Mild Thyrotoxicosis Leads to Brain Perfusion Changes: An Arterial Spin Labelling Study

Area of Science:

• Neuroscience
• Endocrinology
• Cognitive Psychology

Background:

• Thyroid hormones influence brain structure, function, and cognition, including memory.
• The specific effects of thyroid hormones on brain perfusion and their link to cognitive performance remain largely unexplored.
• Cerebral blood flow is a potential indicator of neural activity, particularly in memory-associated brain regions.

Purpose of the Study:

• To investigate the impact of short-term experimental hyperthyroidism on brain perfusion in healthy individuals.
• To determine if observed changes in brain perfusion correlate with cognitive performance, specifically memory.
• To explore the role of the cerebellum in thyroid hormone-mediated cognitive modulation.

Main Methods:

• Arterial Spin Labelling (ASL) MRI was used to measure brain perfusion in 29 healthy men.
• Participants underwent ASL measurements before and after an 8-week period of ingesting thyroid hormones.
• Memory performance was assessed using psychological tests, including the Auditory Verbal Learning Task (AVLT/VLMT), and correlated with ASL findings.

Main Results:

• Experimental hyperthyroidism led to increased brain perfusion in the posterior cerebellum and regions connected to cognitive control and visual cortex networks.
• These perfusion increases were positively correlated with improvements in performance on the AVLT/VLMT memory task.
• Findings suggest a link between thyroid hormone levels, cerebellar perfusion, and cognitive function.

Conclusions:

• Cerebellar perfusion and function are modulated by thyroid hormones, evidenced by increased perfusion under hyperthyroid conditions.
• The cerebellum's significant number of thyroid hormone receptors likely contributes to this modulation.
• Thyroid hormones may influence cognitive processes, particularly memory, through their effects on cerebellar perfusion and neural activity.