Well here's a good reason to pay off your credit card debt: A new review of studies shows that people in debt have a higher risk of mental health problems.

Researchers from the University of Southampton found that psychological conditions like depression and neurosis were far more prevalent among people with debt, compared with people not in debt.

"This research shows a strong relationship between debt and mental health; however it is hard to say which causes which at this stage," study researcher Dr. Thomas Richardson, a clinical psychologist at the university, said in a statement. "It might be that debt leads to worse mental health due to the stress it causes. It may also be that those with mental health problems are more prone to debt because of other factors, such as erratic employment. Equally it might be that the relationship works both ways."

For instance, Richardson noted, a mental condition such as depression could both spur debt, and also make debt worse. "People who are depressed may struggle to cope financially and get into debt, which then sends them deeper into depression."

The review of 65 studies, published in the journal Clinical Psychology Review, showed that the likelihood of having a mental health problem is three times higher among people who also have debt, compared with people without debt.

Researchers found that fewer than 9 percent of people without mental health problems were in debt. Meanwhile, more than 25 percent of people with a mental health problem were in debt.

Mental health problems that were particularly linked with debt included suicide, depression, psychotic disorders, drug dependence, problem drinking and neurotic disorder. However, researchers did not find an association between smoking and debt.

Previous studies have also linked debt with poorer health. A 2000 study from Ohio State University researchers showed that the stress that comes from having high credit card debt was linked with worse reported health. And a study published earlier this year in the journal Social Science and Medicine showed that financial debt is linked with poorer self-reported health and higher blood pressure among young adults.