Objective: It is aimed to investigate the relation between adult ADHD (attention deficit hyperactivity disorder) subtypes and methylphenidate (MPH) treatment in adult ADHD patients and the changes in N-acetyl aspartate (NAA), creatine and choline levels in anterior cingulate cortex (ACC), cerebellum, striatum and dorsolateral prefrontal cortex (DLPFC) measured by magnetic resonance spectroscopy (MRS).
Methods: Sixty ADHD subjects were included into the study aging between 18 and 60 years. Levels of NAA, creatine and choline in ACC, cerebellum, striatum and DLPFC were measured with MRS. Then, 10 mg oral MPH was given to the subjects and the same metabolite levels were measured after an interval of 30 minutes.
Results: Distribution of the patients according to the ADHD subtypes was as follows: 21 of them (35,0%) were in the inattentive type, 11 of them (18,3%) were in the hyperactive type and 28 of them were (46,7%) in the combined type. NAA levels in striatum after MPH administration in the inattentive type were statistically higher than the ones in the hyperactive type. No difference was determined between the ADHD subtypes in terms of the changes of NAA levels in other brain areas. The difference between ADHD subtypes in terms of the changes of creatine and choline levels before and after MPH was not statistically significant. The decrease of creatine levels after MPH compared to the levels of creatine before MPH in ACC in the hyperactive type patients was statistically significant. The increase of choline levels after MPH compared to the levels of choline before MPH in cerebellum and striatum in the combined type patients were statistically significant.
Conclusion: Consequently, no clear association was found between ADHD subtypes and changes of brain metabolites with use of MPH in adult ADHD.