Low-grade inflammation, cognitive dysfunction, impulsivity, and appetite hormone dysregulation in adolescents with...

Research has identified an inflammatory biotype of attention deficit hyperactivity disorder (ADHD). However, the relation between low-grade inflammation (LGI), subjective clinical symptoms, appetite hormone regulation, and cognitive function in adolescents with ADHD remain unclear.

In all, 88 adolescents with ADHD and 65 healthy adolescents participated in this study. Low-grade inflammation was defined using biochemical criteria (C-reactive protein levels ≥ 3 mg/L) or phenotypic criteria (body mass index ≥ 30 kg/m²). All adolescents answered questions on the Barratt Impulsiveness Scale (BIS) and completed two cognitive tasks: the go/no-go task and the Wisconsin Card Sorting Test (WCST). Parents answered questions on the Swanson, Nolan, and Pelham IV (SNAP-IV) scale for their children's attention and behavior symptoms.

Among the adolescents with ADHD, 16 (18.2 %) were categorized into the low-grade inflammation group. Generalized linear models, adjusted for age, sex, and SNAP-IV scores, revealed that adolescents with ADHD and low-grade inflammation had the highest self-reported overall impulsiveness (BIS total scores; p = 0.006), inattention (BIS-attention subscale scores; p = 0.005), and poor self-control (BIS-self-control subscale scores; p = 0.006). Additionally, this group had the highest insulin (p = 0.003) and leptin levels (p < 0.001) relative to the control group and to the group with ADHD without low-grade inflammation. Adolescents with ADHD and low-grade inflammation, in particular, exhibited poor cognitive performance as measured by the go/no-go task and WCST.

These findings suggest an immune-metabolic subtype of ADHD, indicating that adolescents with ADHD and low-grade inflammation experience more severe impulsivity, disrupted appetite hormone levels, and impaired cognitive function.