What is Alzheimer's disease?

Alzheimer's disease was barely a dot on the horizon 50 years ago. But with life expectancies creeping into the mid-seventies or older, we're facing a potential epidemic of dementia. The good news is that scientists are on it; in the past decade, they've identified numerous biological and lifestyle underpinnings of Alzheimer's disease, opening the door to potential preventive strategies.

Advancing age is the greatest risk factor, although an early form of the disease is linked to a genetic mutation. It's not clear what causes Alzheimer's, but it is associated with protein clumps, called amyloid plaques, in the brain, along with "tangles" of brain cells. It's likely that these interfere with processing in the brain.

Got the gene?

Researchers have identified at least 20 genes and genetic abnormalities linked to Alzheimer's disease. The best known is the ApoE gene, which affects the concentration of apolipoprotein Apo(E) in the blood. Apo(E)'s job is to help remove excess cholesterol from the blood and carry it to the liver for processing. While you can be tested for the gene, there's nothing you can do if you have it.

Men who develop diabetes in midlife increase their risk of Alzheimer's disease by 150 percent, according to one study. The risk remained regardless of their blood pressure, cholesterol levels or weight and is probably linked to low levels of insulin. Interestingly, the risk was highest in people who did not have the so-called Alzheimer's gene.

Memory loss, difficulty planning or completing everyday tasks, forgetting simple words or substituting unusual words in writing or speech, getting lost in familiar places, showing poor judgement (such as wearing shorts outside when it's snowing), having difficulty with abstract tasks like adding a column of numbers, putting things in unusual places, mood changes or loss of initiative.

A study of 486 people found that people who have experienced depression severe enough to seek medical help were 2.5 times more likely to develop Alzheimer's than those who never had severe depression. Those whose depression occurred before age 60 had a risk four times higher. One theory is that depression results in the loss of cells in two areas of the brain that also are linked to Alzheimer's disease.

That same daily aspirin that some people take to protect themselves from heart attacks could possibly protect them from Alzheimer's disease, too. In one study, people who took a nonsteroidal anti-inflammatory drug (NSAID) every day for two years or more were 80 percent less likely to develop Alzheimer's than those who took an NSAID less often. Even people who took an NSAID for a month to two years reduced their risk by 17 percent. Talk to your doctor about whether it's a good idea for you to take a daily medication.

People with Down Syndrome all develop Alzheimer's disease by age 40. Now researchers suspect that people without the syndrome who get Alzheimer's may develop a small number of the same chromosomal abnormalities throughout their lifetimes. If true, it could one day mean new options for prevention, diagnosis and treatment.