clipped from www.healthnews.com

Thyroid disease, resulting from either low or high thyrotropin levels, has been found to be associated with an increased risk of Alzheimer's disease in women only. Thyrotropin is a hormone that affects thyroid gland function and thyroid hormone levels. When a patient has low levels of the hormone, the condition is known as hypothyroidism, while a patient having high levels is referred to as having hyperthyroidism.

Both conditions are recognized causes of reversible dementia based on previous studies. In fact, routine screening of serum thyrotropin levels is included in evaluation of patients with suspected dementia. However, the effects of a normally functioning thyroid gland on the brain's cognitive abilities have not been made clear. It is not known whether thyroid function affects Alzheimer's or if it is Alzheimer's that affects thyroid function.