Monday, April 23, 2007


Neuroticism is highly hereditary, sadly, so it is possible that it is some trait associated with neuroticism that causes premature death -- though the adverse effects of worry itself (stress syndrome) could clearly be the problem

While mellowing with age has often been thought to have positive effects, a Purdue University researcher has shown that doing so could also help you live longer. Dan Mroczek (pronounced Mro-ZAK), an associate professor of child development and family studies at Purdue University, compared neurotic and non-neurotic men over time and tied change in the trait with mortality. "We found that neurotic men whose levels dropped over time had a better chance at living longer," Mroczek said. "They seemed to recover from any damage high levels of the trait may have caused. On the flip side, neurotic men whose neuroticism increased over time died much sooner than their peers."

A neurotic personality was defined as a person with the tendency to worry, feel excessive amounts of anxiety or depression and to react to stressful life events more negatively than people with low levels of the trait. Neuroticism levels were measured using a standardized personality test. Results of the study will be published in the print edition of the journal Psychological Science in late May. The study is available online at

In the study, researchers tracked the change in neuroticism levels of 1,663 aging men over a 12-year period. Using the data gathered in the first analysis, researchers calculated the men's mortality risk over an 18-year period using the average levels and rates of change. By the end of the study, half of those men classified as highly neurotic with increasing levels of neuroticism had died while those whose levels decreased or were classified as less neurotic had between a 75 percent and 85 percent survival rate. Even small increases in neuroticism were shown to have negative effects. Participants with as little as a one-unit increase in neuroticism over the course of the study were shown to have a 40 percent higher chance of death than a participant who showed no change.

Data was taken from the Veterans Affairs Normative Aging Study, a longitudinal investigation of aging in men founded at the Boston Veterans Affairs Outpatient Clinic in 1963. In 1988, the beginning of this study, the men ranged in age from 43 to 91.

Mroczek and Avron Spiro, an associate professor of epidemiology at Boston University's School of Public Health, also controlled the data for age, depression levels and both subjective and objective ratings of overall health. "We found that neuroticism levels are a clear indicator of how long one can expect to live," Mroczek said. "The link between mortality and the rate of change in neuroticism is similar to the way we think about change in high blood pressure and risk of heart attack. If you have high blood pressure but make sure to lower it, you are likely to reduce your heart attack risk."

While those who were very neurotic and grew worse over time had a higher death rate, those who were the least neurotic and improved over time did not die at a significantly lower rate. Mroczek said the anomaly could be traced to how these types of attitudes affect personal choices. "It's possible that the key with neuroticism is having just the right amount," Mroczek said. "If you are too laid back, you may not be taking your health seriously enough. These folks might be engaging in more risky behaviors like smoking or drinking to excess because they don't believe anything bad will happen to them."

Mroczek, a member of Purdue's Center on Aging and the Life Course, said he sees a future in which doctors and other health practitioners include some form of personality assessments with routine medical screenings. Learning to deal with some of the potentially negative aspects of human personalities in a positive way could become part of a balanced and healthy lifestyle. "For example, very neurotic people can work toward dealing better with stress," he said. "They can seek therapy, take up yoga, schedule daily walks to help themselves unwind, listen to calming music or even meditate."

While participants in the study were male and more than 90 percent Caucasian, Mroczek said there is little reason to believe that results for women or other ethnicities would show vastly different results. "You can find the full range of personalities in any ethnic or gender group," Mroczek said. "There are those who are laid back and then there are those who worry, who react very poorly to stress, who are always on edge."

Mroczek will begin testing later this year to determine why higher levels of neuroticism increase mortality. He plans a study which tests cortisol levels in neurotic men to determine if they have higher levels of the damaging stress hormone that could contribute to early death. Other possible contributing factors might include unhealthy coping techniques, such as overeating or drinking to excess.

This study was supported by grants from the National Institute on Aging and by the Clinical Sciences Research and Development Service of the U.S. Department of Veterans Affairs. The VA Normative Aging Study is supported by the Cooperative Studies Program/ERIC of the U.S. Department of Veterans Affairs and is a research component of the Massachusetts Veterans Epidemiology Research and Information Center.


Obesity: A Conjecture

From David Friedman. Also see his site for some interesting comments

Obesity is a current hot issue, problem, crisis ... . One reason is that it is a real problem. Another, I suspect, is that it provides people who want governments to do things with a new argument.

My evidence for that conjecture is how much of the talk about obesity focuses on the evils of marketers cleverly manipulating people into eating junk food. While sellers of junk food do, of course, advertise their products, so do sellers of diet soda, exercise equipment, metrecal and health foods. I understand why people concerned about obesity might see the regulation of advertising as a potentially useful tool--it is at least more likely to be politically viable than an attempt to ban hamburgers and french fries from the American diet. But I do not see marketing as a plausible explanation for the increasing frequency of obesity. It seems particularly implausible given that the increase is not limited to rich countries such as the U.S.; I doubt the consumption patterns of people in India or China are much influenced by advertising.

My alternative explanation for obesity is straightforward. Humans evolved in an environment where food was costly, fat scarce, sweetness a useful signal that fruit was ripe. We are designed by evolution to put on weight when we can as a precaution against future famines and to favor fat and sugar when we can get them. In a world where food is inexpensive and plentiful we are inclined to overeat, in particular to eat more fat and sugar than is good for us.

The obvious explanation of the increase in obesity is that real incomes around the world have been trending up for decades. Now poor people in the U.S., and increasingly in poorer parts of the world, can afford to eat all the calories they want. Since all the calories they want represents more than what they require, the result is that they get fat.

There is one problem with this explanation. According to the figures I have seen, in the U.S. obesity is less common in high income groups than in low income groups. The richer you are, the less your diet is constrained by cost, so we would expect higher income groups to be at least as obese as lower income groups. To explain why they are not I must add one additional factor: Time lags in adjusting behavior and social norms to changed circumstances.

Suppose you are part of a population where food has been costly, where people engage in a lot of physical labor, and so where the problem is getting enough to eat, not avoiding too much. You, and those around you, have adapted their behavior to that environment.

Now things change; food gets cheap, wages go up, almost everyone can afford to eat as much as he wants. For a while, perhaps a generation or two, people follow the old patterns in the new circumstances; the result is that many of them end up fat. Over time, although the hardwired elements of behavior do not change--evolution is slow--the cultural elements do. Instead of demonstrating how wealthy and generous you are by urging your guests to have a second and third helping of dinner, you do it by providing them smaller amounts of particularly tasty, sophisticated, or expensive dishes. Instead of making a point of avoiding physical exertion when you can, you enter the Boston Marathon. Eventually you and those around you have adapted your behavior, although not your hardwired tastes, to the new environment.

Well off people in developed societies have been able to afford second and third helpings at every meal for a long time. Hence, if my argument is right, they have had time to adapt to a world of plenty. For poor people, being able to eat all they want of more or less what they want is a newer thing, so they are still following the old ways--the pattern of the traditional Jewish (or Italian) mother who insists that her guests have a little more of this and that before they end their meal. Hence, if my conjecture is correct, greater obesity among the poor reflects the lag in adapting to circumstances that are relatively new for them. The rich have had time to adjust.

One implication of this is that, at some point in the past, richer people should have been more often obese than poorer--back when the rich were no longer constrained by the availability of food but the poor still were. That fits my casual impression, but I have no actual data to support it.


Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.