A case control study of association between cognition and functional capacity in schizophrenia

https://doi.org/10.1016/j.schres.2015.10.025Get rights and content

Abstract

Background

Cognitive functions are important prognostic factors for schizophrenia (SZ), while ability to perform activities of daily living are important measures of functional capacity. The relationship between cognition and functional capacity has not been tested extensively in India.

Objective

To compare persons with SZ with controls on measures of cognition and functional capacity, and evaluate correlations between cognitive performance and functional capacity.

Method

Schizophrenia outpatients and controls without psychiatric illness (DSM IV) who completed the MATRICS Consensus Cognitive Battery and Functional Assessment Battery comprised of two tests from University of California San Diego (UCSD) Performance Based Skill Assessment (UPSA), one Test of Adaptive Behavior in Schizophrenia (TABS) and one test from University of California San Diego Performance Based Skill Assessment Brief edition (UPSA-B). Cognitive and functional domains were examined using regression analyses, with relevant covariates.

Results

Cases (N = 51) though younger, were more educated than controls (N = 41). Adjusting for education, controls performed better than cases in 3/7 cognitive and 4/5 domains of functional capacity but similarly in ‘household management’. Among both cases and controls, cognitive measures of verbal learning and speed of processing overlapped with functional capacity (3 domains). Working memory was associated with one functional domain.

Conclusions

Consistent with other studies, Indian patients with schizophrenia performed worse than controls on several domains of cognition and functional capacity; these domains were correlated. Speed of processing and verbal learning are most frequently associated with functional capacity indices and should be targeted to improve skills of daily living among persons with SZ.

Introduction

Schizophrenia (SZ) is associated with deficits in several cognitive domains as well as in functional capacity (Keefe et al., 2007, Kraus and Keefe, 2007, Keefe and Harvey, 2012). Cognitive remediation can improve functional outcome in patients with schizophrenia. Since both cognition and functional capacity have several domains, there is a need to identify associations among different domains of cognition and functional capacity.

Functional capacity and real world functioning are different but interrelated domains (Miranda et al., 2015). For focused interventions, significant associations between specified domains of cognition and functional capacity (as reported by Holshausen et al., 2014) need to be targeted. Three domains of real world adaptive functions – interpersonal skills, work skills and community activities – can be assessed by neuropsychological tests (Bowie et al., 2010). The MATRICS consensus cognitive battery was developed and tested all over the world to determine its cultural acceptability and accuracy. A smaller modified version MFAB (MATRICS Functional Assessment Battery) is culturally acceptable and can be used in India (Velligan et al., 2014).

A previous, multicenter study of the ‘Cross-Cultural Reliability and Validity of Intermediate Measures’ (CIM II) of the ‘Measurement and Treatment Research to Improve Cognition in Schizophrenia’ (MATRICS) aimed at investigating the test retest reliability and concurrent validity of several intermediate measures of functional outcome in India and included the present site (Velligan et al., 2014). The present study included all participants from the previous report as well as additional control individuals.

Section snippets

Sites

The study was conducted at the Department of Psychiatry, Post Graduate Institute of Medical Education and Research (PGIMER), Dr. Ram Manohar Lohia Hospital (RMLH), a tertiary care government post graduate teaching hospital in New Delhi, India, from April 2012 to August 2014. RMLH offers services free of charge to all persons seeking treatment.

Participants

The inclusion and exclusion criteria for cases have been published (Velligan et al., 2014). Briefly, psychiatric outpatients with a clinical diagnosis of

Results

A total of 51 patients (34 men and 17 women, ages 18–60 years) and 40 controls (20 men and 20 women, ages 20–60 years) were included. The gender distribution was not statistically different (chi square = 1.88, p = 0.199; 1 df), but the cases were significantly younger than controls (average age — cases: 32.49 ± 9.68; controls: 40.03 ± 11.79; Z = 3.05, p = 0.002). Cases were more educated than controls as education level of controls was restricted to classes 4 to 8.

Discussion

Consistent with prior reports, patients with SZ performed worse than controls on cognitive measures. We also found differences in domains of work and productivity between cases and controls similar to those reported by Nuechterlein et al. (2011). The ability to plan and execute a task (cognition) is critical for performance in day to day activities such as money planning or cooking (functional capacity). Thus, deficits in cognition would lead to impairment in functional capacity. As indicated

Conclusion

At a site in India, control individuals performed better than patients with SZ in 3/7 cognitive domains and 4/5 domains of functional capacity. Patients with schizophrenia performed worse than controls in cognitive domains of attention and problem solving. Functional capacity was also impaired. With regard to the household management domain, performance of cases and controls was similar. The cognitive domains most likely to be associated with functional capacity were speed of processing and

Role of funding source

In addition to a grant from the University of Texas (DV), this study was funded in part by grants from the National Institutes of Health, USA (Tri National Training Program in Psychiatric Genetics (D43 TW008302) and the Training Program for Psychiatric Genetics in India (D43 TW 06167 to VLN) and the Stanley Medical Research Institute (07R-1712 to VLN). The salary of TB is supported by FIC, NIH funded project “Impact of Yoga supplementation on cognitive function among Indian outpatients with

Contributors

Sreelatha S. Narayanan: data acquisition, review of literature, preparation of manuscript.

Triptish Bhatia: design for cognitive variables and data analysis.

Dawn I. Velligan: design of original study, manuscript review.

Vishwajit L. Nimgaonkar: concept, manuscript review.

Smita N. Deshpande: concept, design and manuscript review and editing.

Conflict of interest

There is no conflict of interest to be declared by any of the authors.

Acknowledgments

We thank our study participants and the doctors at Dept. of Psychiatry, PGIMER, Dr. R.M.L. Hospital who referred them to us. In addition to a grant from the University of Texas (DV), this study was funded in part by grants from the National Institutes of Health, USA (D43 TW008302 and D43 TW06167 to VLN) and the Stanley Medical Research Institute (07R-1712 to VLN).

References (18)

There are more references available in the full text version of this article.

Cited by (0)

View full text