Comorbidity and temporal ordering of alcohol use disorders and other psychiatric disorders: results from a Danish register-based study.

BACKGROUND: Understanding the comorbidity of alcohol use disorders (AUD) and other psychiatric disorders may have important implications for treatment and preventive interventions. However, information on the epidemiology of this comorbidity is lacking. The objective of this study was to present results on lifetime psychiatric comorbidity of AUD in a large Danish community population.
METHODS: A prospective cohort study was used, comprising 3 updated measures of sets of lifestyle covariates and 26 years of follow-up data on 18,146 individuals from the Copenhagen City Heart Study, Denmark. The study population was linked to national Danish hospital registers and a greater Copenhagen alcohol unit treatment register to detect registrations with AUD and other psychiatric disorders.
RESULTS: Of the individuals invited to the study, 7.6% were registered with AUD, and among these, 50.3% had a lifetime comorbid psychiatric disorder. Personality disorders were the most common comorbid disorders (24%) together with mood disorders (16.8%) and drug abuse (16.6%). The risk of developing a psychiatric disorder in individuals who were already registered with AUD was larger than the risk of developing AUD in individuals who were already registered with another psychiatric disorder; these differences in risk were especially noticeable for anxiety disorders, personality disorders, and drug abuse.
CONCLUSIONS: AUD is frequently comorbid with other psychiatric disorders, and it is likely that AUD is both an etiologic factor in other mental disorders and a consequence of mental disease. However, in interpreting these complex and perhaps circular causal links, it is important to consider that AUD is registered before a comorbid psychiatric diagnosis more often than the reverse temporal order.