Highlights
- •Education reduced the dementia death risk when follow-up started in adulthood.
- •This protective effect was robust to adjustment.
- •Education had no protective effect when follow-up started in old age.
- •This could imply that education delays onset, but not the late phases of dementia.
Abstract
An inverse relationship between educational level and dementia has been reported in
several studies. In this study we investigated the relationship between educational
level and dementia related deaths for cohorts of people all born during 1915–39. The
cohorts were followed up from adulthood or old age, taking into account possible confounders
and mediating paths. Our study population comprised participants in Norwegian health
examination studies in the period 1974–2002; The Counties Study and Cohort of Norway
(CONOR). Dementia related deaths were defined as deaths with a dementia diagnosis
on the death certificate and linked using the Cause of Death Registry to year 2012.
The study included 90,843 participants, 2.06 million person years and 2440 dementia related deaths. Cox regression was used to
assess the association between education and dementia related deaths. Both high and
middle educational levels were associated with lower dementia related death risk compared
to those with low education when follow-up started in adulthood (35–49 years, high versus low education: HR = 0.68, 95% confidence interval (CI) 0.50–0.93; 50–69 years, high versus low education: HR = 0.52, 95% CI 0.34–0.80). However, when follow-up started at old age (70–80 years) there was no significant association between education and dementia related
death. Restricting the study population to those born during a five-year period 1925–29
(the birth cohort overlapping all three age groups), gave similar main findings. The
protective effects found for both high and middle educational level compared to low
education were robust to adjustment for cardiovascular health and life style factors,
suggesting education to be a protective factor for dementia related death. Both high
and middle educational levels were associated with decreased dementia related death
risk compared with low educational level when follow-up started in adulthood, but
no association was observed when follow-up started at old age.
Keywords
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Article info
Publication history
Published online: July 09, 2014
Accepted:
July 3,
2014
Received in revised form:
June 24,
2014
Received:
February 17,
2014
Identification
Copyright
© 2014 Elsevier B.V. Published by Elsevier Inc. All rights reserved.
