Overweight in midlife and risk of dementia: a 40-year follow-up study.

OBJECTIVE: This study examines whether overweight in midlife increases dementia risk later in life. METHODS: In 1963 body mass index was assessed in 1152 participants of The Swedish Twin Registry, at the age of 45-65 years. These participants were later screened for dementia in a prospective study with up to 40 years follow-up. A total of 312 participants were diagnosed with dementia. RESULTS: Logistic regression analyses adjusted for demographic factors, smoking and alcohol habits, indicated that men and women categorized as overweight in their midlife had an elevated risk of dementia (OR=1.59; 95% CI: 1.21-2.07, P=0.002), Alzheimer's disease (OR=1.71; 95% CI: 1.24-2.35, P=0.003), and vascular dementia (OR=1.55; 95% CI: 0.98-2.47, P=0.059). Further adjustments for diabetes and vascular diseases did not substantially affect the associations, except for vascular dementia (OR=1.36; 95% CI: 0.82-2.56, P=0.116), reflecting the significance of diabetes and vascular diseases in the etiology of vascular dementia. There was no significant interaction between overweight and APOE epsilon4 status, indicating that having both risk factors does not have a multiplicative effect with regard to dementia risk. CONCLUSIONS: This study gives further support to the notion that overweight in midlife increases later risk of dementia. The risk is increased for both Alzheimer's disease and vascular dementia, and follows the same pattern for men and women.

Onset of terminal decline in cognitive abilities in individuals without dementia.

OBJECTIVE: To identify time of onset and rate of mortality-related change (terminal decline) in cognitive abilities in later life. METHOD: The sample consisted of 288 individuals without dementia (born 1901-1902) drawn from the population of Göteborg, Sweden. Participants were followed from age 70 until death, with up to 12 measurement occasions on three cognitive abilities. Change-point analysis was performed using an automated piecewise linear mixed modeling approach to identify the inflection point indicating accelerated within-person change related to mortality. A profile likelihood method was used to identify the change point that best fit the data for each of three cognitive abilities. RESULTS: Onset of terminal decline was identified 6.6 years prior to death for verbal ability, 7.8 years for spatial ability, and 14.8 years for perceptual speed. CONCLUSIONS: There is substantial acceleration in cognitive decline many years prior to death among individuals without dementia. Time of onset and rate of terminal decline vary considerably across cognitive abilities.