Effect of methylphenidate on executive functioning in adults with attention-deficit/hyperactivity disorder: normalization of behavior but not related brain activity.
BACKGROUND
We examined the effect of prolonged methylphenidate (MPH) treatment on the functional neuroanatomy of executive functioning in adult men with attention-deficit/hyperactivity disorder (ADHD).


METHODS
Positron emission tomography with [(15)O] water measured alterations of regional cerebral blood flow (rCBF) during the Paced Auditory Serial Addition Task and a control task in 10 ADHD and 11 normal control men. Attention-deficit/hyperactivity disorder men were imaged unmedicated and after a clinically optimal dose of MPH for 3 weeks.


RESULTS
Methylphenidate improved ADHD task performance, reduced rCBF in the prefrontal cortex (PFC), and increased rCBF in the right thalamus and precentral gyrus. Comparisons between the ADHD and normal control groups showed that normal control participants exhibited greater anterior cingulate cortex and temporal gyrus rCBF than ADHD participants under both conditions. Executive functioning was associated with greater subcortical (basal ganglia and cerebellar vermis) activation in the ADHD than normal control group under both conditions.


CONCLUSIONS
Methylphenidate does not normalize task-related activity in ADHD. Task-related rCBF decreases in the PFC may be due to improved filtering out of task-irrelevant stimuli by way of MPH-mediated dopamine release in the PFC.
Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, Maryland, USA. jschweit@mprc.umaryland.edu
Julie B
JB
Schweitzer
Douglas O
DO
Lee
Russell B
RB
Hanford
Caroline F
CF
Zink
Timothy D
TD
Ely
Malle A
MA
Tagamets
John M
JM
Hoffman
Scott T
ST
Grafton
Clinton D
CD
Kilts
D000328:Adult; D019958:Attention Deficit and Disruptive Behavior Disorders / Q000150:complications* / Q000188:drug therapy; D001526:Behavioral Symptoms / Q000188:drug therapy* / Q000209:etiology; D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000187:drug effects; D001931:Brain Mapping; D016022:Case-Control Studies; D000697:Central Nervous System Stimulants / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology* / Q000627:therapeutic use; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography / Q000379:methods; D011340:Problem Solving / Q000187:drug effects*; D012039:Regional Blood Flow; D013647:Task Performance and Analysis
D000697:Central Nervous System Stimulants; D008774:Methylphenidate