By now, the mind-body connection is a familiar idea. Most people are aware, for example, that stress can produce physical symptoms like an upset stomach, or that depression often physically hurts. But a growing body of research suggests that negative emotions and thoughts may also have links to other serious health problems, like heart disease.

“Many negative emotions such as anger, fear, and frustration become problematic when those emotions turn into a more permanent disposition or a habitual outlook on the world,” explains Emiliana Simon-Thomas, PhD, science director of the Greater Good Science Center at UC Berkeley.

Take cynicism, for example: A 2014 study published in the journal Neurology linked high levels of cynicism later in life, i.e. a general distrust of people (and their motives), to a greater risk of dementia compared to those who were more trusting, even after accounting for other risk factors like age, sex, certain heart health markers, smoking status, and more.

This way of thinking may also hurt your heart. A 2009 study from the journal Circulation looked at data from nearly 100,000 women and found that the most cynical participants were more likely to have heart disease than the least cynical folks. The more pessimistic women also had a higher chance of dying over the study period, versus those who were more optimistic about humanity.

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Another bad attitude that's been linked to poor health outcomes: hostility. According to a 2014 study published in the journal Stroke, people who scored higher on measures of unfriendliness, as well as those with chronic stress and depressive symptoms, had a higher risk of stroke than the friendlier, kinder participants.

Finally, there's depression, which is a serious diagnosis that can have repercussions far beyond feeling sad or losing your appetite. It's been connected with an increased risk for type 2 diabetes, heart attack, and a greater chance of disability later in life. (This is another reason why it's so important to seek help for depression.)

Our thoughts and emotions have widespread effects on bodily processes like metabolism, hormone release, and immune function, Simon-Thomas says. One theory is that when you're stressed or depressed, cortisol levels increase, making your immune system less able to control inflammation, which could lead to disease over time.

It could also be that people who feel bad—be it depressed, stressed, cynical, or otherwise—may also be more likely to smoke or drink alcohol, or less likely to be physically active, all things that can affect your health, of course. Or it's possible that negative emotions might be an early symptom of a health problem, rather than a cause.

All this said, there is a big bright spot for every Negative Nancy out there: by simply changing your perspective, you may just improve your health. “We know that neural pathways are changing every minute of your entire life and that your brain is generating new cells throughout your life. And this neurogenesis is not only associated with the formation of new memories, but with mood stability, as well,” Simon-Thomas says.

So cynics take heart—you have control over your attitude (and your well-being). As Simon-Thomas put it: “We can be deliberate about shifting our habits of feeling and thinking in the world.”