Effect of normalization of an isolated increase in TSH on the neuropsychological profile of patients

BACKGROUND: Isolated TSH increase--"subclinical hypothyreosis" (SH) appears to be comparatively common. Its incidence among women over sixty has been estimated up to 17%. Though SH was assumed to be entirely asymptomatic, recent findings revealed various fine subjective and objective symptoms of the disease. METHODS AND RESULTS: Twenty otherwise healthy female patients with SH diagnosis were examined. Using personality questionnaire MMPI/100 eight different clinical scales and two control scales were evaluated, using Wechsler's memory scale WM-R 5 memory quotients were tested. The group was randomised into a subgroup treated for six month with placebo and a subgroup where thyroxin was administrated and thyroidal test normalised. Psychological testing repeated before and after the treatment, results evaluated using paired t-test. Results indicate that: 1. Patients with SH did not differ in personality features, they only had a higher tendency to the depressive mood, which could be positively influenced by thyroxin (significance at 5% level). 2. Thyroxin treatment brought about improvement of some cognitive parameters of the verbal (p < 0.01), visual (p < 0.05), and general memory (p < 0.01). 3. Results of psychological and cognitive tests correlate better with FT4 than TSH level. CONCLUSIONS: Though SH cannot be associated with changes in personality features, TSH normalisation results in statistically significant improvement of cognitive function--verbal, visual and general memory.