Depression is on the rise among millennials.
© JGI/Tom Grill/Getty ImagesDepression is on the rise among millennials.
Major depression is on the rise among millennials - but one in five of them don't seek treatment, according to research released by the Blue Cross.

According to a recent report analyzing data from the Blue Cross Blue Shield Health Index, major depression diagnoses are rising at a faster rate for millennials and teens compared to any other age group.

Since 2013, millennials have seen a 47% increase in major depression diagnoses. The overall rate increased from 3% to 4.4% among 18 to 34 year olds.

These findings were underscored by an additional Blue Cross Blue Shield report on millennial health. It analyzed the data of 55 million commerically insured American millennials, there defined as aged 21 to 36 in 2017. It found that major depression had the highest prevalence rate, or the likelihood of a person having a disease, among health conditions affecting millennials.

The most prominent symptom of major depression is "a severe and persistent low mood, profound sadness, or a sense of despair," according to Harvard Medical School.

Blue Cross also found that millennials are less healthy than Gen Xers were at their age, and that they're likely to be less healthy than Gen Xers when they're older.

In total, two million commercially insured Americans diagnosed with major depression aren't seeking treatment.

Pricey healthcare and burnout are making millennials unhealthy

Millennials' adverse health and their reluctance to get help may be related to rising healthcare costs and increasing levels of burnout.

Healthcare is one of four key costs plaguing millennials. In 1960, the average annual health-insurance cost per person was $146 - in 2016, it hit $10,345. When adjusted for inflation, that's a nine-fold increase. Costs are expected to increase to $14,944 in 2023.

In fact, more millennials than baby boomers have declined medical or dental treatment because it was too costly, according to an INSIDER and Morning Consult survey.

Meanwhile, cases of burnout have been increasing at an alarming rate over recent years, reported Business Insider's Ivan De Luce. The World Health Organization recently classified burnout as a "syndrome," medically legitimizing the condition for the first time.

It's a growing problem in today's workplace because of trends like rising workloads, limited staff and resources, and long hours - particularly for millennials, who consider themselves the " burnout generation."