Answer:
There are several factors that can contribute to significant brain loss by age 65, including genetic predisposition, medical conditions, and lifestyle factors. However, individuals with a history of heavy alcohol consumption, chronic stress, and traumatic brain injury are considered to be at a higher risk for significant brain loss by age 65. Additionally, individuals with untreated high blood pressure, high cholesterol, and diabetes may also be at increased risk. It is important to note that brain loss is a natural part of the aging process, but certain lifestyle choices and medical conditions can accelerate the rate of decline.