Alzheimer’s disease is the most common type of dementia, impacting over 5 million Americans. Although the disease was first described by Dr. Alzheimer in the early 1900s, scientists are still trying to understand its causes. According to the Alzheimer's Association, these are some of today’s leading theories.
In 1900, the average life expectancy in the United States was 47. Today people live well into their 80’s and 90’s. This is good news for most of us and many seniors are enjoying an active, engaged life. However, one downside of a long life is that aging increases your risk for Alzheimer’s disease – 10% of people over 65 have Alzheimer’s disease; 32% of people over 85. Despite these frightening percentages, researchers believe that Alzheimer’s disease is a “normal” part of aging and remain hopeful that we will develop strategies to delay the onset of Alzheimer’s disease or prevent it altogether.
The consensus among researchers is that if you have one or more parent or close family member with Alzheimer’s disease, you are generally considered to be at greater risk for developing the disease. One gene in particular called ApoE4 increases your likelihood of getting Alzheimer’s disease. Like all risk factors, a family history may or may not lead to the development of the disease.
Some lifestyles may be very unfriendly to the brain and increase the risk of Alzheimer’s disease. For example, individuals who sustain concussions or head injury (through sports, work or accidents) have a greater risk of getting Alzheimer’s. Positive lifestyle factors that may reduce the risk of Alzheimer’s includes regular exercise, a healthy diet (with plenty of fruits, vegetables, and whole grains), socialization, minimizing stress, treating depression, lifelong learning (“use it or lose it”) and avoiding tobacco use.
The Alzheimer’s Association has described the suspected links between heart health and brain health. The Association argues that “what is good for the heart is good for the head.” We may not know if a low fat, heart-friendly diet will ultimately prevent Alzheimer’s, but it certainly can prevent stroke, another enemy of the brain.
Plaques and Tangles
Two areas of ongoing research include studying the buildup of plaques and tangles in the brain. Plaque consists of the protein beta amyloid that accumulates in the spaces between nerve cells. Tangles are the twisted fibers of another protein tau (rhymes with “how”) that accumulates inside nerve cells.
These proteins most likely block the ability of the cells to communicate, leading to cell death. This cellular death ravages the brain and causes the progressive symptoms of Alzheimer’s disease.
Much of the research to date on potential medications for Alzheimer’s has looked at ways to prevent the buildup of plaques and tangles in the brain. Unfortunately, there have been a number of very high profile failures and disappointments with promising drugs. Many scientists are now looking at other mechanisms besides attacking plaques and tangles, for example, looking at inflammation in the brain as a possible trigger for Alzheimer’s disease.
Within the field of Alzheimer’s research, there is much optimism, but also a sobering recognition that there is still much to be accomplished. The good news is that our field of knowledge about Alzheimer’s disease is expanding rapidly. New tools such as powerful scanners can look inside the brain and now even identify amyloid plaques. There is also a worldwide effort underway with significant coordination of research between scientists and universities.
The Alzheimer’s Association points out that 90% of what we’ve learned about Alzheimer’s disease has been discovered in the last 15 years. Let’s hope that the next 15 years lead to the breakthroughs we need to help Alzheimer’s disease itself become a “distant memory."