Frontal release signs, a subset of neurological soft signs, are common in schizophrenia.

To explore the relationship between frontal release signs and neuropsychological tests of frontal lobe function in people with schizophrenia, their siblings and healthy controls.

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).

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).

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.

Previous in vivo studies of schizophrenia with dopamine D2 receptor radioligands have yielded contradictory results. No prior study has used multiple scans to examine within-subject clinical change.

Twenty-one patients were studied with [1231]-iodobenzamide single photon emission computed tomography about two weeks after neuroleptic withdrawal. Thirteen of the 21 completed a second scan about four weeks after neuroleptic withdrawal. Sixteen controls were scanned for comparison.

There was no significant difference between groups in [1231]-iodobenzamide uptake at either scanning session. No significant correlations with demographic variables (age, illness duration, drug-free period), or clinical ratings (positive and negative symptoms, movement disorder) were observed at either scanning session. There was a significant correlation between change in [1231]-iodobenzamide uptake and change in negative symptom ratings for the subjects who underwent two scans (r=0.72, P < 0.05)

Worsening of negative symptoms may be associated with increased availability of striatal D2 receptors, perhaps because of decreased concentrations of endogenous dopamine.