evidence of general startle reactivity × deprivation interaction on startle potentiation overall (timing task: p = .019; probability task: p = .056) and differently by stressor predictability (probability task: p = .024; timing task: p = .364). Conclusions: A history of marijuana use or acute deprivation did not alter central stress responses despite prominent theoretical expectations. This study adds to growing research on central stress responses in individuals with a history of drug use and begins to parse moderating roles of individual differences and stressor characteristics. Public Health Significance StatementIndividuals with a history of drug use have been theorized to display atypical stress responses. This study does not find evidence of altered CNS stress responses when comparing heavy marijuana users to nonusers or when comparing continuing marijuana users to acutely deprived marijuana users. Expanding research to include naturalistic stressors, more stressor characteristics, and multisystemic responses may improve understanding of stress mechanisms in substance use disorders and offer paths forward for theory refinement and treatment.