Low TSH levels associated with incident depression among women
Low thyroid-stimulating hormone levels are positively associated with incident depression, particularly among women, and even among euthyroid adults, according to findings published in Clinical Endocrinology.
“The findings reinforce the need to carefully investigate psychiatric disorders in people with subclinical thyroid diseases, during clinical practice,” Ana C. Varella, DSc, of the Clinical and Epidemiological Research Center at the University of Sao Paulo, told Healio. “In addition, not only paying attention to cases of high TSH levels, but also low TSH levels. The findings are particularly interesting because we would expect higher TSH levels to be associated with depression after a period of time; however, this was not the case. In fact, our results showed higher TSH levels to be inversely associated with incident depression.”
Varella and colleagues analyzed baseline TSH and free thyroxine levels from 11,986 participants in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a cohort of adults in civil servant jobs from six Brazilian cities, enrolled between August 2008 and December 2010, who were monitored and evaluated 4 years later (mean age, 52 years; 51.2% women; 92.9% euthyroid; 1.4% with subclinical hyperthyroidism; 5.7% with subclinical hypothyroidism). TSH levels were categorized in quintiles: 0.96 mIU/L or less (quintile 1); 0.97 mIU/L to 1.34 mIU/L (quintile 2); 1.35 mIU/L to 1.78 mIU/L (quintile 3; reference); 1.79 mIU/L to 2.58 mIU/L (quintile 4); and 2.59 mIU/L to 35.5 mIU/L (quintile 5).
Depression diagnoses were performed using the Clinical Interview Schedule-Revised (CIS-R) at baseline and at 4-year-follow-up. Researchers used Poisson regression models to evaluate the association between TSH quintiles at baseline and incident depression, with analyses stratified by sex.
Overall, low TSH levels (first quintile) were associated with incident depression, with an adjusted RR of 1.36 (95% CI, 1.02-1.81). Results persisted with analyses restricted to women (aRR = 1.64; 95% CI, 1.15-2.33), but not for men.
The same results were found when restricting analysis to euthyroid participants, with an aRR of 1.46 (95% CI, 1.08-1.99), also significant for women only (aRR = 1.63; 95% CI, 1.12-2.38).
“No association was found between thyroid dysfunction as a categorical variable and incident depression, for either subclinical hyperthyroidism or subclinical hypothyroidism, even stratifying the analysis by sex,” the researchers wrote.
For more information:
Ana C. Varella, DSc, can be reached at acvarella@gmail.com.
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