Impacts of Overweight and Obesity in Older Age on the Risk of Dementia: A Systematic Literature Review and a Meta-Analysis - PubMed (original) (raw)

Meta-Analysis

doi: 10.3233/JAD-180763.

Angela Clifford 1, Martin Partridge 1, Weiju Zhou 1, Aishat T Bakre 1, Anthony Chen 2, Danielle McFeeters 1, Tina Smith 1, Yuhui Wan 3, John Copeland 4, Kaarin J Anstey 5, Ruoling Chen 1

Affiliations

Meta-Analysis

Impacts of Overweight and Obesity in Older Age on the Risk of Dementia: A Systematic Literature Review and a Meta-Analysis

Isaac M Danat et al. J Alzheimers Dis. 2019.

Abstract

Background: It is unclear whether overweight and obesity in older age reduces or increases the risk of incident dementia.

Objective: To assess the impacts of overweight and obesity in older age on incident dementia.

Methods: We searched cohort studies reporting body weight measured in older age and dementia through PubMed, Embase, Medline, PyschInfo, and Cochrane library until July 2016. Sixteen articles were identified for the review. We pooled data from them and a new unpublished study from China, to calculate relative risk (RR) of incident dementia in relation to body mass index (BMI) and waist circumference (WC).

Results: All 16 cohort studies were undertaken in high income countries, with follow-up periods ranging between 3 to 18 years. Thirteen studies showed an inverse association between BMI and dementia, and three studies demonstrated a positive association. Pooled RR of dementia in relation to continuous BMI from 14 studied populations, including the new Chinese data, was 0.97 (95% CI 0.95-1.00); in those followed up <9 years it was 0.95 (0.93-0.96) while in ≥9 years follow-up it was 1.03 (0.96-1.11). In five studied populations examining categorical BMI, RR of dementia in older people classified as overweight and obese was 0.98 (0.54-1.77) and 1.17 (0.65-2.10) respectively, in comparison with other weights. The pooled WC data showed no association between increased WC and reduced risk of dementia.

Conclusion: The current evidence did not support a paradox on beneficial impacts of overweight and obesity in older age on incident dementia. More studies with long term follow up are needed to clarify the association of body weight in older age with dementia risk.

Keywords: Body weight; dementia; meta-analysis; older people.

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Conflict of interest statement

Authors’ disclosures available online (https://www.j-alz.com/manuscript-disclosures/18-0763r1).

Figures

Fig.1

Fig.1

Flowchart for literature search, selection, and inclusion of studies for the research. *Reasons included: studied midlife or younger baseline age <65 years, other outcome variables such as MCI, dementia+MCI, did not assess the key predictor (BMI or WC), different study design (such as cross-sectional or case control), etc. ∼Two studies were not used for meta-analysis due to fewer adjustments for co-variates.

Fig.2

Fig.2

Forest plot showing pooled estimates of all included studies for BMI and dementia risk. Three studies, i.e., in low part of the figure, did not examine the association of continuous BMI and dementia, and thus the overall meta-analysis took their data of categorized BMI in the highest group. f, female; m, male.

Fig.3

Fig.3

Continuous BMI and dementia risk (short term versus long term follow up). In total, 11,376 participants with 1,741 dementia cases for short term and in total 5,198 participants with 631 dementia cases for long term studies. f, female; m, male.

Fig.4

Fig.4

Forest plots for large and larger waist circumference and dementia risk. f, female; m, male.

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