Introduction: Nearly every individual with schizophrenia is affected by cognitive decline. The aim of this literature review was to: (a) describe the humanistic burden of cognitive impairment associated with schizophrenia (CIAS); (b) develop a conceptual model that depicts the signs and symptoms of CIAS along with key concepts important to patients; and (c) consider the adequacy of potential patient-reported outcome (PRO) instruments for assessing future treatments.
Methods: The following electronic databases were searched for articles published between January 1999 and November 2009 related to CIAS and PROs, or cost of illness: Medline; Embase; PsycINFO; the Health Economic Evaluation Database; and the National Health Service Economic Evaluation Database and Health Technology Assessment databases at the Centre for Reviews and Dissemination, University of York.
Results: The literature search revealed 3950 abstracts, of which 101 articles were reviewed in detail. Cognitive functions affected include memory, attention/concentration, problem solving, learning, executive function, processing speed, and social cognition. Cognitive impairment impacts the ability of individuals to carry out activities of daily living, work productively, function socially, and adhere to treatment. These effects have economic ramifications through increased direct and indirect costs associated with the treatment of schizophrenia. The literature revealed 39 PRO instruments that have been used to assess functioning. However, no single instrument captures all key concepts of importance to patients with schizophrenia.
Conclusion: The significant burden from CIAS for patients and society has implications for designing future treatments and health strategies to improve functional outcomes.