Cerebral Functional Localization Related to Attentional Work in Patients with Attention-Deficit Hyperactivity Disorder

Shin, Dong Won; Song, Dong Ho; Jon, Duk In; Namkoong, Kee; Lee, Man Hong; Lee, Hong Shick; Min, Sung Kil

Abstract

OBJECTIVES: The attentional deficit is a core symptom in attention deficit hyperactivity disorder. The major brain areas related to attention are frontal and parietal lobes. Abnormalities of frontal and parietal lobes in attention deficit hyperactivity disorder have been reported in previous researches. But, most of the researches are based on comparing patients and controls while they are in resting condition. Further research on funtional changes related to performance of attentional task is needed to understand the attentional dysfuntion in attention deficit hyperactivity disorder. In this study, the localized functional changes of the brains related to attentional task in patients with attention deficit hyperactivity disorder and the differences of them between patients and normal controls were examined. Also the effect of the methylphenidate on functional changes related to attentional task in patients with attention deficit hyperactivity disorder was examined. METHOD: Quantitative electroencephalography (QEEG) was applied to examine the fuctional changes related to attentional task. Subjects of this study consisted of 20 patients with attention deficit hyperactivity disorder and 20 controls who were matched age, sex, handedness, intelligence. QEEG was recorded on eye open resting condition, and on performing computerized attentional task. In cases of patients, after taking of methylphenidate, QEEG was recorded on both conditions.
RESULTS
1)In attention test, normal controls had better scores in response time and variabilities of response time than those of patients with attention deficit hyperactivity disorder without taking methylphenidate. After taking medication, scores of omission, response time and variabilities of response time were significantly improved, comparing to scores without taking medication. No differences were recognized between the controls and patients with taking medication in scores of attention test. 2)In resting condition, spectral EEG revealed baseline activity levels of patients were significantly increased comparing to those of controls. 3)Analysis of delta wave revealed that amplitudes of controls were significantly elevated in parieto-occipital area during performance of attentional task. But in patients, localized activated area related to attentional task was not remarkable. 4)Theta activity of controls were significantly elevated in right frontal, right temporal, and both parieto-occipital areas during performance of attentional task. But in patients without taking medication, localized activated area related to attentional work was not remarkable. After taking medication, right frontal, right temporal, and both parieto-occipital areas were significantly activated. 5)Alpha activities of controls were significantly increased in parieto-occipital area during performance of attentional task, but those of patients without taking medication were increased in broad area. 6)Beta activities of controls were significantly increased in frontal area during attentional performance, but those of patients without taking medication were significantly increased in most of the brain areas. After taking medication, significantly increased activities related to attentional task were recognized in left frontal, and both temporal areas. Localized activated patterns similar to those of controls were recognized.
CONCLUSION
Based on the results of this research, it is suggested that patients with attention deficit hyperactivity disorder have increased baseline brain activity. In controls, brains showed localized response to a attentional stimuli, and functional changes related to attentional stimuli were recognized in frontal, and parieto-occipital areas. But, patients failed in showing appropriate localized activated response to attentional stimuli. It is concluded that frontal and parieto-occipital areas have some deficit responsible for the attentional dysfunction of attention deficit hyperactivity disorder.