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

Raeanne C Moore; Alexandrea L Harmell; Philip D Harvey; Christopher R Bowie; Colin A Depp; Ann E Pulver; John A McGrath; Thomas L Patterson; Veronica Cardenas; Paula Wolyniec; Mary H Thornquist; James R Luke; Barton W Palmer; Dilip V Jeste; Brent T Mausbach

doi:10.1016/j.schres.2015.09.017

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

Schizophr Res. 2015 Dec;169(1-3):121-127. doi: 10.1016/j.schres.2015.09.017. Epub 2015 Oct 1.

Authors

Affiliations

¹ Department of Psychiatry, University of California, San Diego, United States; Sam and Rose Stein Institute for Research on Aging, University of California, San Diego, CA, United States. Electronic address: r6moore@ucsd.edu.
² Department of Psychiatry, University of California, San Diego, United States; San Diego State University/University of California, San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, United States. Electronic address: aharmell@ucsd.edu.
³ University of Miami Miller School of Medicine, United States. Electronic address: pharvey@med.miami.edu.
⁴ Department of Psychology, Queen's University, Ontario, Canada. Electronic address: bowiec@queensu.ca.
⁵ Department of Psychiatry, University of California, San Diego, United States; Sam and Rose Stein Institute for Research on Aging, University of California, San Diego, CA, United States; VA San Diego Healthcare System, San Diego, CA, United States. Electronic address: cdepp@ucsd.edu.
⁶ Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: aepulver@jhmi.edu.
⁷ Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: jmcgrath@jhmi.edu.
⁸ Department of Psychiatry, University of California, San Diego, United States. Electronic address: tpatterson@ucsd.edu.
⁹ Department of Psychiatry, University of California, San Diego, United States; Sam and Rose Stein Institute for Research on Aging, University of California, San Diego, CA, United States. Electronic address: vcardenas@ucsd.edu.
¹⁰ Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: wolyniec@jhmi.edu.
¹¹ Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: thornquist@jhmi.edu.
¹² Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: jrluke@jhmi.edu.
¹³ Department of Psychiatry, University of California, San Diego, United States; Sam and Rose Stein Institute for Research on Aging, University of California, San Diego, CA, United States. Electronic address: bpalmer@ucsd.edu.
¹⁴ Department of Psychiatry, University of California, San Diego, United States; Sam and Rose Stein Institute for Research on Aging, University of California, San Diego, CA, United States. Electronic address: djeste@ucsd.edu.
¹⁵ Department of Psychiatry, University of California, San Diego, United States; Sam and Rose Stein Institute for Research on Aging, University of California, San Diego, CA, United States. Electronic address: bmausbach@ucsd.edu.

Abstract

Objective: Deficits 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.

Method: Two 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.

Results: Significant 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.

Conclusions: These 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.

Keywords: Cognitive remediation; Disability; Functional capacity; Functioning; Neuropsychological assessment; Serious mental illness.

Published by Elsevier B.V.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Activities of Daily Living
Adolescent
Adult
Aged
Aged, 80 and over
Bipolar Disorder / psychology*
Cognition*
Female
Humans
Linear Models
Male
Middle Aged
Neuropsychological Tests
Psychiatric Status Rating Scales
Schizophrenia*
Schizophrenic Psychology*
Young Adult

Abstract

Publication types

MeSH terms

Grants and funding