Appetite hormones, neuropsychological function and methylphenidate use in children with attention-deficit/hyperactivity disorder

Appetite hormones may play a significant role in neuronal excitability and synaptic plasticity and may also affect brain function development. This study aimed to explore the role of appetite hormones in attention deficit/ hyperactivity disorder (ADHD), including aspects of pathophysiology, pharmacotherapy, and side effects. We recruited 119 patients with ADHD who were undergoing methylphenidate treatment (ADHD+MPH), 77 unmedicated ADHD patients (ADHD-MPH), and 87 healthy controls. Blood samples were collected from all participants to examine serum levels of orexin A, ghrelin, leptin, and adiponectin. Behavioral symptoms were assessed using the Swanson, Nolan, and Pelham Rating Scale, and visual and auditory attention were evaluated using computerized neuropsychological tests. The side effects of methylphenidate treatment were measured using Barkley's Side Effects Rating Scale. Orexin levels in the control group were significantly higher than in the ADHD-MPH (p=0.037) and ADHD+MPH (p<0.001) groups; additionally, orexin levels in the ADHD-MPH group were significantly higher than in the ADHD+MPH group (p=0.032). Leptin levels in both the ADHD+MPH (p=0.011) and ADHD-MPH (p=0.011) groups were significantly lower than in the control group. Ghrelin levels were positively associated with auditory attention across all ADHD groups (p=0.015). Furthermore, ghrelin levels were positively correlated with methylphenidate dosage (p=0.024), and negatively correlated with methylphenidate side effects (p=0.044) in the ADHD+MPH group. These findings provide further insight into the relationships between appetite hormones, pharmacotherapy, and ADHD. Orexin A and leptin are associated with the etiology of ADHD, while orexin A and ghrelin play important roles in attention deficits and methylphenidate usage in ADHD.