Story highlights The most cynical people in this study had more than double the risk of dementia

Cynicism is also linked to higher rates of cancer-related deaths and cardiovascular disease

Cynical people tend to have a greater stress response, which can lead to inflammation

Your spouse "had to stay late at work" -- are you skeptical? Do you think your friend doesn't like you if he cancels dinner plans? Do you suspect that your co-worker is putting her ambitions ahead of the team?

Curmudgeons of the world, listen up: This line of negative thinking might actually hurt your health.

A new study in the latest edition of Neurology , the journal of the American Academy of Neurology, found that cynical people have a higher likelihood of developing dementia.

"There have been previous studies that showed that people who were cynical were more likely to die earlier and have other poor health outcomes, but no one that we could tell ever looked at dementia," said Anna-Maija Tolppanen , one of the study's authors and a professor at the University of Eastern Finland. "We have seen some studies that show people who are more open and optimistic have a lower risk for dementia so we thought this was a good question to ask."

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Studying cynicism

Cynicism is a deep mistrust of others. Psychologists consider it a kind of chronic anger that develops over time.

Specifically, the kind of cynicism researchers looked at involved doubting the truth of what people say and believing most people are motivated by self-interest rather than by what is best for the community.

The study tested 1,449 people with an average age of 71. The study participants took a test for dementia. A separate test measured their level of cynicism. Both tests are considered reliable by researchers.

The cynicism test asks if the person agrees with statements like "Most people will use somewhat unfair reasons to gain profit or an advantage rather than lose it"; "I think most people would lie to get ahead"; and "It is safer to trust nobody."

Those who agreed with the critical statements in the test were considered highly cynical. The people with the highest level of cynical distrust had a 2.54 times greater risk of dementia than those with the lowest cynicism rating.

Researchers also examined the test results to see if the subjects who were labeled highly cynical died sooner than the others. But once compounding factors were screened out, they did not. Previous studies have shown a link between cynicism and an earlier death.

Still, the new study does not prove that having a bad attitude causes bad health outcomes. To prove a causal relationship, a study would need randomized controlled trials to show that a reduction in cynical attitudes through treatment actually lowered the risk of bad health outcomes.

More research is necessary to replicate the conclusions. But the results complement a wide body of research showing how "over time, people with highly cynical hostility do worse health wise," said Dr. Hilary Tindle , assistant professor of medicine at the University of Pittsburgh.

Why cynicism may be bad for you

What might explain an association between cynicism and poor health?

This is a complex issue that needs to be studied more, Tindle said. The relationships between psychological attitudes and health outcomes are very complex.

"I can tell you from my clinical perspective from treating patients, I am absolutely certain that psychological attitudes can lead people down a road to poor health, because I see it every day when I talk to patients," said Tindle, who wrote the book "Up: How Positive Outlook Can Transform Our Health and Aging."

Tindle was the lead author on a study that examined the health outcomes of over 97,000 women and found that cynical women had a higher hazard of cancer-related mortality.

"The bottom line is that a high degree of anger/hostility/cynicism is not good for health," she wrote.

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Research shows cynical people also tend to smoke more, exercise less and weigh more. They also have a harder time following even the best medical advice, because their cynical natures won't let them believe what people tell them, Tindle said.

Past studies have also found that people who are cynical have a higher rate of coronary heart disease , cardiovascular problems and cancer-related deaths. Cardiovascular disease can contribute to dementia because it essentially damages small blood vessels everywhere in your body, including in your brain.

Cynical people also tend to have greater stress responses, which means they typically have a higher heart rate, a higher blood pressure peak, and a tendency to have greater inflammation of their immune systems. Chronic inflammation is now known to be harmful to one's overall health and it is linked to everything from Crohn's disease to high cholesterol to even Alzheimer's.

Can you come out of cynicism?

The good news is, being highly cynical is not a permanent state of mind.

"I am also certain that people can learn to change -- they change every day in that they quit smoking, they lose weight, they cut ties in unhealthy friendships," Tindle said. "The ultimate message is people are not 'doomed' if they have cynical tendencies."

So if your assumptions about people are making you angry and irritable, try having a little more trust.

"All of us are capable of adopting healthier attitudes," Tindle said. "As a physician, I see people of all ages making positive change every day."