Worrying and Intelligence: Scientists Find Evolutionary Link

April 18, 2012 — -- Do you worry too much?

Probably, because according to new research our capacity to worry evolved alongside our ability to think. So it's natural for us to worry, even about some things we can do nothing about.

The new work suggests that there is an evolutionary link between our tendency to worry and our intelligence, regarded as our most important evolutionary advancement.

"We think normally of worry as being disabling," said psychiatrist Jeremy Coplan, lead author of a study published in Frontiers in Evolutionary Neuroscience. That means it's a "maladaptive trait" that should have inhibited our adaptation to a changing environment, Coplan said in a telephone interview.

"So we found this strange juxtaposition of something that was supposedly disabling being linked positively with something (intelligence) that was very adaptive," he added.

The study, involving 26 patients with a disabling anxiety disorder and 18 healthy volunteers, was conducted by seven scientists at five institutions. Among the "normal" volunteers, those with the highest intelligence were the least likely to be excessive worriers. But the result was just the opposite among the patients. Those with higher intelligence and an anxiety disorder were likely to worry far more than those with a lower IQ score.

Thus there is a link between high intelligence and anxiety, the study says.

In addition, brain scans conducted by Sanjay Mathew at Baylor College of Medicine found that the cerebral white matter, where critical communications between brain cells are carried out, responded similarly to both worry and high intelligence.

Coplan, who is with the State University of New York's Downstate Medical Center, noted that worry is not in itself a bad thing. We do have real issues in our lives, and it's natural for us to worry about the possible outcome.

Even in the earliest days of human history, our ancestors worried about real threats, and they learned to avoid unsafe areas, thus surviving long enough to pass along their genes.

There's a flip side to that coin, of course. Scientists at Purdue University found that chronic worrying can kill you because it leads to unhealthy behavior, like smoking and consuming large quantities of alcohol. It can also lead to depression and neuroticism.

So when does worry become a bad thing? When does it become pathological?

"The cutoff, by definition, has to be arbitrary," Coplan said. There's no scale on which a score of 50 points means normal worry has become an anxiety disorder.

According to the diagnostic manual of mental disorders, he said, worry becomes pathological if it interferes in one of three areas of life -- recreational, occupational, and family functions.

But even that's not all that precise.

"Sometimes they may be able to hold down their job, and they may be able to fulfill their family obligations, but they just have no quality of life because they are worrying all the time," he said.

While the intensity may be hard to determine, there's no doubt that we all worry. After all, mental illness is primarily a matter of degree in that we all have traces of some pathologies, like anxiety, but when it becomes crippling it is time to seek professional help, Coplan said.

And anxiety is the most common human psychological experience, according to the journal Psychology Today.

Research published in that journal over the last few years has shown that we aren't particularly good at self-analyzing. Most of us think we worry more than the average person, for example.

But that's probably because we know we worry, but we don't know how much the other person worries. I know I worry a lot, but I'm not sure about you.