Thyroid status in senile dementia of the Alzheimer type (SDAT)

Thyroid function was investigated in a group of 21 patients with severe senile dementia of the Alzheimer type (SDAT) and in a group of 17 age and sex matched normal controls. Free thyroid hormone levels (triiodothyronine (T3) and thyroxine (T4) were measured, as were also the thyrotrophin (TSH), prolactin (PRL) and growth hormone (GH) responses to thyrotrophin releasing hormone (TRH)). When compared to controls, patients demonstrated a significantly lower free T3 value (but not free T4), a blunted TSH response to TRH, slightly elevated basal PRL and GH values and a small GH response to TRH. However, all differences were small in biological terms and were within the laboratory's normal range. This emphasizes the relative normality of neuroendocrine function, particularly thyroid status, in SDAT.