Alzheimer’s disease (AD) is currently the sixth leading cause of death among United States’ older adult population. An estimated 5.4 million elderly people suffer from this disease. Among the ten primary causes of death in the United States, Alzheimer’s disease has the biggest sex difference, with a far greater number of women than men dying from this disease. Many studies have been done to explore the medication that could postpone the onset of the disease by just five years, potentially cutting health care costs to Medicare significantly. The medication that has received the greatest attention in the Alzheimer’s disease research domain is hormone therapy (HT).
A recent review published by The North American Menopause Society focused on the clinical studies that have explored the relationship between the critical window hypothesis of hormone therapy and cognition. The critical window hypothesis states that how effective hormone therapy is depends on when the treatment is started with respect to biological age, onset of menopause, or both, with positive results limited to an early start of hormone treatment.
Hormone therapy use is typically initiated early in women who have just started menopause. Taking this into account, the review explored the results from observational studies of women who had ever used hormone therapy and observational studies that focused specifically on the time of initiation of hormone therapy on Alzheimer’s disease and cognitive performance tests.
After the review, the authors found that the observational data showed that hormone therapy generally decreased the risk of Alzheimer’s disease. Three out of three observational studies that specifically explored the timing of initiation in association to Alzheimer’s disease risk each strengthened the evidence for the critical window hypothesis. However, only three out of five observational studies of hormone therapy timing and cognitive performance test showed the same findings. Randomized clinical trials of estrogen therapy in women of younger ages showed evidence supporting the hypothesis.
In conclusion, a definitive trial that can effectively test the critical window hypothesis is not possible at this time. Previous studies have shown supporting evidence for the hypothesis. These findings may be relevant to older women who undergo hormone therapy to treat vasomotor symptoms, hormone therapy is currently not appropriate as a treatment options for cognitive complaints or as a preventative measure for dementia.
Care providers who are responsible for providing quality care to older adult women who reside in long term care facilities such as skilled nursing homes or assisted living facilities should be educated in these types of matters—especially for patients with Alzheimer’s disease. Knowing the risks and benefits of treatment options to alleviate or prevent the onset of common diseases and illnesses of older adults is crucial when developing the best care plan for these vulnerable patients.