In a study, researchers from the Netherlands investigated this. They published their findings in the October 2011 issue of the European Journal of Endocrinology in the article “Endogenous subclinical thyroid disorders, physical and cognitive function, depression, and mortality in older individuals.”
The study used a population-based, prospective cohort, which was obtained from the Longitudinal Aging Study Amsterdam.
Thyroid-stimulating hormone (TSH) and—in some cases—thyroxine and triiodothyronine levels were measured in patients who were 65 years old or older.
Study participants were classified according to clinical categories of thyroid function. Participants who had overt thyroid disease or those who took thyroid medication were excluded from the study, which left 1,219 participants for analysis.
For the purposes of this study, outcome measures were:
The research team found that 64 study participants (5.3%) had subclinical hypothyroidism and 34 participants (2.8%) had subclinical hyperthyroidism.
Investigators noted that when compared with euthyroidism (n=1,121), subclinical hypothyroidism and subclinical hyperthyroidism were not significantly associated with depression or physical or cognitive impairment.
However, study participants who had subclinical hypothyroidism were less likely to report that they had more than one activity limitation (odds ratio: 0.44; 95% confidence interval [CI]: 0.22 to 0.86).
After a median follow-up of 10.7 years, 601 patients who participated in the study had died.
Both subclinical hypothyroidism and subclinical hyperthyroidism were not associated with an increase in mortality risk (subclinical hypothyroidism hazard ratio: 0.89; 95% CI: 0.59 to 1.35; and subclinical hyperthyroidism hazard ratio: 0.69; 95% CI: 0.40 to 1.20).
Researchers indicated that this study does not support that subclinical thyroid disorders are linked with an increased risk of depression, impairment of physical or cognitive function, or mortality in an older adult population.