Women who start their period earlier than their peers are more likely to experience depression well into their late 20s, new research claims.
Researchers said this may be due to a mismatch between how girls look and cognitive and emotional maturity.
The average age girls start menstruating is 12, but researchers say one-third American girls are now entering puberty by the age of eight.
Previous studies have linked early maturing in young girls to psychological vulnerability in their teen years, but this is the new study led by Cornell University reveals that the impacts may last far longer than previously thought.
Researchers found women who start menstruating at a younger age are psychologically vulnerable well into adulthood
Dr Jane Mendle, associate professor at Cornell University, said the findings reveal that puberty has long-term effects.
'Early maturers may look old, but they still think and feel like other girls their age,' Dr Mendle told Daily Mail Online.
'This mismatch can sometimes make it more difficult to adapt to all of the new changes and experiences that accompany this transition,' she added.
Depression is common mental health disorder that is most common in women in their late 20s and early 30s, according to the Anxiety and Depression Association of America.
For the study, Dr Mendle and her colleagues tracked 7,800 girls for 14 years, from adolescence to their late 20s, using data from the National Longitudinal Study of Adolescent Health.
The subjects were between 11 and 21 years old when researchers started tracking them and were asked about when they began menstruating and about any symptoms of depression and antisocial behavior they had experienced throughout their lives.
The researchers also asked the girls and women about other