**2. Clinical symptoms during transient severe hypothyroidism quantified by psychophysical investigations in adult human test persons**

To illustrate some conspicuous effects of thyroid hormone on brain function we studied 6 patients after total thyroidectomy for thyroid carcinoma who had discontinued taking thyroid hormone prior to routine diagnostic 131I- scanning and who thus showed a reproducible degree and duration of hypothyroidism. Symptoms described to occur a few weeks after discontinuation of thyroid hormone therapy are changes in peripheral conduction velocity and in the EEG (15). Furthermore, subjective impairments of the quality of life (38–40) as well as changes in mood (41, 42) and decreases in working memory (43) have been reported.
