Zhang J, et al. - Using a meta-analysis, the physicians evaluated the association between peripheral brain-derived neurotrophic factor (BDNF) levels and attention-deficit/hyperactivity disorder (ADHD). They found that BDNF levels were significantly higher in males with ADHD compared with controls, though there was no significant difference in peripheral BDNF levels between ADHD patients and control groups overall. The outcomes proposed a sex-specific association between peripheral blood BDNF levels and ADHD male patients.