Thyroid-stimulating hormone and cognitive impairment in non-depressed non-demented multiethnic middle-aged and older US adults: Assessing sex-specific risk prediction

Background

Understanding the particularities of thyroid-cognition interactions in older adults is crucial in assessing the risks and evaluating therapeutic options.

Methods

Cross-sectional analyses where participants from Alzheimer’s Disease Neuroimaging Initiative (ADNI) with mild cognitive impairment (MCI) and healthy controls (HC), with complete neurocognitive tests, thyroid stimulating hormone (TSH) <10 µIU/mL, and geriatric depression scale (GDS) <5, were eligible. Linear and logistic regression models, including testing for non-linearity, were performed. Sex strata were explored.

Results

Of the total 1845 multiethnic US-participants, with a median age of 73 (IQR: 68, 78); 887 (48 %) were females, and 1056 (57 %) had MCI. The median TSH level was 1.70 µIU/mL (IQR: 1.15, 2.40); significantly lower in MCI than HC (1.66 vs. 1.74 µIU/mL, p-value=0.02). There was a significant association between TSH and overall cognition only in males (adj. ß_Males=-0.40[-0.74, -0.07], p-value=0.019). The odds of being diagnosed with MCI at baseline decreased with higher TSH levels in the total study population (adj. OR_Total=0.87[0.79, 0.95], p-value=0.002) and in males (adj. OR_Males=0.80[0.70, 0.92], p-value=0.001).

Conclusions

There was a sex-specific, statistically significant association between TSH levels and cognition in multiethnic middle-aged and older ADNI adults. Lower TSH levels and worse global cognition were statistically associated only in males. To precisely delineate the chronological onset of these disorders, longitudinal clinical studies are needed.