Treatment of negative symptoms.

The rational treatment of the negative symptoms of schizophrenia requires a careful differentiation of those secondary to a range of other factors and those that constitute enduring primary or deficit symptoms. Secondary negative symptoms are usually responsive to treatment of the underlying cause. In contrast, there is no intervention currently available with established efficacy in treating deficit symptoms. These distinctions serve to reduce the heterogeneity of negative symptoms. A discussion of the diagnosis and treatment of the various forms of secondary negative symptoms is followed by suggestions for future research in the treatment of deficit symptoms.