High Catalase and Low Thiol Levels in Adult-ADHD Patients

Objective: The prevalence of Adult attention-deficit/hyperactivity disorder (A-ADHD) has been estimated as to be around 5%. There are several hypotheses regarding the etiology of ADHD. Although numerous researches have been conducted regarding neurobiology of pediatric ADHD, A-ADHD studies were relatively few. Many studies have indicated that oxidant mediated neuronal damage may play a role in the pathophysiology of various psychiatric disorders. Recently, oxidative stress has been studied in A-ADHD and there is an accumulating evidence to support its' role. In the present study, we aimed to evaluate catalase (CAT) and thiol levels in A-ADHD patients and compare with healthy controls. Materials-Methods: Twenty-five A-ADHD patients from Gaziantep University, diagnosed according to Turgay's Turkish version of Adult ADD/ADHD DSM IV-Based Diagnostic Screening and Rating Scale by two psychiatrists, and 25 healthy volunteer controls were included. The subjects strictly refrained from any substance intake and physical exercise after 08:00 p.m. on the day before collection. CAT and Thiol levels were measured in plasma samples of study groups. Results: Age, gender, and body mass indexes of patients and controls have shown homogeneity and there were no differences between the groups. Total score and subscores were not correlated with any of the mentioned biochemical parameters. The mean CAT levels in patients with ADHD were significantly higher and Thiol levels were lower than those of controls (<0.001, <0.001, respectively). When the comorbid patient group compared with pure A-ADHD patients in terms of CAT (11.49 +/- 0.28, 11.51 +/- 0.40, respectively) and thiol (0.22 +/- 0.05, 0.25 +/- 0.03, respectively) levels there were not found any significant differences (p=0.865, p=0.174, respectively). Conclusions: The results of the present study may indicate that thiol levels may be decreased with in reaction of increased CAT levels and thiol act like a pro-oxidant. This study may be considered as one of the initial phase studies that lighten the relationship between oxidative stress and A-ADHD.There is a need for further studies that will prove this relationship exactly.