Objectives The aims were to estimate the association between intelligence measured in young adulthood and risk of alcohol use disorders (AUD) in men and to investigate the potential modification of this association by psychiatric disorders, parental AUD and parental psychiatric disorders.
Design Prospective cohort study based on a linkage of intelligence test scores from draft board examinations and register data on AUD diagnoses during 36 years of follow-up.
Participants 3287 Danish men from the Copenhagen Perinatal Cohort (born 1959–1961) who appeared before the draft board at a mean age of 18.7 years.
Primary outcome measure First registration with AUD during follow-up was the primary outcome. Information on AUD was based on diagnoses retrieved from national hospital and outpatient treatment registers, defined according to the International Classification of Diseases.
Results 361 (11.0%) men were registered with AUD during follow-up. Low intelligence scores were associated with increased odds of AUD adjusting for parental AUD, parental psychiatric disorders, maternal smoking during pregnancy, birth weight, maternal age at birth, parity and childhood socioeconomic position (OR per SD decrease in intelligence=1.69, 95% CI 1.49 to 1.92). Separate analyses indicated significant interaction (p<0.001) between intelligence and psychiatric disorders. The adjusted OR per SD decrease in intelligence score was 2.04 (95% CI 1.67 to 2.49) in men without other psychiatric disorders whereas the OR was 1.21 (95% CI 1.01 to 1.46) in men with other psychiatric disorders. No interaction was found between intelligence and parental AUD or between intelligence and parental psychiatric disorders.
Conclusions The association between intelligence in young adulthood and AUD is modified by other psychiatric disorders as low intelligence is primarily a risk factor for men without other psychiatric disorders. Future studies should take other psychiatric disorders into account when investigating associations between intelligence and AUD.
- Alcohol Use Disorders
- Psychiatric Disorders
- Early Life
- Cohort Study
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Contributors EJ-Ø, TF-M and ELM contributed to the conception and design of the study, performed the data analyses and prepared the first draft. JK, HJS and UB contributed to the interpretation of data and critically revised and reviewed the first draft. All authors read and approved the final manuscript.
Funding This work was supported by Innovation Fund Denmark, Health and Clinical Research (603-00520B).
Disclaimer The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Because our study was register based and did not require any contact with participants, no ethics approval was required according to Danish legislation.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available.
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