Objective: Patients with schizophrenia are characterized by neurological abnormalities, which can be assessed by bedside clinical examination. These abnormalities have been argued to represent core features of the illness. We review studies published since our last review in 1988 that address the validity of neurological signs as a trait feature of schizophrenia.
Methods: We conducted a literature search in the following computer databases: MEDLINE, PSYCHLIT, EMBASE, and COCHRANE. The search was limited to articles published from January 1988 to May 2005.
Results: Neurological signs occur in the majority of patients with schizophrenia. Their occurrence is independent of demographic and most medication variables. Neurological signs are strongly associated with negative symptoms and cognitive impairments. There is also evidence to suggest that their occurrence is under genetic control.
Conclusions: There is compelling evidence to suggest the hypothesis that neurological signs represent a trait feature of schizophrenia.