Visual sensory processing deficits in Schizophrenia and their relationship to disease state

Abstract

Context Visual Evoked Potential (VEP) abnormalities have been a fairly consistent finding in patients with schizophrenia, and it has been suggested that electrophysiological markers of early sensory processing may be useful as trait markers for the illness, and for development as potential diagnostic measures. Objective Clear amplitude reductions in the occipital P1 component of the VEP (~100 ms), have been repeatedly demonstrated in patients with schizophrenia. Here, we investigated whether the extent of this deficit was related to age, clinical symptoms, medication status and length of illness, in a large cohort of ethnically homogenous patients. Design, setting and participants VEP responses to simple isolated-check stimuli were examined in 52 DSM-IV diagnosed patients with schizophrenia, and compared with responses from 26 healthy age-matched control subjects. Using high-density electrical scalp recordings, we assessed the integrity of the visual P1 component across the two groups. This study was conducted at St.Vincent's Psychiatric Hospital in Fairview, Dublin, Ireland. Results Substantially reduced P1 amplitude was demonstrated in the patient group compared to controls. The deficit was not linked to age, length of illness or medication status. A small positive correlation, accounting for about 11% of the variance, was found between P1 amplitude and clinical symptoms scales (BPRS and SANS). In addition, we found that a slightly later (~110 ms) fronto-central component was relatively increased in the patient group, and was inversely correlated with the occipital P1 amplitude in the patients, but not in the healthy control subjects.Conclusions Our findings clearly demonstrate a deficit in early visual processing in patients with schizophrenia (with a large effect size; Cohen's d = 0.7) that is unrelated to chronicity. The results are consistent with recent findings showing that the P1 deficit is endophenotypic of the disorder and related to genetic risk factors rather than the disease process itself.j Key words visual-evoked potential AE VEP AE ERP AE P1 deficit AE schizophrenia AE Ireland AE hyperfrontality

Effects of Acute Ketamine Infusion on Visual Working Memory: Event-Related Potentials

“…P100 amplitude was greater under ketamine than under placebo, which went against our prediction that the pattern observed in schizophrenia (8,(10)(11)(12)59,63) would be replicated. There are several potential ways to interpret our unexpected finding .…”

“…Koychev et al (13) reported Q3 that P100 amplitude predicted performance during a visual WM task in healthy control subjects but was reduced in patients with early-onset schizophrenia. These P100 effects in patients were demonstrated to be independent of drug dosage or symptom severity (8). Based on these and other data, it has been suggested that cognitive deficits in schizophrenia could involve abnormal sensory (i.e., bottom-up) processing (9).…”

“…Several studies report that patients with schizophrenia have reduced amplitude of early visual evoked response potentials (ERPs) as early as 100 ms after stimulus onset-the P100 potential (8)(9)(10)(11). This may be a trait marker for vulnerability, as it has been reported in unaffected first-degree relatives (12) and high schizotypal individuals (13).…”

Disturbed theta and gamma coupling as a potential mechanism for visuospatial working memory dysfunction in people with schizophrenia

“…PSZ have been found to demonstrate deficits in ERPs elicited from WM tasks [17][18][19] and tasks probing sustained attention [20][21][22][23][24], among others; similar deficits have been observed in first-degree relatives of people with the disorder [22,25,26]. More recently, EEG research has examined oscillatory activity in the brain associated with WM.…”

Psychiatric Disorders And Eye: Optical Coherent Tomography In Psychiatry Aspect

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