Endocrine Abstracts

In the present study, we investigated neural alterations in newly diagnosed patients with mild hypothyroidism due to Hashimoto’s thyroiditis alongside mood and cognition as well as changes with treatment initiation. Animal studies and first studies of human brain metabolism using radioactive tracers suggest neural involvement in affective and cognitive symptoms of hypothyroidism. Here, we introduce non-invasive magnetic resonance imaging (MRI) techniques that allow the analysis of both brain structure and functional connectivity between brain regions and may thus help identifying neural correlates of hypothyroid symptoms.

Nine patients and nine healthy matched control subjects (mean age 42±5 vs 38±8 years; one male each) underwent structural and resting-state functional 3T MRI scanning and comprehensive neuropsychological testing before and 3 months after treatment initiation. Voxel-based-morphometry was used to investigate grey matter density and resting-state functional MRI to analyse the connectivity of brain regions known to be involved in hypothyroidism such as the hippocampus, the amygdala and the anterior cingulate cortex. Treatment restored thyroid hormone levels to the reference range, though the overall effect was small (mean±S.D. TSH (mU/l): pre 6.1±1.2; post 3.4±1.2). Patients reported significantly higher symptom load, reduced well-being and mental health compared to the control group before but not after treatment initiation. We did not find cognitive impairment or neural alterations even before treatment and no change with treatment. The observed mood alterations could not be related to brain structure or function. The attempt to relate initial treatment effects in mild hypothyroidism to changes in brain structure and function did not produce positive results. Given the small sample size and the mildness of the hypothyroidism, we cannot exclude a false negative finding regarding cognition and brain data. We still want to share the data to avoid publication bias and have thus made them available here for use in meta-analyses: http://neurovault.org/collections/169/.