In this study strong evidence was found for the unidimensionality of the negative symptoms of schizophrenia. Forty-six schizophrenic patients were rated on the negative subscale of the Positive And Negative Syndrome Scale (PANSS), after which a factor analysis was executed. All items, except one, loaded on one factor, viz. Negative Symptoms.

The patients were also examined on intelligence and some neuropsychological measures. The correlations between these measures and the six negative symptoms were all alike. This was further evidence for the unidimensionality of the negative symptoms. It became clear that negative symptoms go together with visual-practical and frontal lobe dysfunctions (in particular mental inflexibility). The strong associations between negative symptoms and neuropsychological dysfunctions offer the challenging possibility to reduce the negative symptoms by a neuropsychological rehabilitation program.