The Role of Internalizing Symptoms in Accounting for Intra- and Inter-Individual Variation in Alcohol Use Problems

Abstract

A longstanding hypothesis is that at least some alcohol use problems (AUP) develop and are maintained through the ‘self-medication’ of internalizing (INT) problems – defined broadly as negative affect, inhibition, and symptoms of anxiety and depression. Despite frequent co-occurrence between AUP and INT, evidence for the self-medication hypothesis is mixed likely due to variation in the effect across time and individuals. To address this, three studies were conducted that used different approaches to account for temporal and person specific effects that contribute to the INT-AUP link. Study 1 applied a longitudinal between-person approach to model the effects of INT on AUP over time after accounting for mediating and/or suppressing effects of externalizing (EXT) symptoms (e.g., antisocial behavior, disinhibited personality traits) – another individual differences variable associated with both INT and AUP. Study 2 used a longitudinal, behavioral genetic co-twin control approach to estimate the causal effect of mean-level variation in INT on AUP after controlling for common genetic and environmental liability shared within families. Finally, study 3 examined the degree to which the INT-AUP association is person-specific (i.e., only present for some individuals) along a granular time scale (i.e., day-to-day). Results across studies detected — and replicated — a prospective link between INT and AUP but highlighted that this effect is not uniform across time and individuals. The presence and nature of the INT-AUP link varied across stages of development, individual differences in levels of EXT and familial risk, and even appear person-specific in nature. Future work and clinical applications in this area should carefully account for variation in the INT-AUP across time and individuals.