Birth conditions and attention deficit/hyperactivity disorders (ADHD) in adults in the Pelotas (Brazil) birth cohorts of 1982 and 1993

This study evaluates the association of birth con-ditions with attention deficit/hyperactivity disor-ders (ADHD) in adults using data from two birth cohorts in the city of Pelotas Rio Grande do Sul State, Brazil. In 1982 and 1993 all births in the city were identified and have been prospectively monitored. In the follow-ups at 30 and 22 years of the 1982 (n = 3,574) and 1993 (n = 3,780) cohorts, respectively, participants were examined, and trained psychologists applied the Mini -Interna-tional Neuropsychiatric Interview (M.I.N.I.). Those individuals who met the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnostic criteria were defined as positive for ADHD. Poisson regression with robust variance adjustment was used to estimate the prevalence ratio (PR) adjusted for sex, maternal skin color, family income, maternal age, maternal school-ing during pregnancy, maternal marital status, parity, and maternal smoking during pregnancy. The prevalence of adult ADHD was 4.4% and 4.5% in the 1982 and 1993 cohorts, respectively. The prevalence of ADHD was higher in those born with lower weight, but no linear trend was ob-served, and those born with weight between 3,000 and 3,499 grams (PR = 1.40; 95%CI: 1.05-1.86) had the highest risk. For gestational age, we ob-served an inversely proportional relationship for the presence of ADHD: preterm infants had a 33% higher risk (95%CI: 0.90-1.96) of being considered as having ADHD than those born at 39 or more weeks, but as the confidence interval included nullity, this association may have occurred at random. These results indicate that birth weight and gestational age may be associated with adult ADHD.