Alzheimer’s disease (AD) is a terrible disease. Initial clinic signs and symptoms vary. Early symptoms are often chalked up to aging or stress. The most common early symptom is trouble remembering recent events. As AD advances, symptoms can include confusion, language problems, irritability, aggression, mood swings, and loss of memory for remote events. As the patient worsens they often withdraw from family and can’t recognize their own relatives. As the brain deteriorates, bodily functions are lost, leading to death.
In the year 2000 in the United States, AD prevalence was estimated to be almost 2% in the 65–74 age group, with the rate increasing to 19% in the 75–84 group and increasing up to 42% in the older than 84 group. It is often said that if you live long enough, you will get AD. To my knowledge, no studies have looked at latitude and AD, nor have any looked to see how common it is around the equator. It is more common among African Americans.