Subclinical hypothyroidism (sHT) is very common in general population, especially in women and older people.
sHT individuals may experience symptoms that resemble those observed in overt hypothyroidism, resulting in impaired
quality of life (QOL). Asymptomatic patients may suffer a reduction in perceived health status due to the awareness
of disease. Cognitive function represents one of the most important domains of the QOL questionnaires. Given the
intrinsic relationship between cognitive status and QOL it is worth to address these topics together, in a systematic review
of the literature. Thus, we reviewed the English scientific literature available on National Library of Medicine
(www.pubmed.com) sine 1980 regarding hypothyroidism, sHT, elderly, L-thyroxine (LT4) therapy, QOL, cognition,
brain. We supplemented the search with records from personal files, textbooks, and relevant articles. The possible link, at molecular
level, between cognition and thyroid failure was also assessed. Conflicting results on the association between sHT and
cognitive and health related QOL impairment are still present, although the most recent, naturalistic studies did not find any
significant relationship. Interestingly, a reduction in health related QOL is frequently reported in patients with thyroid autoimmune
diseases regardless of thyroid dysfunction. We also report most significant patents on the topic.