Intelligence in young adulthood and alcohol use disorders in a prospective cohort study of Danish men: the role of psychiatric disorders and parental psychiatric history.
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.


SETTING
Denmark.


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.
['Just-Østergaard|Emilie|E|0000-0003-1073-5046', 'Flensborg-Madsen|Trine|T|', 'Knop|Joachim|J|', 'Sørensen|Holger Jelling|HJ|', 'Becker|Ulrik|U|', 'Mortensen|Erik Lykke|EL|']
D000293:Adolescent D000328:Adult D000437:Alcoholism D015331:Cohort Studies D003718:Denmark D005260:Female D005500:Follow-Up Studies D006801:Humans D007360:Intelligence D008297:Male D008423:Maternal Age D008571:Men D001523:Mental Disorders D008875:Middle Aged D010290:Parents D010298:Parity D011247:Pregnancy D011248:Pregnancy Complications D011446:Prospective Studies D012307:Risk Factors D012907:Smoking D012923:Social Class D055815:Young Adult
Intelligence Alcohol Use Disorders Cohort Study Psychiatric Disorders Early Life