Undercooked Meat, At-Risk Personality and How Worry Can Kill You
It was nighttime. A single lab rat entered his experimental outdoor pen and sniffed at a layer of white sand covering the ground. Ahead of him stretched a brick maze, which he soon started exploring. As he walked around, the rat suddenly came upon a strange smell wafting from one of the labyrinth’s corners. He approached with growing curiosity. The scent seemed to pull him in.
What the rat found so alluring that night, as did many of his lab-mates tested in the maze, was cat urine—something that rats normally consider scary and try to avoid. But this rat was different. Just like several other rodents in this particular experiment, he had been infected with a parasite called Toxoplasma gondii. The parasite, as the scientists conducting the trials found out, considerably changed the way the rats behaved. Not only did they display this weird and potentially fatal feline attraction, but they were also more eager to explore the maze than were uninfected rodents.
Humans are no rodents, but T. gondii infection may impact our personality as well. According to some studies, once this tiny parasite makes its home in a person’s body, that person could become more impulsive, sensation-seeking, and aggressive (there are even some initial suggestions that T. gondii increases the risk of having traffic accidents). For a long time, it was believed that personality couldn’t change, that once an extrovert always an extrovert, etc. Yet decades of studies have revealed that personality can indeed be altered, and not just by ingesting parasites but by our own efforts, too. That’s good news, since personality can have a large impact on health and longevity.
There are five main dimensions of personality, known also as the “big five.” You can be either extroverted or introverted, neurotic or emotionally stable, open to experience or closed to it, agreeable or antagonistic, and conscientious or irresponsible. Of course, it’s not all or nothing. You can be very extroverted or just a little bit. One person can be far more conscientious than another. That’s why researchers usually talk about being one or two standard deviations above or below the mean on a certain personality trait. To get a better idea what this might mean, imagine differences in personality as differences in height between people. The contrast between being one or two standard deviations above the mean on, say, introversion, would be like being five feet six inches (168 cm) tall versus six feet tall (183 cm) for an American man.
It’s not just humans that differ in personality—animals do too. Spotted hyenas, rats, chimpanzees, and even trout have distinct personality types. And just like in humans, certain personality profiles seem better for animal longevity. Bolder, more aggressive trout have shorter telomeres in their fins than do fish that tend to behave differently. In people, the connection between personality and health is already so well established that some researchers are calling for interventions for personality types they call “at-risk”—something akin to “do at least 150 minutes a week of moderate-intensity exercise.” In the case of personality, though, it would more likely be “tidy and plan for 150 minutes a week.” That’s because the personality type that appears particularly important for health and longevity is conscientiousness—having a penchant for tidying, planning, and preparing.
Have you ever watched the television classic Gilmore Girls? The show’s main character, Lorelai Gilmore, is charming and sweet but also messy and impulsive. Her diet consists of whatever she suddenly starts craving (“cheeseburger, with a side of cheeseburger, and…a cheeseburger smoothie”) and about ten litres of coffee per day. If Lorelai were a real person, she would be in longevity trouble. A person two standard deviations below the mean in conscientiousness has a 44 percent higher mortality risk compared to someone two standard deviations above the mean. If you could ingest conscientiousness in a pill, it would be a miracle drug—its effects would be much stronger than those of aspirin on reducing heart disease or the Salk vaccine on polio. The positive effects of being organized and industrious are found all across the planet, including Canada, Japan, and Sweden. And if you have a child whose room resembles a constant post-hurricane zone (I have one of those myself), you should be at least as concerned about the effects this mayhem has on your kid’s future health as you may be about their candy intake. Conscientiousness measured in childhood can predict longevity even as far as seven decades into the future.
Part of an explanation for why conscientious people live longer is the fact that they tend to abstain from cheeseburger smoothies, exercise regularly, and follow doctors’ advice. As generally more level-headed people, they choose stable friendships, stay married, succeed at work, and wear seat belts. But even if you control for all of the above and many more health-related behaviours, the strong effects of conscientiousness on longevity still persist. Psychologists studying the topic believe direct biological mechanisms are at play, such as the functioning of the immune and nervous systems, but these mechanisms are still not well understood.
Being low on conscientiousness is particularly dangerous when combined with another personality trait, neuroticism. Take most movie characters played by Woody Allen, and you will get what neuroticism is all about (hypochondria meets constant worrying meets frequent low moods). Although the term is often used lightly, being neurotic is not much fun. People high on this personality trait tend to be anxious and tense, perceiving the world around them as threatening and unsafe. They are often unhappy about the way their lives are unfolding and experience quite a lot of negative emotions, including anger, guilt, and sadness. And yes, they tend to be hypochondriacs, too. If the above seems to describe you, you may be in trouble, since being neurotic can mean even 33 percent higher risk of mortality. Again, these effects are only in small part explained by the propensity of neurotic people to smoke, drink alcohol, or have trouble socializing.
Neuroticism is in fact such a health-wrecker that it may have serious impacts on the economy. In the Netherlands, for instance, the top most neurotic people cost the country over $1.3 billion per year per million inhabitants in health services, out-of-pocket costs, and production losses. And the Netherlands is not even among the most neurotic countries—that would be Greece, followed by Russia (although this particular study compared only thirty-seven nations). The least neurotic country proved to be Israel, with the US, UK, and Canada hovering in the middle. In the US, Pennsylvania, Ohio, and New York have the most neurotic people, while Alaska and Arizona have the least.
One of the reasons why neuroticism may be bad for health could be its connection to worry and rumination. Rumination is dwelling on events and emotions, going over and over the same stuff in your head like a cow chewing its cud. Worry is rumination’s cousin, but while we usually ruminate about things that have already happened, worry precedes potential stressful events—which, by the way, most often don’t materialize. The problem with worriers and ruminators is that their autonomous nervous systems are chronically activated. The stress they experience doesn’t affect them only when the bad stuff actually happens, but also well before it does and long after.
This can lead to unfortunate health consequences. People who worry a lot tend to have fewer natural killer cells—lymphocytes that launch attacks against infections and tumours. What’s more, worry-prone men who have suffered a myocardial infarction are more likely to get unlucky a second time. And if you are awaiting surgery, worrying about it can make recovery tougher. In one study, patients with hernias who fretted about the procedure the most ended with lower levels of immune cells at the wound site and greater pain. They also took longer to get better.
Just as low conscientiousness and high neuroticism increase the risk of dying prematurely, extraversion seems to lower it—although the links between this personality type and longevity are less well established. Extraversion is associated with about a 21 to 24 percent lower risk of mortality—more or less as much as the Mediterranean diet—but about half of the effect is explained by the extroverts’ propensity to socialize (good for h
ealth) and exercise (also good for health).
There used to be one more personality type famously linked with health, and with cardiovascular health in particular—the so-called type A personality. You know the sort: constantly looking at their watch, always stressed, irritable, obsessed with work. And yet I’m saying “used to be” and “so-called” because research on the type A personality is passé. Since the initial hype in the 1950s and 1960s, follow-up studies haven’t confirmed the effects of the type A personality on heart attacks or clogged arteries. There may have been a good reason for this. In recent years, it came to light that the tobacco industry had been happily funding epidemiological studies on type A behaviours—for example by paying key researchers in the field. Such investments made perfect sense for them. Show that it’s not the clouds of inhaled smoke that cause heart disease but instead impatience and workaholism, and you are all set. For the tobacco industry, the type A personality made for a great cardiovascular scapegoat.
However, one ingredient of the type A personality has made a comeback (and no, the tobacco industry is not paying for the research): hostility. If you ever find yourself being cynical, mistrusting others, believing everyone around you is selfish, and responding to stress with aggression—well, don’t. Apart from being hard on other people and alienating them, it’s bad for your heart. It can cause problems with your triglycerides, your glucose levels, and your insulin resistance. Such behaviours, bunched by psychologists into something they call “hostility,” are associated with an increased risk of cardiovascular events—basically, your heart giving up on you. And when it comes to anger not befitting ladies, it looks like grandma may have been right after all, albeit for different reasons than she might have thought. Studies show that hostility is particularly detrimental to women, messing with the inflammatory processes in their bodies, which in turn may lead to cardiovascular disease.
While the type A personality is no longer on the research agenda, there is a new kid on the block: the type D personality. The “D” stands for “distressed,” as in: experiencing a lot of negative emotions such as anger, irritability, sadness, and fear, while being unwilling or unable to share these emotions with others to get some relief. Type Ds worry. They get irritated. They feel blue—a lot. As a result, their bodies age faster. They have shorter telomeres, and their inflammatory proteins are as elevated as if they were ten years older than they really are. Type Ds are also prone to having something called “soft” or “vulnerable” plaque, which is a perfect recipe for a heart attack. As opposed to the regular, stable kind of plaque that can clog your arteries, the lipid core of vulnerable plaque is covered only by a thin, fibrous cap—a bit like a garbage bin secured only with foil instead of a sturdy lid. If things go bad, that fibrous cap can break suddenly and erupt like a tiny volcano, with all the accumulated junk suddenly spilling into your artery, causing a heart attack. In a way, this scenario can be more dangerous than the slow buildup of regular plaque, so the fact that type Ds have a 2.5 times increased chance of such volcano-like plaque rupture is a serious matter. They are also almost four times more likely to die than other patients with coronary heart disease. For these very reasons, having a type D personality is now considered a cardiovascular risk factor by the European Cardiovascular Prevention Guidelines.
All that said, what if you are a child of a Lorelai Gilmore type and a Woody Allen type? A neurotic, disorganized pessimist? Other than gorging yourself on undercooked meat or digging through cat feces to get infected with a personality-changing toxoplasmosis parasite, can you somehow alter your nature? The good news is that it can indeed be done, no kitty poop involved. One way to change your personality is to simply…wait. Human nature tends to shift with age toward less neurotic, less extroverted, and less open to experience but more agreeable. Conscientiousness is more tricky—first it goes up, then peaks around middle age, and then falls down again in later years. Of course, these are just population averages and won’t tell you what will happen to any particular person. For some people, for instance, extraversion can increase with age instead of declining, and so on.
What may speed up the changes in personality are major life events: getting married, becoming a parent, and so on. If you are a married woman, and you’ve noticed that since the wedding your husband is happy to trade his party outfits for slippers, you are not alone. One study done on over three hundred spouses living in Florida revealed that over the first eighteen months of marriage, new husbands became much less extroverted. For those who find this disturbing, the upside is that said husbands also became more conscientious—that is, more likely to pick up their dirty socks from the bathroom floor. Women, on the other hand, became considerably less neurotic after the vows.
Other life events may also have an impact on personality. There are some reports that divorce increases extraversion in women, getting fired decreases conscientiousness, and joining the military can make you less agreeable. Practice makes perfect, as the saying goes, and since being newly single often forces women to go out more, doing so may increase their extraversion. Jobs tend to require conscientiousness, and losing them make us practise the trait less. Military training, meanwhile, encourages behaviours that don’t fit with agreeableness: aggression, for instance. The more we do something, the more we change.
But apart from waiting for love to strike or for Uncle Sam to call, you can take things into your own hands. You can change your personality traits at any age, even a very advanced one, although it is easiest done between the ages of twenty and forty. Some personality dimensions are harder to budge, such as openness to experience. Neuroticism, meanwhile, is the easiest trait to work on, which is good news from the longevity perspective. And here is some more good news: the process doesn’t need to take years. Interventions to alter people’s personality traits usually work after about eight to twenty-four weeks, depending on the study.
In one particularly thorough study, close to four hundred students from the University of Illinois at Urbana-Champaign and Michigan State University entered a fifteen-week program designed to help them change their personality traits. The whole idea was based on the principle of “fake it till you make it.” Each week, the students received a list of challenges to complete on the study website, ranging from very easy (“organize the app icons on your phone’s home screen”) to more difficult (“ask a co-worker, neighbour, or classmate to lunch or dinner”). They were to pick several tasks off the list—whatever took their fancy. The challenges were customized based on the student’s performance the week before: successful completion of several tasks meant the website would suggest slightly more difficult ones the next time. In case of a failure, easier options would pop up on the screen.
It all worked quite well. Students who wanted to increase their extraversion, for instance, and who completed a mere two challenges per week, increased this particular personality dimension by a fifth of a standard deviation over the semester. Using the height comparison, that would be like your average man growing over half an inch (1 cm). Not a tremendous shift, but certainly something. What still remains to be seen, though, is whether such change can be truly long-lasting or perhaps requires regular “reminder” interventions.
If you want to try some personality-shifting challenges at home, this study includes a handy list of tasks you can pick and choose. Just to give you an idea, here are a few examples.
To boost your extraversion:
Say hello to a cashier at a store.
Call a friend whom you haven’t spoken with in a while.
Go to a new restaurant or bar and chat with your server.
To work on your conscientiousness:
Set out your clothes the night before.
When you notice something you need to buy (e.g., household supplies), make a note on your phone.
Pay a bill as soon as you receive it.
To diminish neurot
icism:
When you feel overwhelmed, stop and take several deep breaths.
Before you go to bed, write down one good thing you can look forward to tomorrow.
When you feel worried about the future, spend at least two minutes visualizing the best-case scenario.
Seems tough? Well, you could always just pop a few magic mushrooms instead. Their active compound, psilocybin, has been shown to shift certain personality dimensions even after a single dose—although admittedly, that particular study was small and has yet to be replicated. One thing is certain, however: just thinking about changing your personality is not enough. You have to actually do something (and I’d strongly suggest going for the behavioural challenges, not the magic mushrooms). The payoffs can be substantial. Changes in personality traits over time are at least as important for longevity as are general levels of extraversion, neuroticism, or conscientiousness. Say there is one man, let’s call him Mr. Grumpy, who is quite neurotic, but stays more or less the same throughout his grumpy life. Now, a second man, Mr. Sulky, starts at a relatively lower level of neuroticism in his youth, but increases on the scale quite a lot as the years pass. Who will be worse off? A study of over a thousand American veterans suggested that Mr. Sulky may be in for trouble: increasing levels of neuroticism can push up the risk of dying by 40 percent—more so than the lifestyle of a couch potato.
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