Downloaded from http://journals.lww.com/cogbehavneurol by BhDMf5ePHKbH4TTImqenVCbF2BRbWAbds15xIsvPtT2dzLcYoPsq6yjpaHHvJN4I on 06/22/2020 Neurocognitive Impairment in Bipolar Disorder and Associated Factors: Using Population-based Norms and a Strict Criterion for Impairment Definition Stella Maria de Sá Sarmento, MPH,* Lorna Bittencourt, MMH,*† Euclides José de Mendonça Filho, MP,‡ Neander Abreu, PhD,§ Acioly Luiz Tavares de Lacerda, PhD,∥ and Ângela Miranda-Scippa, PhD*¶ Background: Cognitive impairment is often identified in individuals with bipolar disorder and is associated with their functional im- pairment. However, there is controversy surrounding potential classification methods for impairment in cognitive measures. Objective: To examine the proportion of cognitive measures in- dicating impairment of attention, processing speed, memory, visuoconstructional abilities, and executive functions in in- dividuals with bipolar disorder type I (euthymic) and healthy controls, using a strict criterion for defining impairment. Methods: We gave 43 individuals with bipolar disorder type I and 17 healthy controls a comprehensive clinical and neuropsychological assessment. All scores were standardized using means and standard deviations according to age. Impaired performance in all cognitive measures was determined using a distribution-based threshold of z = ± 1645. The effects of the sociodemographic and clinical variables on cognitive performance were examined using multiple stepwise backward regression analyses. Results: Clinically significant cognitive impairment was observed more frequently in the bipolar disorder group, compared to controls, on all measures. From participant factors, we found that level of education and number of manic episodes predicted variation in more cognitive measure scores. Discussion: The use of population-based norms to standardize cognitive measures, and a strict criterion to define cognitive im- pairment, in individuals with bipolar disorder type 1 and healthy controls resulted in a prevalence of impairment in cognitive do- mains’ frequencies of deficits that fell within the ranges pre- viously reported in meta-analyses. Conclusions: Clinically introducing population norms and a stringent cognitive impairment criterion can facilitate more accurate measures of cognitive impairment in individuals with bipolar disorder. Key Words: bipolar disorder type 1, cognitive impairment, euthymic, neuropsychological assessment, cognition (Cogn Behav Neurol 2020;33:103–112) BD = bipolar disorder. BD–I = bipolar disorder type I. HC = healthy control. ROCFT = Rey-Osterreith Complex Figure Test. WAIS– III = Wechsler Adult Intelligence Test—Third Edition. WCST = Wisconsin Card Sorting Test. C ognitive impairment is a feature of several psychiatric diagnoses. It is recognized as an important symptomatic domain in schizophrenia and also manifests in bipolar disorder (BD), major depressive disorder, posttraumatic stress disorder, and obsessive-compulsive disorder (Kim et al, 2018). In fact, cognitive impairment has been described as an endophenotype that is shared by both schizophrenia and BD, which generally exhibit overlap in key clinical symptoms and genetic factors (Memic et al, 2018). Albeit heterogeneous in their expression, the core cognitive symptoms of both disorders include dys- function in working memory, declarative memory, processing speed, and executive functions (Cardenas et al, 2016). Benito et al (2013) reported that, as in schizophrenia, deficits in social cognition aspects such as theory of mind and emotion processing are also a feature of BD. Neu- roimaging techniques have also revealed structural and functional features that can serve as biomarkers of cog- nitive impairment in BD (some of which, again, are shared with schizophrenia) (Shahab et al, 2019; Teixeira et al, 2019). Structural abnormalities include reduced white matter microstructure and volumes within the prefrontal, Received for publication August 21, 2019; accepted December 2, 2019. From the *Program for Mood and Anxiety Disorders, Federal University of Bahia, University Hospital, Bahia, Brazil; †Postgraduate Program in Medicine and Health, Federal University of Bahia, University Hospital, Bahia, Brazil; ‡Federal University of Rio Grande do Sul, Psychology Institute, Porto Alegre, Brazil; §Federal University of Bahia, Psychology Institute, Bahia, Brazil; ∥Department of Psychia- try, Federal University of São Paulo, São Paulo, Brazil; and ¶De- partment of Neurosciences and Mental Health, Federal University of Bahia, Medical School, Bahia, Brazil. Portions of this manuscript were presented as a poster session at the 20th Annual Conference of the International Society for Bipolar Dis- orders, March 2018, Mexico City, Mexico. Supported in part by the Program for Mood and Anxiety Disorders, Federal University of Bahia, University Hospital, Bahia, Brazil. The authors declare no conflicts of interest. Correspondence: Stella Maria de Sá Sarmento, MPH, Professor Edgard Santos University Hospital, Department of Psychiatry, Rua Augusto Viana, s/nº,3º andar, Salvador, BA CEP-40110-060, Brazil (email: stellasa@gmail.com). Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved. ORIGINAL STUDY Cogn Behav Neurol  Volume 33, Number 2, June 2020 www.cogbehavneurol.com | 103 Copyright r 2020 Wolters Kluwer Health, Inc. All rights reserved.