Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2014) 35 OC1.4 | DOI: 10.1530/endoabs.35.OC1.4

ECE2014 Oral Communications Thyroid clinical (5 abstracts)

Consequences of experimental hyperthyroidism on brain structure and function in humans

Anna-Luise Dirk 1 , Anna Goebel 2 , Marcus Heldmann 2 , Alexander Iwen 1 , Georg Brabant 1 & Thomas Münte 2


1Experimental and Clinical Endocrinology, Med Clinic I, University of Lübeck, Germany; 2Department of Neurology, University of Lübeck, Germany.


Objective: Disturbed levels of thyroid hormones are associated with neuropsychiatric disorders, including memory impairments. Even short-term hyperthyroidism may affect properties of the human brain. To investigate the influence of thyroid hormones, we conducted functional neuroimaging. The aim of this study was to evaluate functional changes in working memory performance.

Materials and Methods: Twenty healthy, male, right-handed subjects (age range 21–49 years, median 30 years) in good general health without mood or cognitive disorders and normal thyroid state gave their informed consent to participate. High resolution 3D T1-weighted MRI scans were acquired by 3T MRI from the subjects before and after taking 250 μg L-thyroxin for a period of 8 weeks. Thyroid function was measured and subjectively assessed by questionnaire. For both time points all participants conducted a working memory task (n-back task). Functional analysis was performed using Statistical Parametric Mapping 8 (SPM8).

Results: Despite a lack of significant subjective changes assessed by questionnaire all subjects developed biochemical hyperthyroidism after 8 weeks with a 1.7-fold increase in baseline fT3, a 2.1-fold increase in fT4 levels and suppressed TSH levels. In the hyperthyroid condition the subjects showed slower reaction times, but a higher accuracy in 0-back memory tasks. The more difficult the memory tasks were, the less effect could be seen. Significant differences of task-induced functional activation were found especially in bilateral insulae, bilateral prefrontal cortex, bilateral anterior cingulate cortex and bilateral posteriocerebellum (P<0.05, FWE corrected). When comparing euthyroid and hyperthyroid condition in relation to task-induced activation, differences of activation were found in the right prefrontal cortex, as well as in the right parahippocampal area (P<0.001, uncorrected).

Conclusion: It can be concluded that a short-term intake of thyroid hormones lead to an activation of brain areas associated with working memory.

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