Background: Over the last decades an increasing body of evidence suggested a possible relationship
between thyroid hormone (TH) and the ageing process, and several efforts have been made to
determine the actual role of TH dynamic during human life. It is still unclear whether the serum level
shift of Thyroid Stimulating Hormone toward higher value, observed during ageing, is a normal adaptive
response associated with senescence or an actual mild thyroid dysfunction. A growing body of evidence
supports the hypothesis of a reset of the hypothalamus-pituitary-thyroid axis in order to contrast the catabolic
status of the ageing process. On the other hand, several meta-analyses showed a direct link between subclinical hypothyroidism
(sHT) and cardiovascular events (both ischemic heart disease and stroke), although mainly in individuals younger
than 65 years. Similarly, a recent meta-analysis documented consistent data on a positive relationship between sHT and cognitive
impairment, but only in individuals younger than 75 years.
Conclusion: The available data suggest a complex relationship between mild thyroid failure and the ageing process as
well as the development and progression of several cardiovascular and neurological diseases. In this paper, we reviewed
the scientific English literature on sHT and the ageing process focusing on experimental evidences related to cognitive
impairment and dementia. Moreover, we focused on new patents of treatments potentially able to improve the care of sHT
patients, especially in the elderly, where treatment drawbacks may have negative impact on the long term outcome.
Keywords: Alzheimer's disease, ageing, cognition, dementia, hypothyroidism, TSH, thyroiditis, thyroid hormone.
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