Neurophysiological Subtypes Research Articles

EEG-Based Personalized Medicine in ADHD: Individual Alpha Peak Frequency as an Endophenotype Associated with Nonresponse

This review article summarizes some recent developments in psychiatry such as personalized medicine, employing biomarkers and endophenotypes, and developments collectively referred to as neuromodulation with a focus on ADHD. Several neurophysiological subtypes in ADHD and their relation to treatment outcome are reviewed. In older research the existence of an ‘‘abnormal EEG’’ or ‘‘paroxysmal EEG’’ was often reported, most likely explained by the high occurrence of this EEG subtype in autism, as the diagnosis of autism was not coined until 1980. This subgroup might respond best to anticonvulsant treatments, which requires more specific research. A second subgroup is a beta-excess or beta-spindling subgroup. This group responds well to stimulant medication, albeit several studies suggesting that neurophysiologically this might represent a different subgroup. The third subgroup consists of the ‘‘impaired vigilance’’ subgroup with the often-reported excess frontal theta or excess frontal alpha. This subgroup responds well to stimulant medication. Finally, it is proposed that a slow individual alpha peak frequency is an endophenotype related to treatment resistance in ADHD. Future studies should incorporate this endophenotype in clinical trials to further investigate new treatments for this substantial subgroup of patients, such as NIRSbiofeedback, transcranial Doppler sonography biofeedback, hyperbaric oxygen therapy, or medications such as nicotine and piracetam.

Guillain-Barre syndrome and Campylobacter jejuni infection

Guillain-Barre syndrome (GBS) is the most common cause of acute neuromuscular paralysis, usually due to acute inflammatory demyelinating polyradiculoneuropathy. The presence of activated T lymphocytes and antibodies against peripheral nerve myelin suggests an autoimmune pathogenesis, although there is wide heterogeneity. Gangliosides are sialylated glycolipids widely distributed in nervous system membranes. GBS is usually preceded by an infection, most frequently Campylobacter jejuni enteritis, but also cytomegalovirus, Mycoplasma pneumoniae or Epstein-Barr virus. Patients with GBS and C. jejuni infection are more likely to have neurophysiological features of axonal neuropathy, antibodies to ganglioside GM1, pure motor GBS, a less elevated CSF protein concentration and a worse outcome than other GBS patients. Although molecular mimicry between peripheral nerve gangliosides and epitopes present on C. jejuni lipopolysaccharide could explain some of these associations, this hypothesis is inadequate to account for many aspects of the pathogenesis of GBS.

Prediction of treatment outcome in cocaine dependent males using quantitative EEG

This study investigates the existence of outcome related neurophysiological subtypes within a population of abstinent cocaine dependent adults. We have previously reported and replicated the existence of a distinctive quantitative EEG (QEEG) profile in such a population, and demonstrated the persistence of this pattern at one and six month follow-up evaluations. This profile is characterized by significant deficits of absolute and relative delta and theta power, and excess of relative alpha power, as compared with age expected normal values. Abnormalities were greater in anterior than posterior regions, and disturbances in interhemispheric relationships were also observed. In the current study, 35 adult males with DSM-III-R cocaine dependence, were evaluated while residents of a drug-free residential therapeutic community, 5–15 days after last use of crack cocaine. Using multivariate cluster analysis, two neurophysiological subtypes were identified from the baseline QEEGs; Cluster 1 characterized by significant deficits of delta and theta activity, significant excess of alpha activity and more normal amounts of beta activity (αCLUS) and Cluster 2 characterized by deficits of delta, more normal amounts of theta and anterior excess of alpha and beta activity βCLUS). No significant relationships were found between QEEG subtype membership and length of exposure to cocaine, time since last use of cocaine or any demographic characteristics. Further, no significant relationships were found between the commonly reported comorbid clinical features of depression and anxiety and subtype membership. However, a significant relationship was found between QEEG subtype membership and length of stay in treatment, with members of the αCLUS retained in treatment significantly longer than members of the βCLUS.

Quantitative electroencephalographic profiles of children with attention deficit disorder

Quantitative electroencephalogram (QEEG) was obtained from 407 children with attention deficit disorder. These QEEGs were compared to those of 310 normal children. Discriminant analysis resulted in a specificity of 88% and a sensitivity of 93.7% for distinguishing normal children from those with attention deficit disorder. Two major neurophysiological subtypes were evident within the 92.6% abnormal QEEG profiles encountered. The first showed varying degrees of EEG slowing, especially in frontal regions, whereas the second showed an increase in EEG activity, especially in frontal regions. Deviations from normal development rather than maturational lag were present as the source of the neurophysiological abnormality in the majority of these children. In conjunction with recent magnetic resonance imaging, positron emission tomography, and regional cerebral blood flow studies, these results indicate neurophysiological dysfunction within the cortical and subcortical structures that serve the frontal/striatal system. Models suggesting both hypo- or hyperarousal of these structures are supported.