Hello and thanks for using HCM. I have read your question and understand your concerns. Since there is decrease in mentation in a period of five years, even if this doesn t mean that psychometric tests were positive, is better to take precautions to prevent dementia, because heredity is an important factor. Prevention measures include evaluation and treatment of heart and vessels conditions such high blood pressure, high cholesterol, diabetes. Lifestyle changes that include avoiding smoking and drinking ( if any), exercise continuously, and diet modifications such less red meat, more vegetables, fish, fruits, whole grains etc. Staying socially connected and active also needed as a preventive measure. An important point is prevention of head trauma, because of strong relationship between head trauma and future Alzheimer s. Medical follow up is of paramount value also. Hope you found the answer helpful. Take care.