Teens suffering from depression and bipolar disorder need to be monitored for early heart disease because their mental illness puts them at risk for many of the conditions that lead to a damaged heart.

In a new scientific statement, the American Heart Association asks that doctors watch for heart and blood vessel disease among severely depressed teens.

Dr. Benjamin Goldstein, a child-adolescent psychiatrist at Sunnybrook Health Sciences Centre and the University of Toronto was the lead author of the statement. He says that until recently, teens with mental illness were not widely recognized as being at increased risk for early heart disease.

But he and his fellow researchers say that recent studies have found that mood disorders should be considered "moderate" risk factors for heart disease.

After analyzing the published research on the topic, the authors found that teens with depression or bipolar disorder are more likely than other teens their age to have:

• high blood pressure

• high cholesterol

• obesity, especially around the midsection

• type 2 diabetes

• and hardening of the arteries.

They also point to a 2011 study of more than 7,000 U.S. young adults, which found that a medical history that includes depression or an attempted suicide was the number one risk factor for heart disease death from clogged arteries in young women. In men, it was the fourth biggest risk factor.

While teens with mood disorders were more likely than other teens to engage in unhealthy behaviours such as smoking and being physically inactive, the doctors say those factors alone do not explain their raised heart disease risk.

Dr. Goldstein says doctors should be ready to take action to help these patients at the earliest possible stage."

"Mood disorders are often lifelong conditions, and managing cardiovascular risk early and assertively is tremendously important if we are to be successful in ensuring that the next generation of youth has better cardiovascular outcomes," he said in a statement.

Researchers already know that adults with depression and bipolar disorder experience heart disease at much earlier ages than other adults. The reasons aren't fully clear but sleep deprivation, inflammation and other types of cell damage from stress could play a part.

Since cardiovascular disease can begin early in life, the heart experts wanted to increase awareness that mood disorders in youth raise the risk for heart disease.