Sensory Processing Deficits Across Modalities in Schizophrenia

Sherlyn Yeap, RCSI

Abstract
Schizophrenia research has recently focused on the search for endophenotypic or trait markers. In the race to develop a quantifiable, easily measured marker, the use of high density electrical mapping in patients and those at high risk of schizophrenia has played a key role.

Sensory processing deficits in both the visual and auditory modalities have previously been established in patients with chronic schizophrenia. Our study aimed at looking for early visual deficits, in particular the P1, and the auditory MMN (mismatch negativity), in both frequency and duration, in clinically unaffected first-degree relatives and their probands. Of interest also was the degree of correlation between the two modalities in each individual subject.

Twenty-five clinically unaffected first-degree relatives and their 16 probands were recruited. Their results were compared to 26 age-matched controls. Event related potentials revealed early visual processing deficits in the midline dorsal electrodes in the first-degree relatives and proband groups when compared to controls. The effect size was large (d=0.09). The result also supported previous studies showing magnocellular pathway deficits in patients. There was no difference observed in the MMN in the three groups.

Because first-degree relatives share genes with their schizophrenic counterparts, we were confident that the changes observed here in this population would be invaluable as endophenotypes.

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