Changing Patterns of Recent Substance Use in Emerging Adulthood and Their Associations With Cognitive Functions and...

Emerging adulthood is a developmental period marked by heightened risk for illicit substance use, potentially influencing neurocognitive development and mental health. However, longitudinal and objective data on changing patterns of substance use and their associated neuropsychiatric outcomes remain scarce. Longitudinal monitoring of substance use could inform targeted prevention strategies during this sensitive developmental period.

This Swiss longitudinal cohort study included 731 emerging adults. Hair concentrations of >100 psychoactive substances and metabolites were assessed at ages 20 and 24 years. Latent profile analysis was used to derive profiles of change in recent substance use. Regression models examined associations with cognitive functioning (attention, working memory, declarative memory, composite score) measured at age 24 using the Cambridge Neuropsychological Test Automated Battery and mental health symptoms assessed at both ages 20 and 24 using the Social Behavior Questionnaire.

Among participants with substance use at either time point (n = 440), 5 distinct change profiles were identified: low/decreasers (n = 288, 65.5%), cannabis increasers (n = 48, 10.9%), club drug increasers (n = 40, 9.1%), medical stimulant increasers (n = 43, 9.8%), and medical sedative increasers (n = 21, 4.8%). Compared with participants with no hair-tested substance use (n = 291), cannabis increasers showed lower attention (d = 0.34) and elevated anxiety-depressive (d = 0.53) and attention-deficit/hyperactivity disorder (ADHD) (d = 0.38) symptoms. Club drug increasers performed worse on attention (d = 0.41) and composite cognitive scores (d = 0.39). Medical sedative increasers showed lower attention (d = 0.74), working memory (d = 0.58), and composite cognitive performance (d = 0.76). Medical stimulant increasers showed markedly elevated ADHD symptoms (d = 0.82).

Emerging adults' profiles of change in recent substance use were associated with specific cognitive and mental health risks.