Young adults who spend hours a day on social media are at heightened risk of developing depression in the near future, new research from the United States suggests.

In recent years, a number of studies have linked heavy social media use to an increased risk of depression.

“But then you have to ask the chicken-and-egg question,” said study author Dr. Brian Primack, a professor of public health at the University of Arkansas, in Fayetteville, USA.

On one hand, he said, excessive time on Twitter or Facebook might fuel depression symptoms. On the other, people with depression might withdraw from face-to-face interactions and spend more time online.

So Primack and his colleagues decided to see whether social media use made a difference in young adults’ risk of future depression.

It did, according to their report, which was published online this month in the American Journal of Preventive Medicine.

The study included nearly 1,000 adults aged 18 to 30 who were depression-free at the outset, based on a standard questionnaire. All reported on their usual social media time and were assessed for depression again six months later.

By that time, nearly 10 percent fit the criteria for depression.

Overall, depression risk rose in tandem with time spent on social media. Compared with the lightest users – 2 hours or less per day – the heaviest users – at least 5 hours per day – had a three times higher depression risk.

Meanwhile, that risk was two times higher among young adults who were active on social media around 3.5 to 5 hours per day.

Primack noted that the findings do not definitively prove cause and effect.

However, he added, his team accounted for factors like people’s education level, income, race and whether they were employed.

They also asked participants whether they’d experienced childhood traumas like physical abuse and emotional neglect, which are also risk factors for depression.

Even then, excessive time on social media predicted a higher depression risk.

And, Primack said, there was no evidence the relationship went the other way: Among 299 other study participants who were depressed at the start, there was no increase in social media use over time.

Nathaniel Counts is senior vice president of behavioral health innovation for the nonprofit Mental Health America.

He said the researchers did a good job of accounting for other factors that could explain the link between social media use and depression.

However, depression is complicated, and it’s difficult to tease out the role of a single factor, Counts added.

For example, he said that a young person could be dealing with a difficult family situation, then start to spend more time on social media as an escape.

That online time might precede depression, but not be a cause of it. CURRENTPH