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Midlife Risk Factors for Subtypes of Dementia: A Nested Case-Control Study in Taiwan

https://doi.org/10.1097/JGP.0b013e318050c98fGet rights and content

Objective

To identify the midlife risk factors for subtypes of dementia newly developed later in life.

Methods

A nested case-control study was conducted on 157 demented cases and 628 comparison cases selected from 40,636 men and women who were enrolled from 1982 to 1992. Four comparison cases were frequency-matched on age, time at enrollment (within 6 months), gender, and residential township. Midlife risk factors included vascular risk factors (body mass index [BMI], total cholesterol, total triglycerides, blood glucose, cerebrovascular accident [CVA] history, diabetes mellitus history, and hypertension history), cigarette smoking, and alcohol consumption. Dementia assessments were ascertained through the computerized data linkage from National Health Insurance Database from 2000 to 2002 and clinically confirmed by neurologists or psychiatrists. Conditional logistic regression analysis was used to estimate the matched odds ratio (OR) and its 95% confidence intervals (CI) for each risk factor.

Results

A J-shaped relationship was observed between BMI (kg/m2) and dementia. The multivariate-adjusted ORs (95% CI) of developing dementia were 1.84 (1.02–3.33), 1.87 (1.08–3.23) and 2.44 (1.39–4.28), respectively, for BMIs of <20.5, 23.0–25.4, ≥25.5 compared with a BMI of 20.5–22.9 as the referent group (OR = 1.0). Similar findings were observed for Alzheimer disease (AD) and vascular dementia (VaD). The association between obesity (BMI ≥25.5) and both AD and VaD was statistically significant among cigarette smokers but not among nonsmokers. Additionally, history of CVA was a significant risk factor for VaD, but not for AD.

Conclusion

Being underweight, being overweight, and a cerebrovascular accident in midlife may increase the risk of dementia in late life.

Section snippets

Study Cohort

This study was nested in two cohort studies, the Multiple Risk factors for Major Diseases (MRMD)20 and the community-based Cancer Screening Program (CSP).21 The MRMD cohort study recruited residents from 12 townships and precincts including Nankang, Nantzu, Tayuan, Tashu, Tounan, Chunan, Kuanhsi, Hsinpu, Hengshan, Yuanshan, Chutien, and Checheng between October 1982 and March 1986. The CSP cohort study recruited adult residents from another seven townships and precincts including Shanchi,

RESULTS

Among 157 dementia cases, 64 (40.8%) had AD, 54 (34.4%) had VaD, 9 (5.7%) had MD, and 30 (19.1%) had other types of dementia. The leading dementia types were AD and VaD. Among AD, VaD, and MD cases, patients aged ≥60 years in 2001 were 62 (96.9%) for AD, 53 (98.1%) for VaD, and 9 (100%) for MD (data not shown). There were 92 male and 65 female dementia patients as well as 368 male and 260 female comparison cases. The mean (SD) of age at enrollment was 57.9 (7.4) for dementia cases and 57.8

DISCUSSION

The advantage of this case-control study nested within a large population-based cohort is the collection of data for risk factors in midlife before the onset of dementia. The study avoided systematic recall bias, which might occur in cross-sectional case-control studies. This study also established the causal temporality between risk factor exposure and development of dementia.

The results of this study revealed a J-shaped relationship between BMI in midlife and the risk of AD and VaD later in

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    • Cited by (0)

    The authors thank neurologists and psychiatrists of the 34 hospitals in Taiwan for providing confirmation of diagnosis in this study.

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    Copyright © 2007 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.