Memory and Hashimoto’s thyroiditis under levothyroxine treatment: is there a placebo or nocebo effect?

摘要

According to numerous studies, chronic autoimmune Hashimoto’s thyroiditis (HT) is the most common reported cause of hypothyroidism, which is considered to have detrimental effects on the brain, and consequently on one of the most important cognitive functions, namely memory; yet some research suggests that treatment of hypothyroidism, resulting in a return to euthyroidism in HT, may be associated with definite recovery of overall neurocognitive functioning [1]. Although healthy euthyroid middle-aged women, with higher levels of free triidothyronine (T3) and thyroglobulin antibodies (Anti-TG) levels, within the normal range, showed slower cognitive performance and more errors on neuropsychological tests of executive function [2], no research has not confirmed that euthyroidism under synthetic levothyroxine (LT4) treatment leads to serious neuropsychological deficits (e.g. in immediate recall, delayed recall, verbal learning, inhibitory efficiency, information processing speed, or attention switching) [3]. In contrast, other researchers claim that neurocognitive functioning and psychological well-being may not be completely restored in patients with hypothyroidism despite LT4 treatment [1], thus rendering conclusions on HT euthyroid overall cognitive function rather controversial.