The influence of methylphenidate on the power spectrum of ADHD children - an MEG study.
BACKGROUND
The present study was dedicated to investigate the influence of Methylphenidate (MPH) on cortical processing of children who were diagnosed with different subtypes of Attention Deficit Hyperactivity Disorder (ADHD). As all of the previous studies investigating power differences in different frequency bands have been using EEG, mostly with a relatively small number of electrodes our aim was to obtain new aspects using high density magnetoencephalography (MEG).


METHODS
35 children (6 female, 29 male) participated in this study. Mean age was 11.7 years (+/- 1.92 years). 17 children were diagnosed of having an Attention-Deficit/Hyperactivity Disorder of the combined type (ADHDcom, DSM IV code 314.01); the other 18 were diagnosed for ADHD of the predominantly inattentive type (ADHDin, DSM IV code 314.0). We measured the MEG during a 5 minute resting period with a 148-channel magnetometer system (MAGNES 2500 WH, 4D Neuroimaging, San Diego, USA). Power values were averaged for 5 bands: Delta (D, 1.5-3.5 Hz), Theta (T, 3.5-7.5 Hz), Alpha (A, 7.5-12.5 Hz), Beta (B, 12.5-25 Hz) and Global (GL, 1.5-25 Hz).). Additionally, attention was measured behaviourally using the D2 test of attention with and without medication.


RESULTS
The global power of the frequency band from 1.5 to 25 Hz increased with MPH. Relative Theta was found to be higher in the left hemisphere after administration of MPH than before. A positive correlation was found between D2 test improvement and MPH-induced power changes in the Theta band over the left frontal region. A linear regression was computed and confirmed that the larger the improvement in D2 test performance, the larger the increase in Theta after MPH application.


CONCLUSIONS
Main effects induced by medication were found in frontal regions. Theta band activity increased over the left hemisphere after MPH application. This finding contradicts EEG results of several groups who found lower levels of Theta power after MPH application. As relative Theta correlates with D2 test improvement we conclude that MEG provide complementary and therefore important new insights to ADHD.
Wienbruch
Christian
C
Clinical Psychology, University of Konstanz, Konstanz, Germany. Christian.Wienbruch@uni-konstanz.de
Paul
Isabella
I
Bauer
Susanne
S
Kivelitz
Hermann
H
D000513:Alpha Rhythm / Q000187:drug effects / Q000706:statistics & numerical data; D001288:Attention / Q000187:drug effects / Q000502:physiology; D001289:Attention Deficit Disorder with Hyperactivity / Q000145:classification / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000494:pharmacology / Q000627:therapeutic use*; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D002648:Child; D003344:Cortical Synchronization / Q000187:drug effects / Q000706:statistics & numerical data; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004569:Electroencephalography / Q000187:drug effects / Q000706:statistics & numerical data; D005260:Female; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D006801:Humans; D015225:Magnetoencephalography / Q000187:drug effects*; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology / Q000627:therapeutic use*; D011569:Psychiatric Status Rating Scales; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D013826:Theta Rhythm / Q000187:drug effects / Q000706:statistics & numerical data; D014796:Visual Perception / Q000187:drug effects / Q000502:physiology
D000697:Central Nervous System Stimulants; D008774:Methylphenidate