Depression, psychomotor retardation, negative symptoms, and memory in schizophrenia.

OBJECTIVE: The purpose of this study was to examine the relations between depression, psychomotor retardation, and negative symptoms in schizophrenia as well as the specific contribution of each of these factors to memory impairment.
BACKGROUND: It has been suggested that depression overlaps with negative symptomatology in schizophrenia. The relation between psychomotor retardation and negative symptomatology has been unclear.
METHOD: The Hamilton Depression Rating Scale, The Positive and Negative Symptom Scale for Schizophrenia, and Scale for the Assessment of Negative Symptoms were used to assess depressive and negative symptomatology in a sample of patients with schizophrenia. Verbal memory performance was assessed by a free recall test. Two indices of processing speed were measured. Correlations among variables were computed.
RESULTS: Depression score was correlated with the avolition item from the Scale for the Assessment of Negative Symptoms and with both measures of processing speed. Negative symptomatology was unrelated to processing speed. Memory performance was correlated with depression score, slowing of processing speed, and avolition. Its correlation with depression score and processing speed remained significant when the other factors were partialled out.
CONCLUSIONS: Memory performance in schizophrenia may be affected by lack of motivation, psychomotor retardation, and depression. It is suggested that negative symptoms could be split between a volitional component linked to depression and cognitive efficiency and an emotional component unrelated to them.