Objective: Prepulse inhibition (PPI) of the startle reflex deficit and neurological soft signs (NSS) are two markers of vulnerability to psychosis. This study investigated the possibility of a PPI-NSS relation due to a putative common biological substrate, hypothesizing that patients with higher NSS scores also show higher PPI deficits. Moreover, we examined the possibility of an association of PPI deficits and NSS with negative symptoms.
Methods: Fifteen subjects with psychosis and fifteen healthy controls underwent PPI and NSS evaluations.
Results: Patients did not exhibit higher PPI deficits but only higher NSS rates (p < 0.01), as compared with healthy controls. Higher NSS rates were not associated with PPI deficits, and NSS sensory integration signs correlated positively with negative symptoms (p < 0.01).
Conclusion: Our study supported the hypothesis that NSS are trait markers whereas PPI deficits state markers and that their putative common biological substrate is not sufficient to determinate an association between them. The study hypothesis, however, needs further investigation.
Keywords: NSS; PPI; motor sequencing signs; schizophrenia; sensory integration signs.