Habituation and prepulse inhibition of the acoustic startle reflex: Effects of smoking status and psychosis-proneness

The influence of smoking status and psychosis-proneness as assessed by the Psychoticism (P) scales of the Eysenck Personality Questionnaire (EPQ) and the Eysenck Personality Questionnaire-Revised (EPQ-Revised) on habituation and prepulse inhibition (PPI) of the acoustic startle reflex were investigated in a non-clinical population of 56 healthy men. Non-smokers who scored high (> median) on the EPQ P scale showed less habituation of the startle reflex over pulse-alone trials and shorter latencies to response onset for the pulse-alone as well as prepulse trials than low scoring (< median) non-smokers. There was a trend for reduced PPI of the startle reflex in high EPQ P as compared with low EPQ P non-smokers; PPI by prepulses with 60-msec and 120-msec lead intervals, was significantly negatively correlated with the EPQ P scores in non-smokers. No significant influence of the EPQ P scores was observed in smokers on any of the startle measures. The EPQ P (1975) and EPQ-Revised P (1985) scales were highly positively correlated (r = 0.86), but the EPQ-Revised P scores were not significantly related to either habituation or PPI of the startle reflex, though (non-significant) effects were in the same direction as found for the EPQ P scores. These findings extend earlier reported findings of impaired habituation of the startle reflex in schizophrenic patients to individuals scoring high on psychoticism (EPQ, 1975), and provide support for the hypothesized link between psychoticism and schizophrenia. The findings also suggest that cigarette smoking may to some extent normalize habituation and PPI of the acoustic startle reflex in schizophrenia related populations.