An analysis of data from the National Health and Nutrition Examination Survey (NHANES) has found that people who were regularly online had a significantly higher risk of being diagnosed with major depressive disorder (MDD) than those who did not use the internet at all.

“The results support a causal link between internet use and the risk of MDD,” said study co-author Dr. Matthew Miller, an epidemiologist at the University of Colorado, Denver.

Miller and his colleagues looked at data from NHANES from 2005 to 2010 and examined the association between internet usage and depression in people with at least one diagnosis of depression.

In the analysis, they examined data from 3,600 adults who were part of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a nationally representative sample of Americans aged 18 and older.

They also analyzed data from a national sample of adults who answered questionnaires about their Internet use and depression, using data from two sources: the National Survey on Drug Use and Health and a survey of more than 12,000 adults conducted by the University at Buffalo.

The study found that those who used the internet to browse the internet more frequently had a 28 percent higher risk than those with a lower frequency of internet use.

For people with two or more diagnoses of depression, the risk increased to 47 percent higher.

Those with depression who were more than 50 years old were three times as likely to have been diagnosed with depression than those without any other diagnosis.

Miller said the results suggest that frequent internet use may increase the risk for depression in some people.

He added that while the study does not prove that internet use leads to depression, it does provide a strong case that people should try to reduce their Internet usage.

“We should be very cautious when we look at any new evidence, especially when it comes to mental health, that says there is no benefit,” Miller said.

Miller also said that there are some limitations of the study.

For one, the sample size was small, and it is unclear whether the results reflect people with depression or other mental illnesses.

Also, it is possible that the Internet is used more often in the United States than elsewhere, Miller said, which could mean that the risk is higher for people who use it regularly.

“That said, it appears that there is a risk for those who use the Internet regularly, particularly in older adults, and that it is a cause for concern,” Miller added.