Negative symptoms in schizophrenia and nailfold plexus visibility

Visibility of the nailfold vascular plexus has shown promise as a genetically transmitted marker for liability to schizophrenia. To assess whether this marker is specifically associated with negative or positive symptoms of schizophrenia, we reanalyzed patient data collected 20 years ago, well before interest in the negative/positive symptom distinction. Eighty-four patients, who retrospectively met DSM-III-R criteria for schizophrenia, had been rated for plexus visualization score (PVS) and independently interviewed using the Mental Status Schedule (MSS). Content scales were derived from the MSS to assess negative, positive, and affective symptoms. There was a highly significant correlation between PVS and negative symptoms (including verbal, motor, cognitive and motivational deficits), but not between PVS and positive or affective symptoms. These findings indicate that the negative symptoms of schizophrenia are due to a disease process biologically distinguishable from those causing positive symptoms and that plexus visibility is a risk marker for this pathology.