Thursday, May 24, 2012

The ultimate cause of death by Jerry Brainum

For years, I've read and heard about old people dying from "old age." That never made any sense to me, after all, you have to die from something, and dying from old age wasn't exactly a specific cause of death. Yet, there was no doubt that old people die, so something must be killing them. In most cases, the main killers are either cardiovascular disease or cancer. Both of them rise with age as the body's defenses gradually ebb with time. But then you have the cases of those people who manage to outwit the odds, and make it to 100 or over. Gerontologists, or those who study the science of aging, have analyzed such people, and found that they have a series of genetic anomalies that appear to protect them against the main killers, cardiovascular disease and cancer. They stay remarkable healthy until they reach about 105, then their health suddenly declines, and most die soon after reaching that age.The statistics show that 30% of them die from pneumonia,which in them is considered a failure of the immune system, since the same type of pneumonia would rarely kill a younger person. Fitness guru, Jack Lalanne made it to 95 in good health, but then succumbed to pneumonia. Dying from pneumonia is hardly "dying of old age."
     But what about the other 70% of very old people; what kills them? It's a salient question, since some scientists, such as the late Roy Walford, suggested that humans should live to at least 140. In reality, however, the oldest confirmed person on record was a French woman named Jean Calment, who died in 1997 at age 122. She was still drinking and smoking over the age of 100, strongly suggesting that her longevity was based on a lucky draw of the genetic cards.But again, what is the primary cause of death in old people that is often referred to as "dying of old age." The answer is systemic amyloidosis.
     Specifically, it has to do with transthyretin amyloidosis (TA). Transthyretin is normally good stuff. It's a protein that transports both thyroid hormones and vitamin A in the blood. But when the gene for transthyretin gets mutated, the protein that comprises it, known as amyloid, become misfolded and sticky. They tend to aggregate into long fibers that can accumulate inside blood vessels and other tissues in the body. They can damage organs, nerves, and heart tissue. In the brain, a form of amyloid called beta-amyloid is thought to be the primary cause of Alzheimer's disease.Beta-amyloid tends to form gummy sticky tendrils that interfere and eventually destroy nerve function. While there are several types of amyloid diseases that result from genetic mistakes, the type that affects older folks is known as senile systemic amyloidosis. Many cases of heart failure are actually caused by a build-up of amyloid protein in the heart muscle. There are about 27 proteins linked to amyloid formation. In the very old people, the build-up of amyloid causes death by clogging blood vessels, just as rust clogs old pipes. What isn't fully established is whether amyloidosis is a normal part of aging, or a pathological process.
    But what is known is that the oldest of the old die from the effects of excess amyloid in their bodies, which chokes off their organ function. Ironically., most of these people never get the most common amyloid-based disease, Alzheimer's, but instead die from the build-up of amyloid in their bodies. Their brain remains intact and normal. There are a number of drugs known to prevent the accumulation of excess amyloid in the body. The question now is whether supplying these drugs to very old people will prevent the most common immediate cause of death in people of advanced age, excess amyloid accumulation. If you could prevent such accumulation safely, would that extend lifespan to 140 or more? That is a question that remains to be answered.
    Update: a new drug has been introduced called tafamidis(Vyndaqel), which specifically targets transthyretin amyloidosis. It will be interesting to see if this drug is given to older people, and if it extends their life.
©,2012, Jerry Brainum.Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
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