Thyroid‐stimulating hormone levels implicated in depression

Low thyroid‐stimulating hormone (TSH) levels carry an increased risk of depression, especially in women, a study reports.

The study involved a cohort of middle‐aged adults (mean age, 51.5 years; 51.2 percent female) from the Brazilian Longitudinal Study of Adult Health. All participants had their TSH and free‐thyroxine (FT4) levels measured at baseline. Depression was diagnosed using the Clinical Interview Schedule ‐ Revised (CIS‐R) at baseline and after 4 years of follow‐up.

Poisson regression models revealed that low TSH levels (1st quintile) were associated with an elevated risk of developing depression compared with normal levels (adjusted relative risk [RR], 1.36, 95 percent confidence interval [CI], 1.02–1.81). But this association was only significant among women (adjusted RR, 1.64, 95 percent CI, 1.15–2.33), not men.

The results were consistent when analysis was limited to euthyroid participants, with low TSH levels conferring a risk increase (adjusted RR, 1.46, 95 percent CI, 1.08–1.99). This increase was also meaningful in women only (adjusted RR, 1.63, 95 percent CI, 1.12–2.38).

Conversely, high TSH concentrations appeared to be protective in women.

Thyroid hormones exerting various effects on different processes such as neurogenesis, glial development, myelination, synaptogenesis, and dendritic cell proliferation. As such, the hormones play an important role in normal brain development and function. [BMC Psychiatry 2017;17:327]