N100 and P300 amplitude to Go and No-Go variants of the auditory oddball in siblings discordant for schizophrenia.

BACKGROUND

P300 amplitude reduction is reliably seen in schizophrenia. Inconsistent reports of isolated frontal and/or parietal deficits in unaffected family members may be clarified using a task that places greater load on frontal function.

METHOD

Go and No-Go versions of the auditory oddball task were performed by eighteen schizophrenia patients, age-matched unaffected siblings and healthy controls matched closely to unaffected siblings on age, sex, education, socioeconomic-status, handedness and ethnicity. Groups were compared on P300 and N100 amplitude and latency. Spearman correlations were used to test the relationship between ERP amplitudes and neuropsychological measures of executive function and memory. The relationship between schizotypy--as measured using the structured interview--and ERPs was explored in a combined group of siblings and controls.

RESULTS

Independent of task, patients had lower P300 than controls and reduced parietal amplitude compared to siblings. Siblings had enhanced frontocentral N100 compared to controls. No-Go P300 amplitude and N100 latency was associated with executive function measures. There were significant intraclass correlations between patients and siblings for No-Go P300 amplitude, particularly at the central midline electrode. Frontocentral N100 and P300 amplitude were positively correlated with anxiety-related aspects of schizotypy.

CONCLUSION

Enhanced N100 is present in unaffected siblings. Parietal P300 is intact in unaffected siblings, but reduced in patients. The No-Go-oddball is more sensitive than the Go-oddball to executive function deficits in patients and as an index of heritability.