Risk factors for attention-deficit/hyperactivity disorder: a case-control study in 5 to 12 years old children

Abstract

Background and aims. Attention deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder known by a pattern of diminished sustained attention and increased impulsivity or hyperactivity. This study aimed to evaluate the risk factors associated with ADHD.

Methods. This case-control study included 297 ADHD children aged 5-12 years admitted to Tehran Institute of Psychiatry, Iran (2012-2013). They were compared with 297 non-ADHD (as controls matched to cases 1:1) who were of the same age (±1 years) selected from outpatients in general pediatric medical centers in Tehran. ADHD Rating Scale IV (ADHD-RS-IV)-Home Version was used to confirm ADHD. Data were analyzed using conditional binary logistic regression.

Results. Mean±SD age were 8.18±3.11 and 8.11±2.9 years in the case and control groups, respectively (P=0.61). Mean±SD birth weight (BW) was higher in ADHD patients compared with the controls (3245.09±0.66 vs 3026.56±0.45 gr, P=0.045). The results showed that odds of ADHD in children with high BW (>3500g) was 3.36 (1.96-5.78) times the odds of ADHD in normal BW children (2500-3500g) controlling for other risk factors. ADHD risk in low BW children (<2500 g) was not statistically different compared with normal BW children [OR:1.74 (0.7-3.7)]. Experience of neonatal disease, fewer offspring, lower level of mothers’ education, and preterm delivery were also risk factors for higher odds of ADHD.

Conclusion. Based on our sample, preterm birth, neonatal disease, high BW, lower level of mother's education, and fewer offspring were ADHD risk factors.