Performance of chronic schizophrenic patients on cognitive neuropsychological measures sensitive to dementia

Abstract

Although many chronic schizophrenic patients manifest substantial global cognitive impairment, it is not clear as to whether this impairment should be characterized as dementia. Since many degenerative dementias have a characteristic signature of cognitive impairment and a specific pattern of cognitive decline, examination of schizophrenic patients on these measures can provide information about the qualitative similarity of their cognitive impairment to these other conditions. Three hundred and two chronically hospitalized schizophrenic patients ranging in age from 26 to 98 were examined with the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological battery, as well as a more global measure of cognitive impairment, the Mini‐Mental State Examination (MMSE). This assessment was repeated twice, with a 1‐year follow‐up interval. The CERAD battery measures the prototypical cognitive deficits of Alzheimer's disease, including word list learning and delayed recall, naming and praxis. In contrast to Alzheimer's disease, all aspects of cognitive impairment were linearly associated with MMSE scores and there were no qualitatively different patterns of deficits associated with MMSE scores in different ranges of severity. There was no change in performance on any measure across the follow‐up period, regardless of the MMSE scores of the patients at baseline. These data suggest that the specific patterns of deficit in chronic schizophrenic patients with severe cognitive deficits differ from Alzheimer's disease in both course and profile of impairment.

Accelerated age-related decline in processing resources in schizophrenia: Evidence from pupillary responses recorded during the span of apprehension task

“…Moreover, the age-related increase in P300 latency in the patients with schizophrenia was significantly greater than in age-comparable controls. The findings from this study by O'Donnell et al (1995) are consistent with the findings from the present study and several previous studies reviewed above (Bilder et al, 1992;Harvey et al, 1995aHarvey et al, , 1995bHarvey et al, , 1996Waddington & Youseff, 1996) that suggest a neurodegenerative process in schizophrenia.…”

“…Bilder et al (1992) used intelligence test profiles to estimate the difference between premorbid and current cognitive functioning in patients with schizophrenia and found that deterioration may follow the onset of psychosis in subgroups of patients. Harvey et al (1995aHarvey et al ( , 1995bHarvey et al ( , 1996 also found significant age-related decline on gross cognitive screening measures in large samples of chronically institutionalized older patients with schizophrenia, suggesting a possible neurodegenerative process. Waddington and Youseff (1996) also found progressive cognitive decline over a 10-year follow-up in chronic inpatients with schizophrenia.…”

“…In contrast, neuropsychological deficits found in older outpatients with schizophrenia appear quantitatively and qualitatively different from those found in dementia of the Alzheimer's type (Granholm & Jeste, 1994;Harvey et al, 1996;Heaton et al, 1994), suggesting clear differences between schizophrenia and progressive cortical dementia. Heaton et al (1994) found that age-corrected impairment scores from a large neuropsychological test battery did not differ significantly between large cohorts of younger and older patients with schizophrenia, suggesting normal agerelated cognitive decline in schizophrenia.…”

Age-related differences in formal thought disorder in chronically hospitalized schizophrenic patients: a cross-sectional study across nine decades

“…It is not clear if the lower Mini-Mental State scores in geriatric patients with poverty of speech were due to schizophrenia or some type of additional condition that induced dementia. Our previous research on cognitively impaired geriatric schizophrenic inpatients has indicated that the pattern of cognitive impairment (22) and postmortem neuropathology (24,25) is different from that seen in degenerative dementing conditions such as Alzheimer's disease. Our most recent research (26) has suggested that even when additional neuropathological causes of dementia are examined postmortem (e.g., vascular dementia, Lewy body dementia, Creutzfeldt-Jakob syndrome), over 75% of cognitively impaired schizophrenic patients have no identifiable neuropathology to explain their cognitive status, which suggests that this cognitive impairment may be an intrinsic feature of a large number of patients with chronically unremitting schizophrenia.…”

Cognitive impairment in elderly patients with schizophrenia: age related changes

“…In two different studies of the same sample of patients, Harvey et al (1995) found that, as a group, there was no decline in MMSE scores over a two-year follow-up of 50 elderly patients with schizophrenia. Using a cognitive battery sensitive to the typical cognitive de®cits in AD, Harvey et al (1996) found no signi®cant change over a one-year follow-up period. In contrast, previous studies of patients with AD have revealed statistically signi®cant cognitive declines during the same one-year time frame (Welsh et al, 1991).…”