Cognitive disengagement syndrome: The same as or different from attention-deficit hyperactivity disorder? An examination based on biochemical parameters.

Objectives: The aim of this study was to determine whether there are differences in the biochemical blood parameters between individuals with Cognitive Disengagement Syndrome (CDS) and Attention Deficit Hyperactivity Disorder (ADHD), and to investigate the relationship between vitamin levels and these disorders, as well as their impact on symptom severity.
Methods: The study included 35 patients with ADHD, 35 patients with both ADHD and CDS, and 35 healthy control subjects who presented to the child and adolescent psychiatry outpatient clinic between January 2022 and 2023, matched for age and gender. Children aged 7-15 were included in the study. Participants were administered a sociodemographic data form, DSM-IV Based Screening and Assesment Scale for Disruptive Behavior Disorders- Parent form (DBSAS-DBD) and the Barkley Child Attention Scale (BCAS). Hemogram parameters, iron, ferritin, Thyroid Stimulating Hormone (TSH), T3, T4, and vitamin levels (B12, folic acid, vitamin D) were analyzed for all participants.
Results: Of the participants, 78 (74.3%) were male, and 27 (25.7%) were female. In the analysis, Vitamin B12 and D levels were found to be significantly lower in the ADHD + CDS group compared to both the ADHD group and the control group (p = 0.04; p = 0.03; p = 0.009 p = 0.004 respectively). Hemoglobin levels did not significantly differ between the ADHD + CDS group and the ADHD group, but were significantly higher in the ADHD + CDS group compared to the control group (p = 0.004). Ferritin levels were significantly lower in both the ADHD + CDS group and the ADHD group (p < 0.001; p < 0.001, respectively).
Conclusions: The significant decrease in vitamin B12 and vitamin D in the CDS + ADHD group may be related to daytime sleepiness and slow cognitive processes in the CDS clinic. Screening for nutritional deficiencies in individuals with CDS may be beneficial for clinical management, and identifying differences in blood parameters of CDS from ADHD will contribute to a better understanding of this clinical condition. This is an exploratory study with a rather small sample size, in which many outcomes were examined. Further studies with larger and more diverse samples will provide a more comprehensive understanding of the biochemical foundations of these two conditions.
Competing Interests: Declaration of competing interest I have nothing to declare.
(Copyright © 2025. Published by Elsevier Ltd.)