From the global recession to student loan debts, being in the red isn’t good for your head.

They say money can’t buy happiness, but being in debt only makes things worse.

A recent review of 52 existing studies shows that debt and mental health are linked more closely than many believe.

Researchers at the University of Southampton in the U.K. found that fewer than nine percent of people without mental health problems—including depression, drug dependence, neurotic disorder, problem drinking, psychotic disorders, and suicide—were in debt.

More than a quarter of people with mental health problems were in debt.

“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,” study researcher Dr. Thomas Richardson, a clinical psychologist, said in a statement. “Equally, it might be that the relationship works both ways.”

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This doesn’t mean that debt causes mental health problems or vice versa because the study couldn’t show causality, and researchers say more studies are needed to better understand how the two are connected.

The new study was published in the journal Clinical Psychology Review.

A recent study published in the BMJ showed the stark realities of an economic recession: The global economic downturn lead to a 37 percent global unemployment rate and, in turn, a 3.3 percent rise in suicides. Those at the greatest risk were middle-aged men in the U.S. and young men in the U.K.

The U.S. and Canada saw 8.8 percent increases in suicide, while countries in the European Union saw a 13.3 percent increase.

“The rise in the number of suicides is only a small part of the emotional distress caused by the economic downturn,” the authors concluded. “Non-fatal suicide attempts could be 40 times more common than completed suicides, and for every suicide attempt, about 10 people experience suicidal thought.”

Another study, published in the journal PLOS One, showed the 2008 economic crisis increased feelings of depression and the use of antidepressant drugs, especially among those with the greatest stock holdings.

However, while people reported more feelings of depression, there was no evidence that the dramatic, sudden loss of wealth triggered clinically-validated indicators of depression.

A separate study showed that economic hardship may make the social exclusion of people with mental health problems worse. That study, also published in PLOS One, showed that this exclusion can be hardest on men and people with lower levels of education.

Mental health problems and social isolation increase a person’s likelihood of attempting, thinking about, or completing suicide.