Chronotypical features of children with attention deficit and hyperactivity disorder and its association with microrna levels

Background: Attention deficit hyperactivity disorder is one of the most common disorder in child and adolescent psychiatry with approximately %5-7 prevelance. It comprises of attention deficieny, hyperactivity and impulsivity component. Etiology of the disease is multifactorial. There are genetic, neurochemical, neuropsychological, neuroanatomical and enviromental factors. In studies conducted with individuals who have ADHD, it has been shown that their chronotypical preferences are different from healthy normal individuals. This result indicates that there may be some circadian rhythm problems in this multifactorial etiology of ADHD.In the regulation of circadian rhythm , genes like CLOCK and BMAL1 and associated microRNAs take charge. In our study, we compared children with ADHD and healthy control group according to chronotypical choices; their miR-142-3p and miR-378 levels which are linked to BMAL1 gene. Methods: It has been chosen 50 children with ADHD who have diagnosed according to DSM and 44 healthy children for this study. Childhood Chronotype Survey was used to determine chronotypical preferences of children. Blood samples has taken at 9 am to evaluate in genetic laboratory for measuring serum miR-142-3p and miR-378 levels. Results: Children with ADHD has shown activeness at night(eveningness). Beside; this feature has found associated with ADHD in both groups. Psychopathology of mother is associated with ADHD existence in our study (p:0.003) but there has been no significant relevance between father psychopathology of father and ADHD existence (p:0.372). There has been no statistically significant difference in miR-142-3p (p:0.97) and miR-378 (p:0.063) levels between two groups. A specific group in children with ADHD which has a family member possess any psychiatric disease, has decreased level of miR-142-3p (p: 0.011, rho: 0.37) and miR-378 (p:0.017, rho:0.38) compared to controls. Conclusion: We have found that circadian rhythm in children with ADHD slips to eveningness mostly and eveningness is related to ADHD. The difference between parent s psychopathology difference gives us rise to thought that maternal psychopathology could be important in genetic transferance of ADHD. In previous studies, it has been proven that miR-142-3p and miR-378 levels are associated to BMAL1 gene. However in our study, we could not found any statistically significant difference in miRna levels between controls and children with ADHD who have more problems in circadian rhythm. But a specific group in children with ADHD which has a family member possess any psychiatric disease has decreased miRNA levels and this result may explain miRNA levels can be linked to genetic burden. Key words: miR-142-3p, miR-378, ADHD, Chronotype, Circadian rhythm