Effects of methylphenidate on EEG coherence in Attention-Deficit/Hyperactivity Disorder

EEG in adults with Attention-Deficit/Hyperactivity Disorder

“…Although the relationship between EEG activity and intelligence is contentious, there have been no direct links between normal intelligence scores and betweensubject EEG variability (Ellington, 1956;Vogel and Broverman, 1964). A number of studies have also reported that the greatest between-group difference in EEG activity is associated with an AD/HD diagnosis rather than intelligence (Chabot and Serfontein, 1996;Clarke et al, 2001bClarke et al, , 2005. In the present dataset, the effects of IQ were assessed via covariance analyses and found to have no effect on significance levels.…”

EEG coherence in adults with Attention-Deficit/Hyperactivity Disorder

“…From our own laboratory, research has found that AD/HD children have substantial frontal lobe abnormalities with increased coherence in the delta and theta bands (Barry et al, 2002;Clarke et al, 2005;Barry et al, 2005). In the theta band, both intrahemispheric and interhemispheric abnormalities in theta coherence are also found (Barry et al, 2002;Clarke et al, 2005;Barry et al, 2005). In the alpha band, AD/HD children have reduced differences between the hemispheres, and lower intrahemispheric alpha coherences at longer inter-electrode distances than controls .…”

“…Frontally, AD/HD children also had coherences elevated in the delta and theta bands, and reduced in the alpha band. Clarke et al (2005) found that AD/ HD children had lower theta coherences than controls at long inter-electrode distances, and reduced lateralisation at both long and short-medium inter-electrode distances. For interhemispheric comparisons, AD/HD children showed increased coherences in the frontal regions for the low frequency bands (delta and theta), and reduced coherences in the alpha bands in all other regions.…”

EEG coherence in girls with Attention-Deficit/Hyperactivity Disorder: Stimulant effects in good responders

“…Other clinical and empirical studies have found that 80% of patients prescribed these psycho-stimulants showed significant improvements in their core AD/HD symptoms Swanson et al, 1993;Wilens and Biederman, 1992). Clarke et al (2005) was the first study to specifically examine the effects of stimulant medication on EEG coherence in boys with AD/HD. Although the data confirmed characteristic abnormal coherences in AD/ HD, the study failed to find any significant coherence changes attributable to medication.…”

“…Long-distance coherence increases with development of long axonal connections; in contrast, coherence at shorter inter-electrode distances decreases with development due to increases in complexity and competition of interactions within cell populations (Thatcher et al, 1986). There has been substantial support for this model's relevance in children with AD/HD (Barry et al, , 2004(Barry et al, , 2006Clarke et al, 2005Clarke et al, , 2007b. Barry et al (2004Barry et al ( , 2005Barry et al ( , 2006 investigated developmental trends in normal and AD/HD children (aged 8-12) to help develop age-and sex-related coherence norms, and found that cortical coherences develop in a systematic non-linear pattern with age, broadly supporting Thatcher's coherence model.…”