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28-02-2011 | Mental health | Article

mfVEPs abnormal in schizophrenia patients

Abstract

Free abstract

MedWire News: The latency of multifocal visual-evoked potentials (mfVEPs) is prolonged and amplitude reduced in patients with schizophrenia relative to mentally healthy individuals, research shows.

"The VEP represents the overall changes in the potential of the visual pathway from retinal photoreceptors to the occipital visual area," observe Eiichi Yukawa (Nara Medical University, Japan) and team.

They explain that "the standard VEP mainly represents macular responses, whereas mfVEPs can be simultaneously extracted as responses of the retinal centre over the about 20° peripheral retina."

However, although previous research has indicated that standard VEP is abnormal in schizophrenia patients, less is known about mfVEPs.

To investigate further, the team recruited 31 antipsychotic-treated patients with schizophrenia, aged a mean of 45 years, and 30 age-matched mentally healthy individuals.

Of note, none of the participants had ophthalmological disease, and all had ophthalmologist-confirmed visual acuity at 20/20 or higher and normal visual field.

All of the participants underwent assessment of mfVEPs, and responses were measured in four quadrants - superior and inferior temporal and nasal quadrants. In each quadrant, two response waves were grouped and averaged, and the latency and amplitude of main waveforms near 100 ms were evaluated.

The researchers found that, overall, peak latency was prolonged by 7 and 9 ms and amplitude was reduced by 2 and 5 nV/deg2 in the upper and lower visual fields, respectively, in schizophrenic patients compared with controls.

The between-group differences were significant in all quadrants, the researchers note in the journal Acta Neuropsychiatrica.

Yukawa and team conclude: "In schizophrenic patients under treatment with psychotropic agents, prolongation of the latency and amplitude reduction were noted in mfVEPs even though no abnormality was detected on the conventional perimetry."

They add: "It is necessary to confirm mfVEP waveforms in schizophrenic patients in the absence of treatment to investigate the degree of influence of psychotropics on the mfVEP waveforms."

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Mark Cowen

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