Neurophysiological methods testing the psychoneural basis of attention deficit hyperactivity disorder

Abstract

Theories concerning the etiology of attention deficit hyperactivity disorder have evolved from the 1950s, when it was believed that an injury to or dysfunction of the diencephalon was the cause of the syndrome, to the present day, when delayed brain maturation is postulated as an explanation. Delay in laying down myelin can be investigated by newly developed techniques like computerized EEG and transcranial magnetic stimulation. In this study, a group of 15 children 3-7 years of age suffering from attention deficit were investigated using both methods in combination and were compared to a control group of 23 age-matched normal children. On the computerized EEG spectral analysis significant differences to the control group were found in areas O1 and O2 (P < 0.05, Student's t-test). With transcranial magnetic stimulation, the overall difference in right/left stimulation was statistically significant (P < 0.001). The results suggest delayed myelination at the brain stem reticular formation where the alpha rhythm is activated and at the corticospinal pathway as parts of a widespread involvement.

The circumplex model of affect: An integrative approach to affective neuroscience, cognitive development, and psychopathology

“…Consistent with the circumplex model of affect, several investigators have noted that ADHD, bipolar disorder, and anxiety disorder are all characterized by hyperarousal (Biederman & Spencer, 1999;Swann, Katz, Bowden, Berman, & Stokes, 1999). Indeed, aberrant patterns of activation within arousal systems of the CNS have been noted in physiological studies of persons with these disorders (Mefford & Potter, 1989;Skinner et al, 2004;Ucles, Lorente, & Rosa, 1996). Delayed myelination of the RF, for example, has been suggested in children with ADHD in findings from a transcranial magnetic stimulation study (Ucles et al, 1996).…”

“…Indeed, aberrant patterns of activation within arousal systems of the CNS have been noted in physiological studies of persons with these disorders (Mefford & Potter, 1989;Skinner et al, 2004;Ucles, Lorente, & Rosa, 1996). Delayed myelination of the RF, for example, has been suggested in children with ADHD in findings from a transcranial magnetic stimulation study (Ucles et al, 1996). Individuals with anxiety disorders demonstrate excessive activations of their amygdala when viewing fearful faces and phobic objects (Rauch et al, 2003), and morphological abnormalities of the amygdala have been reported in adolescents and adults with bipolar disorder (Blumberg, Kaufman, Martin, Whiteman, Gore, Charney, Krystal, & Peterson, 2003;DelBello, Zimmerman, Mills, Getz, & Strakowski, 2004).…”

"Maturational lag" hypothesis of attention deficit hyperactivity disorder: an update

“…The patterns of quantitative EEG abnormality observed in children with ADHD are in the form of either an excessively slow activity (mostly delta and theta in the frontal regions, especially in the anterior regions) (64-66) or a decrease in alpha activity (which could reflect delayed maturation in the alpha rhythm circuits) (67). These findings of an age-inappropriate increase in slow activity in ADHD/HKD children could reflect either a maturational lag, which could be normalized with age, or a deviation of brain maturation in ADHD/ HKD children and adolescents compared with normal controls.…”

Comparison of the Inhibitory and Excitatory Effects of ADHD Medications Methylphenidate and Atomoxetine on Motor Cortex

“…TMS has been used to study cortical changes in ADHD (Buchmann et al, 2003;Gilbert et al, 2004a;Moll et al, 2001;Ucles et al, 1996) and is sensitive to the effects of many drugs (Daskalakis et al, 2002;Ziemann 2004), including those affecting monoaminergic systems. TMS is a noninvasive, welltolerated (Garvey et al, 2001), safe (Gilbert et al, 2004b), and easily replicated (Gilbert et al, 2005) procedure for studying the physiological state of neural circuits in the human motor cortex.…”