The Journals of Gerontology Series A: Biological Sciences and Medical Sciences Advance Access published online on April 6, 2009
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, doi:10.1093/gerona/glp035
Being Overweight in Midlife Is Associated With Lower Cognitive Ability and Steeper Cognitive Decline in Late Life
1 Institute of Gerontology, School of Health Sciences, Jönköping University, Sweden
2 Department of Psychology, University of Gothenburg, Sweden
3 Department of Psychology, University of Southern California, Los Angeles
4 Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
5 Department of Psychology, University of California, Riverside
Address correspondence to Anna Dahl, MS, Institute of Gerontology, School of Health Sciences, Jönköping University, Box 1026, Jönköping 551 11, Sweden. Email: anna.dahl{at}hhj.hj.se
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Abstract |
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Background: Although an increasing body of evidence links being overweight in midlife with an increased risk for dementia in late life, no studies have examined the association between being overweight in midlife and cognitive ability in late life. Our aim was to examine the association between being overweight in midlife as measured by body mass index (BMI) and cognitive ability assessed over time.
Methods: Participants in the Swedish Adoption/Twin Study Aging were derived from a population-based sample. The participants completed baseline surveys in 1963 or 1973 (mean age 41.6 years, range 25–63 years). The surveys included questions about height, weight, diseases, and lifestyle factors. Beginning in 1986, the same individuals were assessed on neuropsychological tests every 3 years (except in 1995) until 2002. During the study period, 781 individuals who were 50 years and older (60% women) had at least one complete neuropsychological assessment. A composite score of general cognitive ability was derived from the cognitive test battery for each measurement occasion.
Results: Latent growth curve models adjusted for twinness showed that persons with higher midlife BMI scores had significantly lower general cognitive ability and significantly steeper longitudinal decline than their thinner counterparts. The association did not change substantially when persons who developed dementia during the study period were excluded from the analysis.
Conclusions: Higher midlife BMI scores precede lower general cognitive ability and steeper cognitive decline in both men and women. The association does not seem to be mediated by an increased risk for dementia.
Keywords Body mass index; Cognition; Dementia; Epidemiology
Received: August 28, 2008; Accepted: January 23, 2009