Frequency-Specific Alterations of Fractional Amplitude of Low-Frequency Fluctuations in Adult-Onset Hypothyroidism

Abstract Purpose Abnormal spontaneous neuronal activities associated with cognitive deficits and emotional dysfunction were found in hypothyroidism. However, routine method employs a relatively broader range of spontaneous fluctuations and would mingle physiological fluctuations contained in specific frequency. In current study we explored how frequency-specific changes of fractional amplitude of low-frequency fluctuations (fALFF) in hypothyroidism. Methods Fifty-three hypothyroid patients and thirty-nine healthy controls (HCs) underwent clinical variables, neuropsychological assessment, and MRI scans. The fALFF in the routine band, slow-4, and slow-5 bands were analyzed. Additionally, Pearson correlation analysis was performed between fALFF and clinical variables and neuropsychological scores in hypothyroid patients. Results Compared to HCs, within the routine band, patients showed significantly decreased fALFF in left lingual gyrus, middle temporal gyrus (MTG), calcarine cortex, precentral gyrus, and right inferior occipital gyrus; within the slow-5 band, the patients exhibited decreased fALFF in left lingual gyrus, MTG, superior temporal gyrus, postcentral gyrus, and paracentral lobule, and increased fALFF in right middle frontal gyrus and supplementary motor area; Additionally, fALFF in the left lingual gyrus within the routine and slow-5 bands were negatively correlated with thyroid stimulating hormone level. Conclusions We found that fALFF in left lingual gyrus and MTG decreased both in routine and slow-5 bands in hypothyroid patients. These might be potential neuroimaging biomarkers of cerebral impairment in hypothyroid patients. Trial registration ClinicalTials. No:ChiCTR2000028966. Registered 9 January, 2020, https://www.chictr.org.cn