OBJECTIVE: Both neuropsychological impairment and neurological soft
signs have been documented in at least a subset of patients with
schizophrenia. The purpose of the present study was to examine the
relationship between soft signs and neuropsychological performance in
patients with schizophrenia in order to address the issue of whether soft
signs are related to global or more selective cognitive impairment. METHOD:
Patients with a DSM-III-R diagnosis of schizophrenia (N=176) were given a
standardized neuropsychological battery and underwent a neurological
examination. The study group was dichotomized on the basis of presence or
absence of neurological soft signs. RESULTS: Patients with neurological
soft signs (N=68) demonstrated significantly poorer performance on
neuropsychological tasks that assessed timed motor speed and motor
coordination (e.g., finger tapping, the Purdue Pegboard task, and part B of
the Trail Making Test). These findings continued to be significant even
after lifetime medication exposure, extrapyramidal symptoms, and abnormal
involuntary movements were used as covariates. CONCLUSIONS: These findings
support the notion that soft signs are a manifestation of a localizable
behavioral deficit of the systems that are involved in motor speed,
coordination, and sequencing and are not indicative of global cognitive
impairment. The specific deficit in motor abilities is consistent with the
types of neurological soft signs that are most frequently reported and
suggests involvement of frontal/subcortical circuitry in schizophrenia.Abstract Teaser