To The Editor: Drs. Beck and Grant call to our attention the very important point that the influence of cognitive functioning on everyday outcomes is affected by the presence of defeatist attitudes. These attitudes have a mediating effect and supplement the influence of cognitive impairment in the prediction of everyday outcomes. Thus, competence (i.e., what one can do, such as cognitive performance) is only one of several predictors of real-world functional performance (i.e., what one actually does). In fact, we previously demonstrated that there are multiple competence domains of importance, including neuropsychological performance and the capacity to perform everyday living and social activities (i.e., functional capacity) (1). Both of these competence variables were described in the three Measurement and Treatment Research to Improve Cognition in Schizophrenia articles discussed in our editorial. Although defeatist attitudes are clear mediators, there are other factors that may also mediate between neurocognitive functioning and everyday outcomes, including patients’ psychological characteristics (e.g., depression, motivational factors, social and cognitive abilities) as well as societal and individual factors (e.g., disability compensation, ethnicity). In the effort to account for everyday impairment in individuals with schizophrenia, it appears that a well-defined separation of competence, performance, and mediating factors will lead to the most distinct analysis of contributors to this impairment. These distinctions could result in important treatment implications, since pharmacological and psychosocial treatments are unlikely to affect all of the multiple influences on impairment equally, and they are unlikely to affect some of these influences at all.
1.Bowie CR, Reichenberg A, Patterson TL, Heaton RK, Harvey PD: Determinants of real-world functional performance in schizophrenia subjects: correlations with cognition, functional capacity, and symptoms. Am J Psychiatry 2006; 163:418–425
The author’s disclosures accompany the original article.
This letter (doi: 10.1176/appi.ajp.2008.08020229r) was accepted for publication in March 2008.