Abstract
We summarize here the studies examining the association between thyroid function and cognitive performance from an aging perspective. The available data suggest that there may be a continuum in which cognitive dysfunction can result from increased or decreased concentrations of thyroid hormones. Clinical and subclinical hypothyroidism as well as hyperthyroidism in middle-aged and elderly adults are both associated with decreased cognitive functioning, especially memory, visuospatial organization, attention, and reaction time. Mild variations of thyroid function, even within normal limits, can have significant consequences for cognitive function in the elderly. Different cognitive deficits possibly related to thyroid failure do not necessarily follow a consistent pattern, and L-thyroxine treatment may not always completely restore normal functioning in patients with hypothyroidism. There is little or no consensus in the literature regarding how thyroid function is associated with cognitive performance in the elderly.