Topographic abnormalities of P3 in schizotypal personality disorder
ABSTRACT Schizotypy, a schizophrenia spectrum disorder, is of interest because schizotypes share traits with schizophrenics, albeit milder, without potential confounds such as chronic neuroleptic treatment and/or hospitalization. Thus, schizotypy may be particularly useful in exploring biological correlates of an underlying schizophrenic predisposition. The P3 event-related potential, which is aberrant in schizophrenia, was measured in 11 male, right-handed, DSM-III-R-defined schizotypes and 11 matched controls while subjects covertly counted 1.5 kHz target tones (15%) in trains of 1 kHz standard tones. Like schizophrenics, schizotypes displayed an asymmetrical P3, with smaller amplitudes over the left temporal lobe. Unlike schizophrenics, schizotypes were not significantly smaller in P3 amplitude over the sagittal midline of the head, although there was a trend towards reduced amplitudes at central and posterior midline sites. Asymmetry of P3 amplitude, with left-sided deficit, may be associated with the schizophrenia diathesis, but overall P3 reductions may be more associated with chronic effects.
SourceAvailable from: Gráinne McLoughlin[Show abstract] [Hide abstract]
ABSTRACT: Current clinical parameters used for diagnosis and phenotypic definitions of psychopathology are both highly variable and subjective. Intensive research efforts for specific and sensitive biological markers, or biomarkers, for psychopathology as objective alternatives to the current paradigm are ongoing. While biomarker research in psychiatry has focused largely on functional neuroimaging methods for identifying the neural functions that associate with psychopathology, scalp electroencephalography (EEG) has been viewed, historically, as offering little specific brain source information, as scalp appearance is only loosely correlated to its brain source dynamics. However, ongoing advances in signal processing of EEG data can now deliver functional EEG brain-imaging with distinctly improved spatial, as well as fine temporal, resolution. One computational approach proving particularly useful for EEG cortical brain imaging is independent component analysis (ICA). ICA decomposition can be used to identify distinct cortical source activities that are sensitive and specific to the pathophysiology of psychiatric disorders. Given its practical research advantages, relatively low cost, and ease of use, EEG-imaging is now both feasible and attractive, in particular for studies involving the large samples required by genetically informative designs to characterize causal pathways to psychopathology. The completely non-invasive nature of EEG data acquisition, coupled with ongoing advances in dry, wireless, and wearable EEG technology, makes EEG-imaging increasingly attractive and appropriate for psychiatric research, including the study of developmentally young samples. Applied to large genetically and developmentally informative samples, EEG imaging can advance the search for robust diagnostic biomarkers and phenotypes in psychiatry. © 2013 Wiley Periodicals, Inc.American Journal of Medical Genetics Part B Neuropsychiatric Genetics 03/2014; DOI:10.1002/ajmg.b.32208 · 3.27 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: The present study investigated the relationships among event-related potentials (ERPs), memory, and schizophrenic symptoms in college students with schizotypal-traits. Scores on the Schizotypal Personality Questionnaire (SPQ) were used to categorize the participants into schizotypal-trait (n = 30) and normal control (n = 37) groups. ERPs were assessed using an auditory oddball paradigm, in which a series of standard tones (1000 Hz) and target tones (1500 Hz) were presented; partici-pants were asked to count the number of presented target tones. The verbal memory and visual memory of the participants were evaluated using the Korean version of the California Verbal Learning Test (K-CVLT) and the Rey-Osterrieth Complex Figure Test (RCFT), respectively. The schizotypal-trait and control groups did not differ in terms of age, educational level, IQ score, ac-curacy on the auditory oddball task, or performance on the K-CVLT and RCFT measures. However, the schizotypal-trait group exhibited significantly smaller P300 amplitudes than the control group. Additionally, the P300 amplitudes measured at Cz and Pz were negatively correlated with the cog-nitive-perceptual factor scores on the SPQ. Thus, the present results indicate that reduced P300 amplitudes may represent a biological marker of schizophrenia.Open Journal of Psychiatry 10/2014; 4(4):353-363. DOI:10.4236/ojpsych.2014.44041
[Show abstract] [Hide abstract]
ABSTRACT: Electrophysiological indices are sensitive to cognitive dysfunction in schizophrenia but have rarely been used to assess benefits of cognitive remediation. Our aim was to evaluate the effect of specific cognitive training approaches on event-related potentials. Forty-six patients with schizophrenia underwent either auditory (AUD) or visuo-spatial (VIS) cognitive training or treatment-as-usual (TAU). Cognitive training was computer-assisted and administered for 10 sessions within two weeks. Event-related potentials during an active odd-ball paradigm together with clinical and neuropsychological variables were assessed before and after training and again at a two-month follow-up. Compared to the TAU group both the AUD and VIS training group showed decreased P2 latency following training. At follow-up, the P2-latency reduction was stable in the VIS group but the AUD group experienced a relapse. Training resulted in improved digit-span backward among neuropsychological variables. Increased P2 amplitude was related to more positive symptoms and lower social-occupational functioning and longer P2 latency was associated with greater severity of stereotyped thinking. The more general visuo-spatial training appears to have a longer-lasting effect on P2 latency than the specific auditory training. Alternatively, there may be specific auditory discrimination deficits in schizophrenia requiring more extensive training for a stable change.10/2014; 1(4):180-186. DOI:10.1016/j.scog.2014.07.001