Background: Acute hypothyroidism induced by thyroid hormone withdrawal (THW) in patients with thyroid cancer after total thyroidectomy can affect mood and quality of life (QoL). While loss or dysregulation of thyroid hormone (TH) has these well-known behavioral consequences, the effects of TH alterations on brain function are not well understood. Resting state functional connectivity (FC) measured by functional magnetic resonance imaging (fMRI) allows non-invasive evaluation of human brain function. This study therefore examined whether THW affects resting state FC and whether changes in FC correlate with the mood or QoL of the patients with THW status. Methods: Twenty-one patients who had undergone total thyroidectomy for thyroid cancer were recruited. Resting state fMRI scanning of the brain, thyroid function tests, and administration of the 12-Item Short Form Health Survey (SF-12) and the Patient Health Questionnaire-9 (PHQ-9) were performed before and after two weeks of THW. Regional homogeneity (ReHo), one of the measures of resting state FC, was calculated, and each voxel was compared between before and after THW in 19 patients. The ReHo values were extracted from the regions of interest showing within-group differences in ReHo values after THW, and correlations of ReHo values with thyrotropin (TSH) levels, total score of the PHQ-9, and composite scores of the SF-12 were statistically evaluated. Results: Higher ReHo was observed after THW in the brain cortical regions across primary motor and sensory, visual, and association cortices. Among the regions, the ReHo values in the bilateral pre- and postcentral gyri, bilateral middle occipito-temporal cortices, the left precuneus, and the left lingual gyrus showed positive correlations with serum TSH levels after THW. Higher ReHo values in the bilateral pre- and postcentral gyri, the left middle temporo-occipital cortices, and the left ligual gyrus correlated with the lower mental component summary score from the SF-12, while higher ReHo values in the bilateral pre- and postcentral gyri correlated with higher total scores in the PHQ-9. Conclusions: Local brain FC is increased in the acute hypothyroid state. Higher FC correlates with a poorer mental QoL and increased depression in the hypothyroid state.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism