Prediction of Real-World Functional Disability in Chronic Mental Disorders: A Comparison of Schizophrenia and Bipolar Disorder

OBJECTIVE: Schizophrenia (SZ) and Bipolar Disorder (BD) are associated with multidimensional disability. This study examined differential predictors of functional deficits between the disorders. METHODS: Community dwelling individuals with SZ (N=161) or BD (N=130) were administered neuropsychological tests, symptom measures, performance-based social and adaptive (i.e., everyday-living skills) functional competence measures, and rated on domains of real-world functioning: 1) Community and Household activities, 2) Work skills, and 3) Interpersonal relationships. We used confirmatory path analysis to find the best fitting models to examine the direct and indirect (as mediated by competence) prediction of the three domains of real-world functioning. RESULTS: In all models for both groups, neurocognition’s relationship with outcomes was largely mediated by competence. Symptoms were negatively associated with outcomes but unassociated with competence, with the exception of depression, which was a direct and mediated (through social competence) predictor in BD. In both groups, neurocognition was related to Activities directly and through a mediated relationship with adaptive competence. Work Skills were directly and indirectly (through mediation with social competence) predicted by neurocognition in SZ and entirely mediated by adaptive and social competence in BD. Neurocognition was associated with Interpersonal Relationships directly in the SZ group, and mediated by social competence in both groups. CONCLUSIONS: Although there was greater disability in SZ, neurocognition predicted worse functioning in all outcome domains in both disorders. Our study supports the shared role of neurocognition in BD and SZ in producing disability, with predictive differences between disorders observed in domain-specific effects of symptoms and social and adaptive competence

Determinants of occupational and residential functioning in bipolar disorder

Bipolar disorder is associated with reduced rates of employment and residential independence. The influence of cognitive impairment and affective symptoms on these functional attainments has received little previous attention and is the focus of this study. A total of 229 adult outpatients with bipolar disorder without active substance use disorders and with an average of mild severity of affective symptoms were included in the analyses. After adjusting for sociodemographic and illness history covariates, univariate and multivariate analyses were used to evaluate the independent and interactive associations of neurocognitive ability, performance-based functional capacity, and affective symptom severity with residential independence, occupational status and number of hours worked. A total of 30% of the sample was unemployed and 18% was not independently residing. Neurocognitive ability was the strongest predictor of any employment, but depressive symptom severity was the only variable significantly related to hours worked. The strongest predictor of residential independence was performance-based functional capacity. Affective symptoms and neurocognitive ability were independent (non-interactive) predictors of occupational and residential status. This is a cross-sectional study and thus causal direction among variables is unknown. The sample was ethnically homogeneous and thus the results may not generalize to ethnically diverse samples. This study confirmed elevated rates of unemployment and residential non-independence in adults with bipolar disorder. Interventions targeting cognitive deficits and functional capacity may increase the likelihood of any employment or residential independence, respectively. Interventions targeting depressive symptoms may be most influential on work outcomes among those already employed

Relationship of the Brief UCSD Performance-based Skills Assessment (UPSA-B) to multiple indicators of functioning in people with schizophrenia and bipolar disorder

OBJECTIVE: This study assessed the relationship between multiple indicators of ‘real-world’ functioning and scores on a brief performance-based measure of functional capacity known as the Brief University of California San Diego (UCSD) Performance-based Skills Assessment (UPSA-B) in a sample of 205 patients with either serious bipolar disorder (n = 89) or schizophrenia (n = 116). METHODS: Participants were administered the UPSA-B and assessed on the following functional domains: (i) independent living status (e.g., residing independently as head of household, living in residential care facility); (ii) informant reports of functioning (e.g., work skills, daily living skills); (iii) educational attainment and estimated premorbid IQ as measured by years of education and Wide Range Achievement Test reading scores, respectively; and (iv) employment. RESULTS: Better scores on the UPSA-B were associated with greater residential independence after controlling for age, diagnosis, and symptoms of psychopathology. Among both bipolar disorder and schizophrenia patients, higher UPSA-B scores were significantly related to better informant reports of functioning in daily living skills and work skills domains. Greater estimated premorbid IQ was associated with higher scores on the UPSA-B for both schizophrenia and bipolar disorder participants. Participants who were employed scored higher on the UPSA-B when controlling for age and diagnosis, but not when controlling for symptoms of psychopathology. CONCLUSIONS: These data suggest the UPSA-B may be useful for assessing capacity for functioning in a number of domains in both people diagnosed with schizophrenia and bipolar disorder

Current Smoking is Associated with Worse Cognitive and Adaptive Functioning in Serious Mental Illness

OBJECTIVE: Cigarette smoking is highly prevalent among people with bipolar disorder or schizophrenia. Few studies have examined whether smoking history is associated with adaptive functioning among individuals diagnosed with these serious mental illnesses. METHOD: In a large relatively homogenous cohort of patients with either bipolar disorder (n=363) or schizophrenia (n=400), we investigated the association between cigarette smoking status, intensity, and cumulative exposure and performance on a comprehensive battery of neurocognitive, functional capacity, informant-rated functional measures. The associations were adjusted for variation in sociodemographic indicators, psychopathologic symptoms, and substance use. RESULTS: There was an average of 12 pack years of smoking across the sample. People with schizophrenia reported double the rate of current smoking compared to patients with bipolar disorder. Adjusting for demographic covariates, current smokers had worse composite cognitive functioning and poorer functional outcome than past or never smokers. There were no significant differences between never and past smokers, and these effects were evident in both bipolar disorder and schizophrenia. CONCLUSION: Current smokers with either schizophrenia or bipolar disorder evidence worse cognitive and adaptive functioning functional outcome, even when demographic covariates are considered. SIGNIFICANT OUTCOMES: Patients with schizophrenia had double the rate of smoking compared to patients with bipolar disorder. Current smoking was negatively associated with cognitive functioning, functional capacity, and informant reported functional outcomes in both patients with schizophrenia and bipolar disorder, after adjusting for sociodemographic covariates. LIMITATIONS: The study was cross-sectional and so causal associations cannot be inferred. Tobacco use was assessed with a self-report instrument. The sample was relatively homogenous and high function and may not generalize to ethnically diverse or more symptomatic samples

Social competence and observer-rated social functioning in bipolar disorder

OBJECTIVE: Impairment in social functioning appears to be common in bipolar disorder, although estimates have been derived largely from self-report measures. We examined performance-based and observer-based ratings of social competence and functioning and assessed the contribution of symptoms and neurocognitive ability to social functioning in bipolar disorder. METHODS: In this cross-sectional study, 164 subjects with bipolar disorder were administered the performance-based Social Skills Performance Assessment (SSPA), rated by an informant on the Specific Level of Functioning (SLOF)–Interpersonal subscale, received clinical ratings of depression and manic symptoms, and performed neurocognitive tests. We assessed the proportion of patients exhibiting social deficits and examined the associations between composite measures of neurocognitive ability, depression and manic symptoms, and SSPA scores with informant-rated, real-world social functioning. RESULTS: Mean age of the sample was 47.6 years (SD = 14.1). Subjects were experiencing, on average, mild levels of depression and minimal manic symptoms. A total of 29% exhibited norm-referenced impairment on the SSPA, and 64% registered at least one impairment on SLOF items; unemployed subjects had lower SSPA and SLOF ratings. Neurocognitive performance correlated with both performance-based and observer-rated social functioning, whereas depressive and manic symptoms correlated only with observer-rated social impairments. In multivariate models, depression was the most potent association with social functioning, and impairment in social competence (i.e., capacity) increased the strength of the relationships between depression and neurocognitive impairment and social functioning (i.e., real-world functioning). CONCLUSIONS: Our study confirmed the negative relationship of bipolar depression with social functioning. A subgroup of outpatients with bipolar disorder has impaired social competence, which, when present, worsened the impact of depression and cognitive impairment on social functioning

Association of obesity and treated hypertension and diabetes with cognitive ability in bipolar disorder and schizophrenia.

ObjectivesPeople with bipolar disorder or schizophrenia are at greater risk for obesity and other cardio-metabolic risk factors, and several prior studies have linked these risk factors to poorer cognitive ability. In a large ethnically homogenous outpatient sample, we examined associations among variables related to obesity, treated hypertension and/or diabetes and cognitive abilities in these two patient populations.MethodsIn a study cohort of outpatients with either bipolar disorder (n = 341) or schizophrenia (n = 417), we investigated the association of self-reported body mass index and current use of medications for hypertension or diabetes with performance on a comprehensive neurocognitive battery. We examined sociodemographic and clinical factors as potential covariates.ResultsPatients with bipolar disorder were less likely to be overweight or obese than patients with schizophrenia, and also less likely to be prescribed medication for hypertension or diabetes. However, obesity and treated hypertension were associated with worse global cognitive ability in bipolar disorder (as well as with poorer performance on individual tests of processing speed, reasoning/problem-solving, and sustained attention), with no such relationships observed in schizophrenia. Obesity was not associated with symptom severity in either group.ConclusionsAlthough less prevalent in bipolar disorder compared to schizophrenia, obesity was associated with substantially worse cognitive performance in bipolar disorder. This association was independent of symptom severity and not present in schizophrenia. Better understanding of the mechanisms and management of obesity may aid in efforts to preserve cognitive health in bipolar disorder

Improving the understanding of the link between cognition and functional capacity in schizophrenia and bipolar disorder.

ObjectiveDeficits in cognitive functioning are related to functional disability in people with serious mental illness. Measures of functional capacity are commonly used as a proxy for functional disabilities for cognitive remediation programs, and robust linear relationships between functional capacity and cognitive deficits are frequently observed. This study aimed to determine whether a curvilinear relationship better approximates the association between cognitive functioning and functional capacity.MethodTwo independent samples were studied. Study 1: participants with schizophrenia (n=435) and bipolar disorder (n=390) aged 18-83 completed a neuropsychological battery and a performance-based measure of functional capacity. Study 2: 205 participants with schizophrenia (age range=39-72) completed a brief neuropsychological screening battery and a performance-based measure of functional capacity. For both studies, linear and quadratic curve estimations were conducted with cognitive performance predicting functional capacity scores.ResultsSignificant linear and quadratic trends were observed for both studies. Study 1: in both the schizophrenia and bipolar participants, when cognitive composite z-scores were >0 (indicating normal to above normal performance), cognition was not related to functional capacity. Study 2: when neuropsychological screening battery z-scores were >-1 (indicating low average to average performance), cognition was not related to functional capacity.ConclusionsThese results illustrate that in cognitively normal adults with serious mental illness, the relationship between cognitive function and functional capacity is relatively weak. These findings may aid clinicians and researchers determine who may optimally benefit from cognitive remediation programs, with greater benefits possibly being achieved for individuals with cognitive deficits relative to individuals with normal cognition

Improving the understanding of the link between cognition and functional capacity in schizophrenia and bipolar disorder.

ObjectiveDeficits in cognitive functioning are related to functional disability in people with serious mental illness. Measures of functional capacity are commonly used as a proxy for functional disabilities for cognitive remediation programs, and robust linear relationships between functional capacity and cognitive deficits are frequently observed. This study aimed to determine whether a curvilinear relationship better approximates the association between cognitive functioning and functional capacity.MethodTwo independent samples were studied. Study 1: participants with schizophrenia (n=435) and bipolar disorder (n=390) aged 18-83 completed a neuropsychological battery and a performance-based measure of functional capacity. Study 2: 205 participants with schizophrenia (age range=39-72) completed a brief neuropsychological screening battery and a performance-based measure of functional capacity. For both studies, linear and quadratic curve estimations were conducted with cognitive performance predicting functional capacity scores.ResultsSignificant linear and quadratic trends were observed for both studies. Study 1: in both the schizophrenia and bipolar participants, when cognitive composite z-scores were >0 (indicating normal to above normal performance), cognition was not related to functional capacity. Study 2: when neuropsychological screening battery z-scores were >-1 (indicating low average to average performance), cognition was not related to functional capacity.ConclusionsThese results illustrate that in cognitively normal adults with serious mental illness, the relationship between cognitive function and functional capacity is relatively weak. These findings may aid clinicians and researchers determine who may optimally benefit from cognitive remediation programs, with greater benefits possibly being achieved for individuals with cognitive deficits relative to individuals with normal cognition