Frontal release signs and cognition in people with schizophrenia, their siblings and healthy controls

Background: Frontal release signs, a subset of neurological soft signs, are common in schizophrenia. Aims: To explore the relationship between frontal release signs and neuropsychological tests of frontal lobe function in people with schizophrenia, their siblings and healthy controls. Method: Neuropsychological tests and frontal release signs were measured in a cohort of index cases (n=302), their siblings (n=240) and healthy controls (n=346). Results: The mean total score of frontal release signs was 1.5 (s.d.=1.58) in the schizophrenia group, 0.54 (s.d.=0.92) for siblings and 0.42 (s.d.=0.77) for controls. Schizophrenia group scores were greater than healthy control or sibling cohort scores (P < 0.0001), which did not differ. In all three cohorts, right grasp reflex scores positively correlated with number of perseverative errors on the Wisconsin Card Sort Task (P < 0.05). In the schizophrenia group, frontal release signs scores showed an inverse correlation with IQ (R= -0.199, P < 0.0005). Conclusions: Our findings of relationships between frontal release signs and cognitive assays of cortical dysfunction and the increased frequency of these signs in people with schizophrenia implicate a cortical origin for these clinical signs and evidence of frontal lobe dysfunction in this disorder.