Preliminary study of the relationship between thyroid status and cognitive and neuropsychiatric functioning in euthyroid patients with Alzheimer dementia.

Objective: To investigate whether variations within normal ranges of thyroid functioning are related to cognitive and neuropsychiatric functioning in Alzheimer disease (AD). Background: Mild alterations of thyroid hormone levels, even in the normal range, are associated with changes in mood and cognitive functioning in older, nondemented adults, and lower concentrations of thyroid hormones have been shown to be associated with an increased risk for cognitive decline. Less is known about the relationship between thyroid hormone levels and cognitive and neuropsychiatric dysfunction in AD. Method: Twenty-eight euthyroid patients with AD on donepezil underwent evaluation of thyroid status, including measures of thyroid-stimulating hormone (TSH) and free thyroxine (FT 4 ), and cognitive and neuropsychiatric assessment with the Alzheimer's Disease Assessment Scale, Neuropsychiatric Inventory, and Visual Analog Mood Scales. Results: Correlational analyses indicated statistically significant associations between FT 4 concentrations and self-reported feelings of fear and fatigue. Fear and fatigue were negatively correlated with FT 4 . There were no significant relationships between thyroid hormones and cognition and other depressive and anxiety symptoms. Conclusions: Results of this preliminary study support a relationship between thyroid status and neuropsychiatric symptoms in euthyroid individuals with AD, with lower concentrations of FT 4 associated with fear and fatigue.