Serum Occludin and Zonulin Levels in Children With Attention-Deficit/Hyperactivity Disorder and Healthy Controls.

To evaluate zonulin and occludin levels, potentially associated with immunological pathways in the gut-brain axis, in children with attention-deficit/hyperactivity disorder (ADHD). We examined the association between serum levels of zonulin and occluding, and behavioral/emotional problems in children with ADHD. 40 medication-naïve children meeting Diagnostic and statistical (DSM-5) criteria for ADHD (11 females; mean (SD) age 9.4 (1.6) years) and 39 healthy comparisons (12 females; mean (SD) age 9.3 (1.9) years) were studied. Serum zonulin and occludin levels were measured by (ELISA). We found higher mean (SD) serum zonulin levels [37.1 (28.2) vs 8.1 (4.5) ng/mL; P<0.001) and occludin levels [2.4 (1.6) vs 0.6 (0.4) ng/mL; P<0.001] in the ADHD group compared to control group. Serum zonulin levels had a positive correlation with weight (r=0.452; P=0.003) and BMI (r=0.401; P=0.01) among children with ADHD. Serum zonulin and occludin levels also had a positive correlation with Conners parent rating scale scores (r=0.58; P<0.001), and Strengths and difficulties questionnaire scores (r=0.49; P<0.001). Multiple linear regression analysis revealed that age, sex, weight, conduct problems and oppositional sub-scores were significant predictors of increased serum zonulin levels. These data confirm an association between ADHD, and serum zonulin and occludin levels. Pathophysiological and clinical significance of these findings needs to be elucidated.