Hospitalization and the cognitive deficits of schizophrenia. The influences of age and education

Longitudinal Study of Cognitive Variables in Women with Schizophrenia: 31-Year Follow-Up Study

Objective: To longitudinally analyze the course of cognitive dimensions in schizophrenic women over a period of 31 years. Method: Accidental sampling. Developmental longitudinal design. Diagnosis according to the ICD-10. Thirty institutionalized women were evaluated using the WAIS on three separate occasions (in 1981, 1997, and 2012). The data were analyzed using a repeated measures split-plot method. Results: Patients scored one to two standard deviations below the average on the WAIS. At all three evaluation times, they scored consistently, significantly worse on Performance IQ scales than on Verbal IQ in the following sequence: Processing Speed (PS) < Perceptual Organization (PO) < Working Memory (WM) < Verbal Comprehension (VC). Longitudinally, there was a significant, linear average trend that was stable between the first and second assessments, with a significant drop in scores at the third evaluation on Performance IQ (η2 = .586) and Verbal IQ scales (η2 = .299). The same trend was observed in PS (η2 = .655) and WM (η2 = .438), while PO decreased across the three evaluations (η2 = .509) and no difference in VC was found (η2 = .126). Conclusion: Patients with schizophrenia presented with a low cognitive level. Longitudinally, they had a stable, differential profile of WAIS factors until late life, when performance dropped significantly.

WAIS-IV Profile of Cognition in Schizophrenia

The Wechsler Adult Intelligence Scale (WAIS) has been used extensively to study impairment across a range of cognitive domains in schizophrenia. However, cognitive performance among those with the illness has yet to be examined using the newest edition of this measure. Hence, the current study aims first, to provide WAIS-IV normative data for Canadian individuals with schizophrenia of low average intelligence; second, to examine schizophrenia performance on all WAIS-IV subtest, index and general intelligence scores relative to healthy comparison subjects; and third, to revalidate the pattern of impairment identified in this clinical group using the WAIS-III, where processing speed (PS) was most affected, followed by working memory (WM), perceptual reasoning (PR) and verbal comprehension (VC). The WAIS-IV was administered to outpatients with schizophrenia and their performance compared with age, gender, and education matched controls. WAIS-IV schizophrenia performance data are provided. Analyses revealed significant impairment on several tasks, including the new Cancellation subtest and the VC supplemental subtest, Comprehension. At the index score level, group differences in PS were significantly larger than those observed in all other cognitive domains. Impairments were also observed in WM amid relatively preserved performance in VC, thereby confirming the pattern of impairment identified using the WAIS-III.

Schizophrenia--progressive and massive decline in response readiness by episodes

OBJECTIVE

To relate the pattern of neuropsychological impairments among schizophrenic patients to case history data and disease characteristics in a cross-sectional study of unselected patients, and to integrate these data with two previous longitudinal studies of neuropsychological impairments among schizophrenic patients.

METHOD

One hundred consecutive schizophrenic patients were studied with respect to clinical case history and current symptoms, medication and neuropsychological impairment using a comprehensive computerized test battery.

RESULTS

The most salient finding was a marked slowing of response readiness, linearly related to the number of previous acute episodes. The resulting deficit was far beyond what has been obtained in any other group of subjects (average -6 SD for >five episode patients). The impairments in many of the other neuropsychological parameters could to some extent be explained with reference to response slowing, with one exception--verbal short-term memory. Adjustment for important confounding factors (age, duration of illness, medication) did not change the strong negative association between response readiness and number of previous episodes.

CONCLUSION

These findings, together with findings of our two previous longitudinal studies and a recent replication, prompted us to suggest that each acute schizophrenic episode inflicts damage to a set of hypothetical structures, cognitive pattern generators. We assume that these structures translate intentions to logistic programs. When damaged, delays are introduced into executive functions and corollary discharge processes will run out of phase with intentions. This model implicates new ways of looking at the generative mechanisms of the illness, and on treatment strategies.

Is it time to develop a new cognitive therapy for psychosis--cognitive remediation therapy (CRT)?

The cognitive difficulties associated with the disorder of schizophrenia seem to be predictive of future dependence on psychiatric services and predict social functioning. Cognitive remediation therapy (CRT) was designed to rehabilitate these cognitive functions, and the interest in it has grown dramatically over the past ten years. However, the programmes are rarely based on clear theoretical principles and sometimes rely heavily on practice rather than guided learning. The evidence for their efficacy is variable and seems to be dependent on the use of specific components of training. The current review tries to put this evidence into context and sets out a programme of research, which is essential in this area if future progress is to be made.

Confirmatory factor analysis of the WAIS-R in patients with schizophrenia

Although factor scores are commonly used to interpret the Weschsler Adult Intelligence Scale--Revised (WAIS-R), the WAIS-R factor structure has not been investigated in patients with schizophrenia. We used confirmatory factor analysis (CFA) to examine five latent construct models in 169 males with schizophrenia. The WAIS-R standardization sample (ages 35-44; n = 250) was used as a comparison group. For both groups, all model fit indexes used to determine model adequacy supported models composed of Verbal Comprehension (VC), Perceptual Organization (PO) and Freedom from Distractibility (FFD) factors. However, the Digit Symbol subtest loaded on both the PO and FFD factors for patients with schizophrenia but only on the FFD factor for the WAIS-R standardization sample. Patients with schizophrenia performed significantly worse on the FFD and PO factors compared to the VC factor, reflecting the well-characterized attention and problem solving deficits associated with schizophrenia. Also, patients with schizophrenia performed significantly worse than the WAIS-R sample on all factors. These results provide support for the validity of the WAIS-R factors in patients with schizophrenia.

Premorbid educational attainment in schizophrenia: association with symptoms, functioning, and neurobehavioral measures

BACKGROUND

The purpose of this study was to examine the association of educational attainment with phenomenology and neurobehavioral measures assessing brain structure and function in schizophrenia.

METHODS

One hundred sixty-two patients with schizophrenia were divided into two groups on the basis of educational attainment: > or = 13 years of education was the cutoff between the high and low groups. The two education groups were compared on symptomatology, functioning, and subsamples on neuropsychological profile, brain volume by magnetic resonance imaging, and brain metabolism by fluorodeoxyglucose positron-emission tomography.

RESULTS

The patients with more education had lower levels of psychotic symptomatology than their counterparts with less education. This was most evident for affective flattening, alogia, avolition, and bizarre behavior. The higher education group also had better ratings on premorbid adjustment, and the engagement and vocational factors of the Quality of Life Scale. Patients in the high education group also performed better on the neuropsychological battery. There were no brain volume differences or differences in brain metabolism between the two education groups.

CONCLUSIONS

Education is an important indicator of premorbid function and is related to the clinical presentation of schizophrenia.

Executive (frontal) dysfunction and negative symptoms in schizophrenia: apparent gender differences in 'static' v. 'progressive' profiles

BACKGROUND

While executive (frontal lobe) dysfunction appears to be a core feature of schizophrenia, its relationship to psychopathology, age and duration of illness has yet to be explored systematically between the genders.

METHOD

Executive dysfunction, positive and negative symptoms were evaluated in 27 male and 21 female in-patients who were unusually well-matched on numerous demographic and clinical measures.

RESULTS

Measures of executive dyscontrol and negative symptoms were highly associated in both genders. However, while both executive dyscontrol and negative symptoms increased prominently with age/ duration of illness among women, no such relationship was evident among men.

CONCLUSIONS

The similarly prominent levels of current executive dyscontrol and negative symptoms in male and female patients appear to have emerged via processes that differ fundamentally between the genders; among males these deficits appear to emerge and become 'locked in' earlier in the course of illness and to show little subsequent increase, while among females these same deficits appear to be less evident early in the course but to increase in prominence thereafter.

Language processing and memory in ill and well siblings from multiplex families affected with schizophrenia

The present study was designed to extend the investigation of genetic factors for schizophrenia to cognitive and linguistic signs of central nervous system dysfunction. Of 51 siblings studied from 19 schizophrenia multiplex families, 37 had a DSM-III-R diagnosis of schizophrenia or related schzophrenia spectrum disorder and 14 were well. Controls were 17 unrelated healthy individuals within the same social class and age range. Subjects were tested on measures of memory, attention, reading and expressive language ability. Schizophrenic and spectrum disorder siblings were significantly more impaired in tests of auditory discrimination and memory than their well siblings or controls and displayed significantly reduced syntactic complexity to their speech. While well siblings did not differ from controls on most measures, some aspects of language complexity were reduced. A familial effect was observed for tests of reading ability, attention, some syntactic measures, and short-term memory, although these were not the measures that distinguished patients from controls in this cohort, the scores were not correlated among the ill sibling pairs, and poorer scores did not segregate with schizophrenia within these families. Thus, while some measures of language, memory and attention are deviant in patients with schizophrenia, they may not be heritable and directly related to the genetics of the disorder. Instead, they may be a manifestation of, rather than a vulnerability to, the illness.

Influences on cognitive heterogeneity in schizophrenia

A study was conducted of diagnostic reliability, clinical, demographic, iatrogenic, and neurological comorbidity influences on heterogeneity in cognitive function among schizophrenic patients. Comparisons were made between a previously described (Goldstein, 1990) retrospective sample of clinically diagnosed schizophrenic patients and a new sample based on a prospective study of patients meeting strict DSM-III-R diagnostic criteria for schizophrenia. A cluster analysis of a brief battery of cognitive tests suggested a four cluster solution in both samples. The cluster pattern was found to be similar in both samples, indicating that diagnostic unreliability is unlikely to be strongly associated with heterogeneity. Age, general intelligence, and education were found to have significant influences on cluster membership, with length of illness and hospitalization having less robust influences. It was concluded that heterogeneity has a relatively mild relationship with the various influences studied, but a great deal of the diversity in level and pattern of cognitive function found among schizophrenic patients is likely to be a function of heterogeneity within the disorder itself.

Low prevalence of age disorientation in Dutch long-stay patients

Studies in Great-Britain and the USA have established the prevalence of 'age disorientation', defined as a discrepancy between true and subjective age of five years or more, as approximately 25% in the population of long-stay patients with a diagnosis of schizophrenia. We examined all schizophrenic patients in long-stay wards of three mental hospitals and found a prevalence of 6% (95% CI: 0.9-10.6%). We have no definitive explanation for this finding. 'Age disorientation' may be the result of an interaction between a serious form of the illness and poor psychosocial treatment.

Cortical cholinergic markers in schizophrenia

Cortical cholinergic deficits have been implicated in the cognitive deficits produced by a variety of neurodegenerative diseases including Alzheimer's disease (AD). Recent studies have suggested that many of the chronically institutionalized geriatric schizophrenic patients are also cognitively impaired. In this postmortem study we compared cholinergic marker activity in six different cortical regions derived from elderly controls, chronically institutionalized geriatric schizophrenic patients, and AD patients. All of the Alzheimer's disease cases met neuropathological criteria for AD, while none of the schizophrenic cases met criteria for AD. Cholinergic marker activity (choline acetyltransferase and acetylcholinesterase) was significantly diminished in the AD cohort but not in the schizophrenic cohort. Additionally, cortical choline acetyltransferase activity was significantly and negatively correlated with Clinical Dementia Rating scores (CDR), whereas no such correlations were evident in the schizophrenic cohort. These results suggest that cognitive deficits in geriatric schizophrenics are not due to diminished cortical cholinergic activity.