Midlife and late-life body mass index and late-life dementia: results from a prospective population-based cohort.
BACKGROUND
Obesity has been consistently associated with dementia. The role of certain risk factors of dementia may change during life, and the importance of having a life-course perspective has been acknowledged.


OBJECTIVE
The aim of this study was to investigate the association of midlife and late-life body mass index (BMI) with late-life dementia/Alzheimer's disease (AD) and whether the association was independent of other obesity-related co-morbidities.


METHODS
The association between midlife BMI (mean age 50.2, SD 6.0) and late-life BMI (mean age 71.2, SD 4.0) and incident dementia later in life (mean age 75.7, SD 5.0) were investigated among 1,304 participants of the longitudinal population-based Cardiovascular risk factors, Aging and Dementia (CAIDE) study, conducted in Eastern Finland. The duration of follow-up was 26 years. The diagnosis of dementia was based on DSM-IV criteria and the probable and possible AD on the NINCDS-ADRDA criteria.


RESULTS
Higher midlife BMI was associated with higher risk of incident dementia (adjusted HR, 95% CI 1.07, 1.00-1.14). However, decrease in BMI from midlife to late-life was associated with higher risk of dementia (1.14, 1.03-1.25 for one-unit decrease) and AD (1.20, 1.09-1.33). High late-life BMI was associated with lower risk of AD (0.89, 0.81-0.98) but the association with dementia was less evident (0.94, 0.86-1.03).


CONCLUSIONS
Higher midlife BMI is related to higher risk of dementia and AD, independently of obesity-related risk factors and co-morbidities. Steeper decrease of BMI and low late-life BMI are associated with higher risk of dementia and AD. These findings highlight the importance of life-course perspective when assessing the association between BMI and cognition.
Department of Neurology, University of Eastern Finland, P.O. Kuopio, Finland.
Anna-Maija
AM
Tolppanen
Tiia
T
Ngandu
Ingemar
I
Kåreholt
Tiina
T
Laatikainen
Minna
M
Rusanen
Hilkka
H
Soininen
Miia
M
Kivipelto
D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D015992:Body Mass Index; D015331:Cohort Studies; D018672:Community Health Planning; D003704:Dementia / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000150:complications / Q000453:epidemiology*; D012307:Risk Factors
Alzheimer's disease; body mass index; dementia; obesity