Verbal memory deficits have been reported in many studies of patients with schizophrenia. We evaluated the specificity of these deficits by comparing patients and control subjects on several verbal and nonverbal auditory memory tests.
Performance of stable, medicated outpatients with DSM-III-R diagnoses of schizophrenia (N=38) was compared with that of healthy subjects (N=39) on a word list immediate recall task, tone delayed discrimination tasks, and word and tone serial position tasks. Before memory testing, patients were divided into 2 groups based on their ability to perform normally on a screening test requiring pitch discrimination and sustained attention.
The nonverbal tests were more difficult for control subjects than the verbal tests. Despite this, patients who performed normally on the screening test of perception and attention performed normally on both nonverbal tests but had highly significant deficits on both verbal tests (P<.001 and P=.02). Patients who performed poorly on the screening test had highly significant performance deficits on all the memory tests.
One subgroup of patients with schizophrenia has a selective deficit in verbal memory despite normal motivation, attention, and general perceptual function. Another group has deficits in multiple aspects of cognitive function suggestive of failure in early stages of information processing.