Body mass index and height in young adult men in relation to subsequent risk of mood disorder

Adolescence represents an important period in brain and mental development, which raises the question of whether measures of body size at entry into adult life influence the risk of developing mood disorders. We examined the association of BMI and height in a cohort of young men with risk of mood disorders throughout life. The study included 630,807 Danish men born 1939-1959 and 1983-1997 with measures of height and weight at conscription board examinations. Psychiatrist's diagnosis of mood disorders was obtained from national patient registries from 1969 to 2016. The associations of BMI and height with mood disorders were estimated by Cox proportional hazard regression analyses adjusting for education, cognitive ability, migration status drug and alcohol misuse. During a mean follow-up of 26.3 years, 2,608 (0.6%) and 19,690 (3.1%) men were diagnosed with bipolar disorder and depression, respectively. We found an inverse linear association of BMI with risk of bipolar disorder, whereas the association of BMI with depression was curve-linear with a decline in risk until BMI around 25 kg/m(2), and an almost constant risk across the BMI range above 25 kg/m(2). Height was not associated with bipolar disorder or depression. Comparison of brothers, assumed to share family factors of possible influence on the risk of mood disorders, showed similar results although with wider confidence intervals. BMI in the lower range at men's entry into adulthood is inversely associated with risk of bipolar disorder and depression throughout adult life, whereas height is not related.