(HealthDay News) – There is no association between either clinical or subclinical hypothyroidism and mild cognitive impairment (MCI) in the elderly, according to a study published online Dec. 30 in JAMA Neurology.

Ajay K. Parsaik, MD, from the University of Texas Medical School in Houston, and colleagues analyzed data from 1,904 participants (aged 70–89 years in 2004) who were free of documented dementia. Evaluations included an in-person interview, neurologic evaluation, and neuropsychological testing in order to categorize participants as cognitively normal, having MCI, or having dementia. Linked medical records were used to determine clinical or subclinical hypothyroidism.

The researchers found that the frequency of MCI was 16% in 1,450 individuals with normal thyroid function, 17% in 313 persons with clinical hypothyroidism, and 18% in 141 individuals with subclinical hypothyroidism. After adjusting for age, educational level, sex, and other clinical conditions, there was no significant association between clinical or subclinical hypothyroidism and MCI (odds ratios, 0.99 [95% confidence interval, 0.66–1.48] and 0.88 [0.38–2.03], respectively). There was no effect on the odds of MCI with clinical and subclinical hypothyroidism among either men or women.

“In this population-based cohort of elderly people, neither clinical nor subclinical hypothyroidism was associated with MCI,” the authors write. “Our findings need to be validated in a separate setting using the published criteria for MCI and confirmed in a longitudinal study.”

One author disclosed financial ties to the pharmaceutical industry.

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