Comparative effects of schizophrenia and temporal lobe epilepsy on memory.

The goal of this study was to further characterize episodic memory functioning in schizophrenia. This study compared verbal and visual learning and memory performance in (1) patients with schizophrenia (N = 35), (2) patients with temporal lobe epilepsy (TLE; N = 30), and (3) normal controls (N = 25). Results indicated significant memory impairments in patients with schizophrenia and TLE. "Savings" score measures of memory decay showed that the loss of information in schizophrenia and TLE was approximately equal, and quantitatively mild compared to that found in most neurologic groups with memory disorders. The severe difficulty shown by the schizophrenia group on a task of incidental recall suggested that the absence of instructional set added to a vulnerability to memory deficit. In contrast, relatively mildly impaired performance on paired associate learning suggested that patients with schizophrenia benefited from retrieval cues, multiple trials, and short (nonsupraspan) informational loads. Because patients with schizophrenia consisted of a relatively nonchronic sample with a mean IQ of 99.7, their memory disorder could not be attributed to schizophrenic dementia, nor was it accounted for by other potential confounds. Patients with schizophrenia, even those relatively early in the course of illness, have a mild episodic memory disorder.