Sex-Differential Associations Between Body Mass Index and the Incidence of Dementia

Article type: Research Article

Authors: Jacob, Louis^{a; b} | Smith, Lee^c | Koyanagi, Ai^{a; d} | Konrad, Marcel^e | Haro, Josep Maria^a | Shin, Jae Il^f | Kostev, Karel^{g; *}

Affiliations: [a] Research and Development Unit, Parc Sanitari Sant Joan de Déu, CIBERSAM, ISCIII, Dr. Antoni Pujadas, Sant Boi de Llobregat, Barcelona, Spain | [b] Faculty of Medicine, University of Versailles Saint-Quentin-en-Yvelines, Montigny-le-Bretonneux, France | [c] Centre for Health, Performance and Wellbeing, Anglia Ruskin University, Cambridge, UK | [d] Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluis Companys, Barcelona, Spain | [e] Health & Social, FOM University of Applied Sciences for Economics and Management, Frankfurt am Main, Germany | [f] Department of Pediatrics, Yonsei University College of Medicine, Seoul, Republic of Korea | [g] Epidemiology, IQVIA, Frankfurt, Germany

Correspondence: [*] Correspondence to: Prof. Dr. rer. med. Karel Kostev, Epidemiology, IQVIA, Unterschweinstiege 2-14, 60549 Frankfurt am Main, Germany. Tel.: +49 0 69 66 04 4878; E-mail: karel.kostev@iqvia.com.

Abstract: Background:Little is known about the sex differences in the association between body mass index (BMI) and dementia in late life. Objective:Therefore, this retrospective cohort study aimed to analyze associations between BMI and dementia in older women and men separately in general practices in Germany. Methods:This study included patients followed in one of 832 general practices in Germany between 2006 and 2019 (index date: first visit date). Study variables included dementia (dependent variable), BMI (independent variable), age, sex, and comorbidities (control variables). Kaplan-Meier curves and adjusted Cox regression analyses were conducted to analyze associations between BMI and the 10-year incidence of dementia in women and men, separately. Results:There were 296,767 patients included in this study (mean [standard deviation] age 70.2 [5.9] years; 54.3% women). The proportion of underweight, normal weight, overweight, and obesity was 0.9%, 25.5%, 41.5%, and 32.1%, respectively. The 10-year incidence of dementia significantly decreased with increasing BMI, from 11.5% in women with underweight to 9.1% in those with obesity (log-rank p < 0.001). Respective figures in men were 12.0% and 8.2% (log-rank p < 0.001). In women, only overweight (versus normal weight) was significantly associated with dementia (HR = 0.93, 95% CI = 0.88–0.97). In contrast, in men, the only BMI category significantly associated with the incidence of dementia was underweight (HR = 1.58, 95% CI = 1.11–2.25). Conclusion:In this study conducted in Germany, overweight was negatively associated with dementia in women, whereas there was a positive underweight-dementia relationship in men. More data are needed to confirm or refute these findings in other settings.

Keywords: Body mass index, dementia, Germany, retrospective cohort study, sex differences

DOI: 10.3233/JAD-220147

Journal: Journal of Alzheimer's Disease, vol. 88, no. 2, pp. 631-639, 2022