The effect of body mass index on cognitive functioning in euthymic bipolar I disorder

Abstract

Objective. The aim of this study was to determine the influence of Body Mass Index (BMI) on cognitive functioning in bipolar disorder type I (BD-I). A previous study suggested that BMI contributes to cognitive decline in BD (Yim et al., 2012). In the present study, this suggestion was tested on a big homogenous group of Dutch patients, while controlled for factors that are known to influence cognitive functioning in BD: medication use, age at onset, and socioeconomic status. Method. A sample of 258 euthymic BD-I patients was recruited from the ‘Bipolar Genetics’ project. Participation included a three hour hospital visit and an 1,5 hour internet survey. For diagnosis and clinical characteristics, the SCID-1 interview for the DSM-IV-TR and QBP-NL were administered. Four subtasks of the WAIS-III were used to measure cognitive functioning. Results. After controlling for the relevant confounders and potential gender- and age effects, negative effects of BMI on cognitive functioning were found. Significance was reached on the WAIS subtasks Digit Symbol-Coding, Information, and Block Design. Conclusion. Results of the present study indicate that BMI independently influences cognitive functioning in BD I patients. This finding implies that weight monitoring is of great importance in clinical practice.