Trajectories of Concurrent Psychological Distress, Heavy Episodic Drinking and Daily Cigarette Smoking From Adolescence to Midlife: Patterns and Their Sociodemographic Correlates.

Aim: The present study examined the joint development and co-occurrence of psychological distress (mainly depressive and anxiety symptoms), heavy episodic drinking (HED) and daily cigarette smoking from adolescence to adulthood. Methods: Data were drawn from two prospective longitudinal cohorts: the TAM study (N = 2194; ages 16-52 years) and the FinnTwin16 study (N = 5563; ages 16-35 years). Latent class analysis identified distinct trajectory groups, and multinomial regression was used to examine associations with sociodemographic factors. Results: Across both cohorts, several trajectory groups emerged: low levels of all three health concerns, high levels of all and high distress with low-to-moderate substance use. In the TAM cohort with longer follow-up time, additional groups included increasing HED and a group indicating moderate levels of all with a peak in daily cigarette smoking. Sociodemographic factors were associated with trajectory group membership. Men were more likely to belong to groups characterized by higher HED and lower distress, while women were more often in groups with higher distress and lower substance use. Participants from non-nuclear families were more likely to belong to groups with elevated substance use or distress. Low parental socioeconomic position was associated with increased likelihood of belonging to high-risk groups in both cohorts. Conclusions: These findings highlight the importance of considering the interplay between substance use and mental health across the life course, as well as the role of early sociodemographic context in shaping these trajectories. Tailored interventions and treatment should account for these differing developmental patterns and background factors.