Specialist services are needed for teenagers, say charities
Teenagers who have minor depression are at a higher risk of mental health problems later in life, a study says.
Psychiatrists at Columbia University and the New York State Psychiatric Institute spoke to 750 people.
Anxiety, severe depression and eating disorders were all far more common in 20 and 30-year-olds who had had minor depression as adolescents, they found.
The British Journal of Psychiatry report said further research was needed to unpick the reasons for the link.
UK charities said specialist services for young people were vital.
The study was based on interviews with 750 14 to 16-year-olds who were then assessed again as adults.
It found that 8% of participants had minor depression as teenagers.
By the time they got to their 20s and 30s, the risk of them having major depression was four times higher than those who did not have signs of minor depression at the first interview.
There was a two-and-a-half times increased risk of agoraphobia, anxiety and obsessive compulsive disorder and a threefold risk of anorexia or bulimia.
The researchers defined minor depression as milder than clinical depression but lasting at least two weeks and including symptoms such as feeling down, losing interest in activities, sleeping problems and poor concentration.
Study leader Dr Jeffrey Johnson said more research was needed to see if depression problems in teenagers were an early phase of major depressive disorder or if minor depression earlier in life contributed to the development of more serious problems later on.
Lucie Russell, director of campaigns at Young Minds, said the study highlighted the importance of giving teenagers the right support when problems first arise.
"Ensuring teachers, social workers and the rest of the children's workforce have the appropriate skills and knowledge to identify when a child is showing signs of depression will enable young people to get help early before problems escalate to crisis point."
But she added that access to specialist services was a problem with some parts of the country having year-long waiting lists.