Format

Send to

Choose Destination
Clin Endocrinol (Oxf). 2017 Nov;87(5):617-626. doi: 10.1111/cen.13458. Epub 2017 Sep 14.

The association between subclinical thyroid dysfunction and dementia: The Health, Aging and Body Composition (Health ABC) Study.

Author information

1
Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
2
Departments of Medicine and Epidemiology & Biostatistics, University of California, San Francisco, CA, USA.
3
Institute of Primary Health Care (BIHAM), University of Bern, Bern, Switzerland.
4
Department of Diabetes, Endocrinology, Clinical Nutrition and Metabolism, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
5
Intramural Research Program, National Institute on Aging, Baltimore, MD, USA.
6
Departments of Psychiatry, and Neurology, University of California, San Francisco, CA, USA.
7
Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.

Abstract

OBJECTIVE:

Data on the association between subclinical thyroid dysfunction and dementia are limited and conflicting. We aimed to determine whether subclinical thyroid dysfunction was associated with dementia and cognitive decline.

DESIGN:

Population-based prospective cohort study.

PATIENTS:

Adults aged 70-79 years with measured thyroid function, but no dementia at baseline, and Modified Mini-Mental State (3MS) at baseline and follow-up.

MEASUREMENTS:

Primary outcome was incident-adjudicated dementia, based on 3MS, hospital records and dementia drugs. Secondary outcome was change in 3MS. Models were adjusted for age, sex, race, education and baseline 3MS, and then further for cardiovascular risk factors.

RESULTS:

Among 2558 adults, 85% were euthyroid (TSH 0.45-4.49mIU/L), 2% had subclinical hyperthyroidism with mildly decreased TSH (TSH 0.10-0.44 mIU/L), 1% subclinical hyperthyroidism with suppressed TSH (TSH < 0.10 mIU/L with normal free thyroxine [FT4]) and 12% subclinical hypothyroidism (TSH 4.50-19.99 mIU/L with normal FT4). Over 9 years, 22% developed dementia. Compared to euthyroidism, risk of dementia was higher in participants with subclinical hyperthyroidism with suppressed TSH (HR 2.38, 95% CI = 1.13;5.04), while we found no significant association in those with mildly decreased TSH (HR 0.79, 95% CI = 0.45;1.38) or with subclinical hypothyroidism (HR 0.91, 95% CI = 0.70;1.19). Participants with subclinical hyperthyroidism with suppressed TSH had a larger decline in 3MS (-3.89, 95% CI = -7.62; -0.15).

CONCLUSIONS:

Among older adults, subclinical hyperthyroidism with a TSH < 0.10 mIU/L was associated with a higher risk of dementia and a larger cognitive decline, while subclinical hyperthyroidism with mildly decreased TSH or subclinical hypothyroidism were not.

KEYWORDS:

cognitive ageing; cognitive decline; dementia; thyroid dysfunction

PMID:
28850708
PMCID:
PMC5658241
[Available on 2018-11-01]
DOI:
10.1111/cen.13458
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center