Aging vs. Alzheimer's

By Melissa Murphy

There are still many questions surrounding what causes Alzheimer's disease and what determines who gets it. Does everyone who lives long enough eventually develop Alzheimer's? Is it a normal part of aging? Despite extensive research over the last several years, experts are still in the dark concerning many aspects of this dreaded disease.

What Scientists Do Know About Alzheimer's

Despite the fact that much is still left to learn about Alzheimer's disease, most experts concur that the disease is related to aging, but the good news is that it is not a part of the normal aging process. Alzheimer's is not the inevitable consequence of living to a ripe, old age. Researchers who have studied centenarians can confirm that, although aging brains and Alzheimer's brains have certain similarities, not everybody is destined to develop the disease.

The Similarities between Normal Aging and Alzheimer's

Both non-diseased aging brains and those diagnosed with Alzheimer's disease have free radical damage. The difference is that people who suffer from Alzheimer's disease have extensive and distinctive patterns of damage to the neurons in the brain which causes a significant decline in memory and other cognitive functions. In aged individuals with non-diseased brains this damage is also present, although it is not nearly as pronounced as those with Alzheimer's. Harvard researchers note that Alzheimer's disease may be exacerbated by a number of factors including genetic components, immune system deficiencies, diet, and environmental pollutants.

Who Gets Alzheimer's disease?

According to statistics, about 4% of people between the ages of 65 and 74 will develop Alzheimer's. That figure increases to an astonishing 50% for people over the age of 85. Equally as astonishing is that when human brains of people between the ages of 60 to 100 with no apparent cognitive decline were studied, researchers found that there was no significant loss of neurons that was due to the aging process itself. The bottom line seems to be that both diseased and non-diseased brains show signs of free radical damage, but some brains find ways to compensate for the damage by developing new neuro-pathways that successfully close the gaps in brain circuitry, resulting in normal cognitive functioning.

We now know that the human brain possesses a level of plasticity that scientists of yesteryear never could have dreamed of, however, until very recently mainstream science continued to cling to the idea that an adult human brain was incapable of developing new brain cells. They thought that when brain cells were lost, they could not be replaced. That idea has since gone the way of the dinosaurs. In 1996, it was proved that new neurons were being generated in the hippocampus region of animal brains - even well into old age. This finding was soon followed by the confirmation that brain cells were, indeed, regenerating in humans as well. An innovative age of brain research is well underway and is ushering in new ways of thinking about the human brain and giving scientists a fresh perspective in the fight against Alzheimer's disease.

References:

Canacchi, B., et al. Cognitive decline in the elderly: a double-blind, placebo-controlled multicenter study on efficacy of phosphatidylserine administration. Aging Clin Exp Res; 5:123-133, 1993

Dai, j., et al. Recovery of axonal transport in "dead" neurons. Lancet; 351(9101):499-500, 1998.

Davis, D.G., et al. Alzheimer neuropathologic alterations in aged cognitively normal subjects. J neuropahol exp neurol; 58(4):376-88, 1999.

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