Purpose of review
The symptoms of schizophrenia cluster in at least three subtypes: positive, negative, and disorganized. The study of these subtypes and their phenotypic markers may help our understanding of the pathophysiology of schizophrenia. Among the markers of schizophrenia are minor neurological signs, which are abnormalities in sensory and motor performance elicited by clinical examination. Evidence on whether neurological abnormalities are associated with a specific symptom subtype is considered. As recent studies have often evaluated individuals at their first psychotic episode who are antipsychotic naïve, a review would help to clarify whether neurological soft signs are part of a neurodysfunction that underlies schizophrenia rather than the consequence of degenerative processes or of long-term pharmacological treatment.
A consistent association seems to emerge between an excess of neurological soft signs and severe negative symptoms. Signs associated with negative symptoms remain stable over time, and may characterize a subgroup of patients with poor illness course and outcome. Some signs, such as motor dysfunction, may be associated with a worse profile of positive symptoms, and may improve as symptoms improve. Too few studies have evaluated the association between neurological soft signs and disorganization symptoms to suggest or disconfirm any relationship.
Finding an association between neurological soft signs and one (or more) dimension(s) of schizophrenia in never treated patients may explain which neurological dysfunction is an intrinsic characteristic of the illness. The comparability of future studies can be improved by using the same structured rating scale for neurological soft signs and psychopathology, and by a better characterization of patient samples.