Objective: Neurological abnormalities in subjects with schizophrenia have been regarded as diagnostically non-specific and non-localising. This study assessed the temporal stability of neurological abnormalities in subjects with first-episode schizophrenia over the course of 12 months. We also examined their relationships with psychiatric symptoms, medication effects and treatment outcome.
Method: The sample comprised 66 largely medication-naive subjects who were treated according to a fixed protocol. We performed a factor analysis of the Neurological Evaluation Scale (NES) items, and relationships between the NES factors and various clinical and outcome measures were explored.
Results: Five NES factors were identified, explaining 68.4% of the variance. While the NES total scores did not change significantly over time, poor performance on motor sequencing tests was related to longer duration of untreated psychosis, and showed a tendency to improve as psychiatric symptoms resolved. The most interesting finding was that high scores on the motor sequencing factor predicted the emergence of persistent dyskinesia at 24 months (ANCOVAR F(1, 20) = 19.287, p = 0.0002).
Conclusions: Two NES factors (motor sequencing and attention) are reasonably replicable across samples, and have potential relevance for the further exploration of the pathogenesis of schizophrenia, as well as possible clinical applications.