Psychophysiological evidence of ‘psychoticism’ in schizophrenics' relatives

Abstract

In a series of previous experiments in our laboratory we have demonstrated that a disproportionate number of schizophrenics and others high in ‘psychoticism’ display an unusual psychophysiological profile, charcterized by hightened perceptual sensitivity associated with very low electrodermal activity. the same feature was observed here in a group of adult first-degree relatives of schizophrenics. Compared with a sample of neurotics' relatives, the group contained a significantly greater number of individuals with low-skin-conductance levels (SCL) and high positive slopes relating amplitude and stimulus intensity on a visual evoked potential measure of ‘augmenting-reducing’. A parallel was noted between this observation and a finding, reported earlier on the same sample, that the schizophrenics' relatives also tended significantly more often to show low SCL and high forearm EMG levels. Few relatives showed both anomalous patterns of psychophysiological response, but those who did also had somewhat higher scores on certain questionnaire measures of psychotic personality traits. The results were taken as further evidence for the view that a crucial feature of the biological basis of ‘psychoticism’ may be weakening of CNS homeostasis, possibly implicating cortical regulation of subcortical arousal mechanisms.