Environmental influences predominate in remission from alcohol use disorder in young adult twins.

Background: Familial influences on remission from alcohol use disorder (AUD) have been studied using family history of AUD rather than family history of remission. The current study used a remission phenotype in a twin sample to examine the relative contributions of genetic and environmental influences to remission.

Method: The sample comprised 6183 twins with an average age of 30 years from the Australian Twin Registry. Lifetime history of alcohol abuse and dependence symptoms and symptom recency were assessed with a structured telephone interview. AUD was defined broadly and narrowly as history of two or more or three or more abuse or dependence symptoms. Remission was defined as absence of symptoms at time of interview among individuals with lifetime AUD. Standard bivariate genetic analyses were conducted to derive estimates of genetic and environmental influences on AUD and remission.

Results: Environmental influences alone accounted for remission in males and for 89% of influences on remission in females, with 11% due to genetic influences shared with AUD, which decreased the likelihood of remission. For women, more than 80% of influences on remission were distinct from influences on AUD, and environmental influences were from individual experiences only. For men, just over 50% of influences on remission were distinct from those on AUD, and the influence of environments shared with the co-twin were substantial. The results for the broad and narrow phenotypes were similar.

Conclusions: The current study establishes young adult remission as a phenotype distinct from AUD and highlights the importance of environmental influences on remission.