December 11, 2003
Stress From Neophobia May Shorten Life Expectancy

Fear of the new shortens life expectancy in rats.

Now researchers have found that neophobic rats die an average of three months younger than their outgoing brothers — equivalent to ten years shaved off a human life1.

Personality traits probably affect life expectancy.

"It shows we need to consider personality traits and behavioural styles when trying to understand physiological mechanisms of health," says Sonia Cavigelli at the University of Chicago, Illinois, who conducted the study with her colleague Martha McClintock.

But way back in our evolutionary past the kinds of personality traits that might make us more depressed or anxious or stressed were probably evolutionarily adaptive for some of our ancestors.

Neophobic rats do not recovery as quickly from a fright.

"It was the going up and not coming down as fast," McClintock says. She likens it to hearing a sound in the middle of the night. Some people will wait and listen for a few minutes then fall back asleep. Others will worry for hours, alert for another noise.

"What we showed is that they recovered from that response more slowly," she adds. "We correlated that [with] an early death. It really suggests that we need to look at the effect of having a slow recovery to a stressor to being neophobic, where it happens over and over again on a daily basis."

Then do people who fear the new and unknown need to have their personalities modified in order to live longer? It might be possible to block the physiological response without impacting the emotional response. The reason is pretty simple: it may some day to possible to selectively suppress the stress response in the body when the brain becomes fearful. If the stress response could be suppressed then the more neophobic personalities could probably go through life feeling fear or aversion to new experiences with little resulting damage to their bodies.

The mechanism by which the life of the rats are shortened is probably by fear causing the brain to act on the hypothalamus and other glands to cause them to release stress hormones which in turn cause changes that age the body more rapidly. The changes which shorten life expectancy probably include greater production of immune and inflammation responses. Evidence is accumulating for the role of chronic inflammation in the development of a large variety of diseases. Inflammation may also wear out adult stem cell reservoirs by causing more cell division than would otherwise be the case. So the stem cells more quickly reach their limit in the number of times they can divide and once adult stem cells are no longer available to repair injuries the total amount of damage would accumulate more rapidly.

Still, there is an argument to be made for personality engineering in order to reduce the incidence of neurological disorders. For instance, psychological distress appears to contribute to the development of Alzheimer's Disease.

People who are prone to psychological distress are more likely to develop Alzheimer's disease, research suggests.

Rush University in Chicago found people plagued by negative emotions like depression and anxiety were at double the risk of more laid-back individuals.

But is this higher risk the result of emotional states in the brain acting directly on the brain? Inflammation may play an important role in the development of Alzheimer's. Anti-inflammatory drugs may be able to reduce the level of a peptide that is involved in the formation of amyloid plaques that are characteristic of Alzheimer's.

In a new study, researchers suggest that some anti-inflammatories reduce the levels of a protein fragment (or peptide) associated with Alzheimer's by interfering with two proteins that help manufacture the fragment in the first place. The proteins are called Rho and Rock.

The researchers inhibited Rho and Rock in mutant mice and significantly reduced the levels of the most dangerous peptide found in humans, called amyloid-ί-42. Amyloid peptides form the plaques that are a signature of Alzheimer's disease. The findings are reported in Science.

“The take-home message from this study is that if non-steroidal anti-inflammatory drugs are effective, they may be effective through this [Rho-Rock] mechanism,” says Steven M. Paul of Lilly Research Laboratories in Indianapolis, who led the study. “The mechanism may be unrelated to what these drugs do as anti-inflammatories.”

Now at this point you might be thinking the immortal lyric "Don't worry, be happy". But life is never that simple. A little stress may be good for you

EVANSTON, Ill. -- We've often heard that red wine and dark chocolate in moderation can be good for you. Now it appears that a little stress may be beneficial, too.

Northwestern University scientists have shown that elevated levels of special protective proteins that respond to stress in a cell (known as molecular chaperones) promote longevity. Acute stress triggers a cascading reaction inside cells that results in the repair or elimination of misfolded proteins, prolonging life by preventing or delaying cell damage.

The findings are published online today (Dec. 10) by Molecular Biology of the Cell, a publication of the American Society for Cell Biology. The article will appear in print in the journal's February 2004 issue.

"Sustained stress definitely is not good for you, but it appears that an occasional burst of stress or low levels of stress can be very protective," said Richard I. Morimoto, John Evans Professor of Biology, who co-authored the paper with lead author James F. Morley, a graduate student in Morimoto's lab. "Brief exposure to environmental and physiological stress has long-term benefits to the cell because it unleashes a great number of molecular chaperones that capture all kinds of damaged and misfolded proteins."

Update: UCLA researchers have found that shy people infected with HIV do more poorly on anti-retroviral drug treatment than more outgoing and extroverted people. (or here)

"We found a strong linear relationship between personality and HIV replication rate in the body," Cole said. "Shy people with high stress responses possessed higher viral loads."

The researchers were surprised to find that the antiretroviral drugs barely made a dent in the shy patients' disease. Instead of showing lower viral loads, the immune systems of introverted subjects replicated the virus between 10 to 100 times as fast as in other patients.

"Shy patients on drug therapy didn't experience even a 10-fold drop in their viral load," said Naliboff, co-director of the UCLA Center for Neurovisceral Sciences and Women's Health. "Doctors classify that as a treatment failure. The drugs should shrink HIV replication by at least 100‑fold."

"Our findings suggest that high nervous system activity helps the virus continue replicating," Cole said. "Patients with high-stress personalities continued to lose T-cells — even on the best drug therapy available. Stress sabotages their battle against this lethal disease."

"It looks as though sensitive people are simply wired to respond to stress more strongly than resilient people," Naliboff said. "How someone reacts to stress seems to be more important than the stress itself in explaining why one person gets sick and one person doesn't."

"This heightened stress response is the equivalent of waves striking a stone on the beach," Cole said. "One wave won't do much damage. But the constant pounding of waves eventually grinds that stone to sand. That's how continual stress response wears down the immune system."

Previously the UCLA team found that the body under stress releases a chemical called norepinephrine that leaves the T-cells open to infection and accelerates HIV replication. The researchers' next step will be to try and change shy persons' physiologic response to stress using drugs that block norepinephrine's impact on T-cells.

"Our current study suggests that the body's production of norepinephrine during stress makes a big difference in people trying to fight off infection," Cole said.

Note the part about how these UCLA researchers are going to try to block the physiological response that follows from the cognitive response to stressful situations. The ability to block the brain's ability to send the body into a stress state would be useful for healthy people as well since it would slow and delay the development of many degenerative diseases associated with aging. The stress response is an evolutionary legacy that has become maladaptive in modern industrial society.

Anger is another stressor that has harmful effects on the body. Anger and the lack of friends are both risk factors for periodontal disease.

If you constantly exhibit anger and are a social hermit, such stressors might put your oral health at risk, according to a study in this month's Journal of the American Dental Association. Results from the study reveal that men who reported being angry on a daily basis had a 43 percent higher risk of developing periodontitis (gum disease) compared with men who reported seldom being angry, wrote the Harvard University researchers. In addition, men who reported having at least one close friend had a 30 percent lower risk of developing periodontitis compared with those who did not.

The study authors cited stress as being associated with poor oral hygiene, increased glucocorticoid secretion that can depress immune function and increased insulin resistance. All of these mechanisms, they wrote, can potentially increase the risk of developing periodontitis.

Stress, whether caused by fear of the unknown, loneliness, anger, or other factors, is bad for your health and for your life expectancy.

Share |      Randall Parker, 2003 December 11 11:02 PM  Aging Studies

Bob Badour said at December 12, 2003 4:40 PM:

At least one of the stress hormones, cortosol, is catabolic. I have little doubt that breaking down tissues shortens life.

Stress effects said at March 7, 2007 4:05 PM:

Yeah, given the unprecedented amount of stress in today's corporate world, with greater demands placed on employees than ever before in the competitive modern economy, I think we might see a reduction in lifespan. Then again, who knows, maybe appropriate medication and diet is capable of reversing the deleterious effects of stress and anxiety? I imagine that copious research is being conducted into these areas of interest.

Aeig said at March 13, 2007 8:18 PM:

Some people reading this may realize their stress-related habits have been poor for some time, and this may stress them out even more! Hehe, I say everyone becomes a car salesman at a young age to get shyness over with to help control stress :P.

Very interesting read!

- Aeig

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