Some experts call it “the new great depression.” Since the rise of social media, depression and feelings of hopelessness have skyrocketed among teens. According to a new poll, nearly half of teens now say they agree with phrases like “I can’t do anything right,” “I do not enjoy life” and “My life is not useful”—roughly twice as many as did just a decade ago.

Psychologist Dr. Jean Twenge says, “These are staggering numbers, just enormous increases, and parents are rightfully very concerned about their children’s mental health.”

The poll, conducted by the University of Michigan is just the latest startling revelation about youth mental health, as rates of teen anxiety and depression have grown.

The number one cause, according to Twenge, is social media and screen time. In fact, rates of teen depressive symptoms have increased massively since the mass popularization of the smartphone in the early 2010. “There’s no question that is the primary cause of the increase in teen depression now,” Twenge said. “It’s by far the largest change in teens’ everyday lives over the past 10 to 12 years. Nothing else even comes close.”