College takes a heavy toll on a student’s mental health. The pressure of graduating on time, studying for exams and ultimately planning for a career can lead to increased anxiety, stress and even depression. But now, there’s a new item to add to the list: student loans.

A new study is one of the first to look at the link between student loans and mental health in young adults. Lead author Katrina Walsemann, an associate professor in the Department of Health Promotion, Education, and Behavior at the University of South Carolina, and her colleagues analyzed responses from 4,643 Americans born between 1980 and 1984. As the researchers suspected, the data show a clear trend: the higher the student’s loans, the poorer his or her mental health.

The respondents' psychological health was assessed via the Mental Health Inventory, a questionnaire that social scientists often use to measure a person’s psychological state. It asks how often a person felt nervous, calm and peaceful, downhearted and blue, happy, and down in the dumps over the past month. [9 Ways Going to College Affects Your Health]

The researchers also factored in a number of issues, such as the respondent’s current occupation, household income and highest level of education completed. They found that the only defining factor was the amount of loans in a person’s name; loans with higher amounts took a higher toll on that person’s mental health.

Surprisingly, student debt affected mental health regardless of a person's socio-economic situation, Walsemann told Live Science. So, for instance, if a surgeon and a kindergarten teacher borrowed equal amounts of student loans, they were likely equally as concerned about paying back those loans.

Walsemann and her colleagues found the average amount of student loans across their sample to be roughly $5,500 for students graduating as early as 2002 and as late as 2010. But, this number has dramatically worsened in recent years. In 2011, for example, 4 out of 10 graduating college seniors were leaving school with student loans averaging $23,300. And by 2013, 7 out of 10 graduating college seniors owed $28,000, on average, according to the Project on Student Debt.

There was one factor, however, that actually caused a reversal in the results. If a student was from a low-income family, his or her mental health actually improved with higher student loans. It’s likely that the loans helped the student earn a higher social standing, which helped increase that person's overall happiness, the researchers said.

“If student loans provide a vehicle for people who are coming from disadvantaged families to get a college degree, these student loans would help them become upwardly mobile and that might be important for their mental health,” Walsemann said.

But Walsemann also warned that the results could be skewed. Perhaps these students have a “personality characteristic that just makes them hardier and less prone to mental health problems in the face of a new disadvantage like debt,” she said.

Still, further research is needed to understand the impact of debt on young adults. After all, tuition prices are soaring. The price of higher education in the United States has increased by 250 percent, adjusting for inflation, over the last three decades alone, according to the new study.

“I think that what we found in our study is conservative because we are looking at a cohort who didn’t take out as much in student loans as young people today, who are in college [and who] are taking out [money] right now,” said Walsemann. 

In future studies, the researchers would like to look at additional factors, including whether young adults with higher debt choose specific occupations, stay in jobs longer due to security, get married earlier or wait longer to have children.

But despite its high cost, research shows that higher education is still a good investment. Studies have shown that a college degree may be a heavy price to pay for young adults, but in the long run it has a positive influence on income, job security, employment and even health.

The results of the new study were published in the January edition of the journal Social Science & Medicine.

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