Expert: Mary Gordon - 2/5/2008

Question
If Alzheimer is not part of the normal aging process, why is it occurring so frequently amongst older adults?

Answer
Hi Cynthia, there are many causes of dementia in the elderly. Alzheimer's disease is just one of them. The main risk factor for all types of dementia is age. About 3% of men and women between the ages of 65 and 74 suffer from dementia, but after age 65, the percentage of people with dementia approximately doubles with every decade of life. The proportion of people aged 85 and older with dementia is between 25 and 35%. It is important to understand that while dementia is seen more in older people, it is not a normal part of aging.

We all are living longer and longer. If you were born in 1900, your life expectancy was 47 years. For a child born in North America now, its now pushing 80. We have more and more people living to greater and greater ages.  In the old days, doctors did not really understand that there were many different types and causes of dementia, which is why they would just say someone was "senile" - which just means old and confused.

The term dementia or senility doesn't tell you what is wrong with a person in terms of what is causing the confusion. They could have Alzheimer's or small strokes, Lewy Body Dementia, Binzwanger's Disease, thyroid problems, Parkinson's Disease, Pick's Disease, Addison's Anemia, Normal Pressure Hydrocephalus, lung disease, and on and on and on. Its really important to know what type of dementia someone has, because some of them can be treated or even reversed, and others can at least by slowed down. All the different causes damage the brain by different mechanisms.

The brain is a very delicate and sensitive organ, and as we age, and become more frail and susceptible to various ailments, it makes complete sense that our brains will be impacted by our health issues - that does not mean that our brains are wearing out, or that the damage is normal or inevitable. For example, a very common cause of dementia from tiny strokes (its called multi-infarct dementia). Risk factors include cardiovascular disease, high blood pressure, high triglycerides, poorly managed diabetes etc. In other words, in the case of strokes, neglecting your overall health can result in a high risk of brain damage.

Many diseases that cause dementia are very poorly understood. At this point, we know what Alzheimer's does to the brain, but we don't know why some people develop it and others not. We don't know what makes it start - how much is genetic, and how much is environmental, or perhaps even an infectious agent.  We don't really understand how a person's lifestyle may alter their risk. Because we don't know how the disease starts, its hard to know how to prevent it.

Lots more research needs to happen - and once we solve the problem of Alzheimer's, there are still dozens and dozens of other diseases that cause brain damage.

Hope this helps.

Mary G.