Table 1. Possible mechanisms causing dementia in thyroid dysfunction.

AβPP: amyloid-beta protein precursor

Possible mechanisms causing dementia in thyroid dysfunction

Low thyroid hormones increasing AβPP expression and consequently, amyloid-β peptide and amyloid-β levels

Reduced degradation and clearance of amyloid-beta plaques from brain, due to the up-regulation of neuroserpin by activation of thyroid hormone response

Oxidative stress and decreased antioxidant metabolites in hyperthyroid patients causing degenerative changes in the brain and neuronal death

Thyroid dysfunction increasing vascular risk factors which lead to alzheimer’s disease

Higher total tau protein levels seen in hyperthyroid patients