Diagnostic specificity and predictors of neurological soft signs in schizophrenia, bipolar disorder and other psychoses over the first 4 years of illness.

BACKGROUND: Neurological soft signs (NSS) are well described among patients with schizophrenia, the neurology of other psychoses is relatively unexplored and few comparative studies have prospectively examined these signs in first-episode patients.
METHODS: We assessed neurological functioning in 242 patients presenting with a first episode of psychosis (in accordance with DSM-IV diagnosis) using the Condensed Neurological Examination (CNE). We sought to determine whether NSS were specific to patients with schizophrenia, bipolar affective disorder and other forms of psychosis. We also examined the factors associated with and predictive of neurodysfunction at first presentation and at 4 year follow-up.
RESULTS: NSS were not specific to any diagnostic group. Neurological functioning was closely associated with psychopathology and mixed-handedness at first presentation. At follow-up there was a statistically significant improvement in neurological functioning. Persistent neurodysfunction at this stage was related to enduring negative symptoms and associated with poorer outcome. DISCUSSION: Schizophrenia and bipolar disorder are indistinguishable in terms of neurodysfunction at presentation. At presentation and 4 years NSS closely parallel psychopathology and mixed-handedness indicating that NSS may be a function of these factors or possibly an independent factor operates equally upon both symptoms and neurological function.