Thyroid function, the risk of dementia and neuropathologic changes: The Honolulu–Asia Aging Study

de Jong, Frank Jan; Masaki, Kamal; Chen, Hepei; Remaley, Alan T.; Breteler, Monique M.B.; Petrovitch, Helen; White, Lon R.; Launer, Lenore J.

doi:10.1016/j.neurobiolaging.2007.07.019

« Previous Next »Neurobiology of Aging
Volume 30, Issue 4 , Pages 600-606, April 2009

Thyroid function, the risk of dementia and neuropathologic changes: The Honolulu–Asia Aging Study

Frank Jan de Jong
- Department of Epidemiology & Biostatistics, Erasmus Medical Center, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
Kamal Masaki
- Pacific Health Research Institute, 846 S Hotel Street, Honolulu, HI 96813, USA
Hepei Chen
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, 7201 Wisconsin Avenue, 3C-309 Bethesda, MD 20892, USA
Alan T. Remaley
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, MD, USA
Monique M.B. Breteler
- Department of Epidemiology & Biostatistics, Erasmus Medical Center, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands
Helen Petrovitch
- Pacific Health Research Institute, 846 S Hotel Street, Honolulu, HI 96813, USA
Lon R. White
- Pacific Health Research Institute, 846 S Hotel Street, Honolulu, HI 96813, USA
Lenore J. Launer
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, 7201 Wisconsin Avenue, 3C-309 Bethesda, MD 20892, USA
- Corresponding author. Tel.: +1 301 496 117; fax: +1 301 496 4006.

Received 5 December 2006; received in revised form 26 June 2007; accepted 28 July 2007. published online 17 September 2007.

Abstract

Thyroid dysfunction is associated with cognitive impairment and dementia, including Alzheimer's disease (AD). It remains unclear whether thyroid dysfunction results from, or contributes to, Alzheimer pathology. We determined whether thyroid function is associated with dementia, specifically AD, and Alzheimer-type neuropathology in a prospective population-based cohort of Japanese-American men. Thyrotropin, total and free thyroxine were available in 665 men aged 71–93 years and dementia-free at baseline (1991), including 143 men who participated in an autopsy sub-study. During a mean follow-up of 4.7 (S.D.: 1.8) years, 106 men developed dementia of whom 74 had AD. Higher total and free thyroxine levels were associated with an increased risk of dementia and AD (age and sex adjusted hazard ratio (95% confidence interval) per S.D. increase in free thyroxine: 1.21 (1.04; 1.40) and 1.31 (1.14; 1.51), respectively). In the autopsied sub-sample, higher total thyroxine was associated with higher number of neocortical neuritic plaques and neurofibrillary tangles. No associations were found for thyrotropin. Our findings suggest that higher thyroxine levels are present with Alzheimer clinical disease and neuropathology.

Keywords: Epidemiology, Thyroid hormones, Thyrotropin, Total thyroxine, Free thyroxine, Dementia, Alzheimer's disease, Neuropathology, Neuritic plaques, Neurofibrillary tangles