Ashley A. Miles

Are schizophrenia and schizoaffective disorder neuropsychologically distinguishable

This study sought to objectify the distinction between schizophrenia and schizoaffective disorder in terms of standard tasks measuring verbal and non-verbal cognitive ability, auditory working memory, verbal declarative memory and visual processing speed. Research participants included 103 outpatients with a diagnosis of schizophrenia, 48 with schizoaffective disorder, and 72 non-patients from the community. Schizophrenia patients were impaired on all cognitive measures relative to schizoaffective patients and non-psychiatric participants. Regression-based prediction models revealed that cognitive measures classified schizophrenia patients accurately (91%), but not patients with schizoaffective disorder (35%). In addition, there was no statistical evidence for the unique predictive validity of any specific cognitive task. Patients with schizophrenia were significantly more symptomatic and had greater community support requirements than those with schizoaffective disorder. However, group differences in cognitive performance are insufficient to separate these syndromes of psychotic illness.

Predictors of medication competence in schizophrenia patients

Competence in self-administration of a drug regimen is related to both treatment adherence and functional outcome. Previous research with middle-aged and older schizophrenia patients suggests a central role for cognitive performance in predicting this competence. We examined the relative and joint contributions of demographic, clinical and cognitive predictors of medication management ability in an age-representative group of patients. The study participants comprised 147 patients with schizophrenia or schizoaffective disorder ranging from 21 to 65 years of age. Measures included demographic variables, current symptoms, subjective treatment response and a battery of cognitive tests. Competence in medication management was indexed with the Medication Management Ability Assessment (MMAA). Multiple regression analyses revealed that cognitive variables accounted for a significant proportion of the variance in MMAA scores over and above the contribution of all other variables. Measures of word recognition and pronunciation, auditory working memory and verbal learning yielded unique contributions to prediction. Positive and negative symptoms and subject treatment evaluations did not independently predict medication competency. This study documents a considerable range in MMAA scores across a demographically broad schizophrenia sample and supports the unique contribution of specific cognitive factors in predicting medication competence.

Cognitive Performance and Functional Competence as Predictors of Community Independence in Schizophrenia

Measures of functional competence have been introduced to supplement standard cognitive and neuropsychological evaluations in schizophrenia research and practice. Functional competence comprises skills and abilities that are more relevant to daily life and community adjustment. However, it is unclear whether relevance translates into significantly enhanced prediction of real-world outcomes. The aim of this study was to assess the specific contribution of functional competence in predicting a key aspect of real-world outcome in schizophrenia: community independence. Demographic, clinical, cognitive, and functional competence data were obtained from 127 patients with schizophrenia or schizoaffective disorder and used to predict community independence concurrently and longitudinally after 10 months. Hierarchical regression analyses indicated that demographic, clinical, and cognitive predictors accounted jointly for 35%-38% of the variance in community independence across assessment points. Functional competence data failed to add significantly to this validity. Considered separately from demographic and clinical predictors, cognitive and functional competence data accounted for significant amounts of outcome variance. However, the addition of functional competence to standard cognitive test data yielded a significant increase in validity only for concurrent and not for longitudinal prediction of community independence. The specific real-world validity of functional competence is modest, yielding information that is largely redundant with standard cognitive performance.

Psychopathology and cognition in divergent functional outcomes in schizophrenia

Cognitive performance rather than symptoms, especially positive symptoms, is regarded as the primary predictor of functional outcome in schizophrenia. However, contradictory evidence exists and many studies fail to sample from the extremes of outcome measures. This study tested whether the differential importance assigned to symptoms and cognitive impairment is supportable in patients with high and low levels of community independence. Schizophrenia patients with highly unfavorable (n=24) and highly favorable (n=28) functional outcomes as defined by community support requirements were studied. Standard cognitive and psychopathology measures were analyzed using independent groups comparisons and outcome prediction with logistic regression methods. Symptom severity and cognitive data separately accounted for significant amounts of variance in community independence. Positive as well as negative symptoms, non-psychotic psychopathology and cognition generated large effect sizes between highly unfavorable and favorable outcome groups. The conditional validity of both overall psychopathology and positive symptoms was significant over and above the contribution of cognition to outcome prediction. Results suggest researchers may have underestimated the role of psychopathology in general and positive symptoms in particular as potential determinants of functional status in schizophrenia.

An investigation of 3 neurocognitive subtypes in schizophrenia

The purpose of this investigation was to identify patients with cognitively impaired, cognitively normal and verbal memory-impaired subtypes of schizophrenia and to examine their clinical and functional validity as distinct forms of the disorder. These subtypes occurred in 73 of 154 patients meeting DSM-IV criteria for schizophrenia or schizoaffective disorder. A control group comprised of 18 healthy participants was also analyzed. Patient subtype and healthy groups were compared on adjunct cognitive as well as clinical and functional measures. The data support the cognitive validity and differentiation of these subtypes, with evidence that the generalized cognitive normality/impairment distinction associates with important aspects of symptom severity and functional outcome. Support for the clinical and functional validity of the verbal memory subtype was more equivocal. Overall, cognitively-based subtyping merits additional attention in efforts to organize the heterogeneity of the schizophrenia syndrome.

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.

Stability and change in symptoms, cognition, and community outcome in schizophrenia

It has been well established that neurocognitive deficits are a core feature in schizophrenia and predict difficulties in functional independence. However, few studies have assessed the longitudinal stability of cognition and key aspects of functional outcome concurrently. Even less attention has been directed at the contingency of cognitive change on real world outcome changes. Accordingly, this study will assess the extent to which significant changes in cognition and community status are independent or related. As a point of comparison, the stability of clinical symptom status and the relationship between symptom and outcome change are evaluated. Symptoms, cognitive abilities, and community outcome was assessed in 128 patients with schizophrenia at baseline and again one year later. Intraclass correlation coefficients were used to index stability and reliable change index analyses quantified the prevalence of significant improvement or deterioration in each of the three illness features. Results from these analyses revealed that symptom status, cognitive functioning, and community outcome are similarly stable in treated schizophrenia outpatients. A small proportion of the sample demonstrated significant improvement or deterioration in these domains, with only weak evidence that such change was predicted by changes in symptoms or cognition. Further, there was no strong evidence of a preferential relationship for cognition relative to symptoms in relation to functional outcome. These results shed light on the strength and nature of the cognition-real world outcome relationship in schizophrenia and have implications for pharmacological and behavioral interventions aimed at improving real world outcome.

Community Outcome in Cognitively Normal Schizophrenia Patients

Recent reports suggest that cognition is relatively preserved in some schizophrenia patients. However, little is known about the functional advantage these patients may demonstrate. The purpose of this study was to identify cognitively normal patients with a recently developed test battery and to determine the functional benefit of this normality relative to cognitively impaired patients. Average-range cognitive ability was defined by the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) composite score (T≥40) and applied to 100 patients with schizophrenia or schizoaffective disorder and to 81 non-psychiatric research participants. With group assignment adjusted for demographic variables, this procedure yielded 14 cognitively normal patients, 21 cognitively impaired patients, and 21 healthy adults with normal-range MCCB scores. Cognitively normal patients were indistinguishable from controls across all MCCB scales. Furthermore, their performance was superior to impaired patients on all scales except Social Cognition. Cognitively normal patients were also superior to impaired patients on a summary index of simulated life skills and functional competence. Nevertheless, both patient groups were equally disadvantaged relative to controls in independent community living. These findings suggest that normal-range cognition exists in schizophrenia, but fails to translate into enhanced community outcome.

The Canadian Objective Assessment of Life Skills (COALS): A new measure of functional competence in schizophrenia

This study examined the reliability and validity of a new performance-based measure of functional competence for individuals with serious mental illness, the Canadian Objective Assessment of Life Skills (COALS). The COALS assesses both routinized procedural knowledge routines (PKR) and executive operations (EXO) in order to capture functional outcome variance. The COALS was administered to 101 outpatients with schizophrenia and schizoaffective disorder and 80 non-psychiatric controls. One month later, 95 patients and 63 controls completed a follow-up assessment. Measures of psychopathology, neurocognition, functionality and community adjustment were also administered. Results indicated that the COALS summary scores had good test-retest reliability for patient data. Further, the COALS correlated with other measures of functionality and with negative symptoms, but was independent of positive symptoms, demonstrating concurrent and discriminant validity. The overall COALS summary score added incremental validity to the prediction of community independence over and above the contribution of symptoms, intellectual ability and neurocognitive performance. Inclusion of EXO scores provided incremental validity not available with PKR scores alone. The COALS increases the number of functional competence instruments and offers the advantage of specific validity while incorporating important distinctions in cognitive performance.