In adults with subclinical hypothyroidism (increased TSH and normal fT4), is the administration of thyroxine supplementation capable to improve cognitive function? In order to answer this question, an English trial has been performed where 94 subjects over 64 years of age with subclinical hypothyroidism have been treated with thyroxine (up to TSH normalization) or placebo. At enrolment, the average level of TSH was 6.6 mU/l and the subjects have been identified through screening and not according to clinical assessments. Cognitive tests have been performed at the beginning of the trial, after 6 months and after one year. Score resulted not different between treated subjects and controls, either at the beginning or after 6 or 12 months. TSH levels had become normal again after 6 months in 85% of participants treated with thyroxine; the fact that in controls treated with placebo TSH spontaneously became normal again after 12 months in 50% of patients was interesting too.
In elderly with subclinical hypothyroidism, the administration of thyroxine obtains no cognitive improvements. Besides, TSH tends to become normal again spontaneously in half of subjects, so a simple watchful waiting and annual monitoring are sufficient to manage this kind of patients.
