Plasma dopamine and noradrenaline levels in children with attention deficit and hyperactivity disorder

Objective: Attention deficit hyperactivity disorder (ADHD) is an important psychiatric disorder due to its prominent effects on the patients’ and their families’ quality of life, with a 5% prevalence worldwide. Although the pathogenesis of ADHD is still largely unknown, evidences derived as results from many studies focus primarily on dopaminergic and noradrenergic systems. The aim of this study is to determine plasma dopamine (DA) and noradrenaline (NA) levels of the cases diagnosed with ADHD at the pre- treatment process and to compare these levels with DA and NA levels of the healthy control group.

Method: Fifty children with ADHD and 50 healthy children between ages 6-12 were included in the study. Psychiatric diagnoses were determined by using Kiddie Schedule for Affective Disorders and Schizophrenia for School Aged Children- Present and Lifetime Version (K-SADS- PL) as semi-structured clinical interview and plasma DA and NA levels were measured before the initiation of treatment. Cases’ parents were asked to fill in Child Behavior Checklist for ages 4-18 (CBCL) and Dupaul ADHD scale while their teachers were asked to fill in Conners Teacher Rating Scale- short form. ADHD symptom severity was measured by Clinical Global Impression scale (CGI).

Results: No statistically significant difference was found for NA levels between case and control group while there was a borderline statistically significant difference for plasma DA levels (p=0.990 and p=0.05, respectively). No statistically significant difference was found, when plasma DA and NA levels were compared for ADHD subtypes in the case group (p=0.390 and p=0.213, respectively).

Conclusion: Evidences regarding neurobiological causes that may affect the emergence of ADHD support the possible roles of catecholaminergic pathways over cognition and movement. Getting a better understanding of the possible roles of catecholaminergic and non-catecholaminergic systems in ADHD might help in both getting a better grip of the disorder and determining better treatment regimen that shall target the disorder.