title: Improving the understanding of the link between cognition and functional capacity in schizophrenia and bipolar disorder.
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.
  
  
  METHODS
  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.
authors.affiliation: 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.
authors.forename: Raeanne C
authors.initials: RC
authors.lastname: Moore
authors.affiliation: 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.
authors.forename: Alexandrea L
authors.initials: AL
authors.lastname: Harmell
authors.affiliation: University of Miami Miller School of Medicine, United States. Electronic address: pharvey@med.miami.edu.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Harvey
authors.affiliation: Department of Psychology, Queen's University, Ontario, Canada. Electronic address: bowiec@queensu.ca.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Bowie
authors.affiliation: 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.
authors.forename: Colin A
authors.initials: CA
authors.lastname: Depp
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: aepulver@jhmi.edu.
authors.forename: Ann E
authors.initials: AE
authors.lastname: Pulver
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: jmcgrath@jhmi.edu.
authors.forename: John A
authors.initials: JA
authors.lastname: McGrath
authors.affiliation: Department of Psychiatry, University of California, San Diego, United States. Electronic address: tpatterson@ucsd.edu.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Patterson
authors.affiliation: 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.
authors.forename: Veronica
authors.initials: V
authors.lastname: Cardenas
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: wolyniec@jhmi.edu.
authors.forename: Paula
authors.initials: P
authors.lastname: Wolyniec
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: thornquist@jhmi.edu.
authors.forename: Mary H
authors.initials: MH
authors.lastname: Thornquist
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, United States. Electronic address: jrluke@jhmi.edu.
authors.forename: James R
authors.initials: JR
authors.lastname: Luke
authors.affiliation: 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.
authors.forename: Barton W
authors.initials: BW
authors.lastname: Palmer
authors.affiliation: 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.
authors.forename: Dilip V
authors.initials: DV
authors.lastname: Jeste
authors.affiliation: 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.
authors.forename: Brent T
authors.initials: BT
authors.lastname: Mausbach
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001714:Bipolar Disorder / Q000523:psychology*; D003071:Cognition; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia; D012565:Schizophrenic Psychology; D055815:Young Adult
keywords: Cognitive remediation; Disability; Functional capacity; Functioning; Neuropsychological assessment; Serious mental illness