[The deficit syndrome: a domain of schizophrenia].

Schizophrenia is a heterogeneous clinical syndrome and this variability may reflect differences in etiology and pathophysiology. Such heterogeneity could be responsible for the difficulties in research when all patients with schizophrenia are included in the same group. Subgroups of more clinical homogeneity are more likely to be homogeneous for the presumed pathophysiology of interest. Primary, enduring negative symptoms have been proposed to designate the deficit syndrome. The data obtained in the recent years and summarized in this review show that negative symptoms broadly defined are less effective for subgrouping schizophrenia and that the deficit syndrome is a different domain within schizophrenia.