The brains of people who experience depression or anxiety may age more quickly than other people.

And researchers in a new study say this increases their odds of developing dementia.

According to the National Institute of Mental Health about 16 million adults in the United States (almost 7 percent of all American adults) had experienced at least one major depressive episode in the past year.

In addition, depression is the leading cause of disability in the United States for people ages 15 to 44.

The 2005 Harvard National Comorbidity Survey estimates that 19 percent of U.S. adults had an anxiety disorder during any given year and almost 31 percent of U.S. adults experience an anxiety disorder at some point in their lives.

“The main difference between normal anxiety and an anxiety disorder is how much it disrupts your ability to function and how long it lasts. Anxiety related to something that produces anxiety is normal, but if it persists for weeks, that may be anxiety disorder,” Dr. Gail Saltz, clinical associate professor of psychiatry at the New York Presbyterian Hospital Weill-Cornell Medical College and author of “The Power of Different: The Link Between Disorder and Genius,” told Healthline.