Cognitive function and quality of life in mild thyroid hormone deficiency

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.