Age at onset and age at treatment of alcohol use disorders: Associations with educational level and intelligence

Associations of educational level and intelligence with age at onset and age at treatment of alcohol use disorders (AUD) are sparsely investigated; however, knowledge about these associations is important for an enhanced understanding of AUD. This study aimed to examine three measures of timing of AUD: estimated age at onset of alcohol problems, age at first registration in an outpatient alcohol clinic, and age at first AUD hospital diagnosis, and to estimate associations of educational level and intelligence with each measure of timing of AUD. The aims were investigated in a register-based study comprising 7,019 Danish men seeking outpatient AUD treatment. Data on educational level and intelligence were obtained from the Danish Conscription Database. Estimated age at onset of alcohol problems and age at first registration in an outpatient alcohol clinic were obtained from the Copenhagen Alcohol Cohort. Age at first AUD hospital diagnosis was retrieved from national Danish psychiatric registers. Among individuals with information on all measures of timing of AUD, 65.8% followed the developmental sequence: estimated age at onset of alcohol problems (M = 32.08 years, SD = 9.3), age at first registration in an outpatient alcohol clinic (M = 39.89 years, SD = 9.5), and age at first AUD hospital diagnosis (M = 42.27 years, SD = 12.4). Adjusted linear regression models revealed significant associations of high educational level and high intelligence with later onset and treatment of AUD, ranging from 0.61 to 0.89 years (p < 0.0001) for educational level and from 0.10 to 0.09 years (p < 0.0001) for intelligence. In conclusion, AUD develops sequentially. High educational level and intelligence were associated with later onset and treatment of AUD, but educational level explained most unique variance. This may indicate that in addition to cognitive factors reflected by both educational level and intelligence, non-cognitive factors only reflected by educational level also are important for the timing of AUD.