Hyperactivity in young girls may be linked to adjustment problems such as poor performance in school, abusive relationships and teen pregnancy, a new Canadian and British study suggests.

"Girls with high levels of hyperactive and physically aggressive behaviours, and girls with hyperactive behaviours only, are at risk of facing problems in adulthood," said lead author Nathalie Fontaine, with the Department of Psychology at University College London.

These problems include poor performance in school, abusive relationships, nicotine addiction and a reliance on welfare assistance.

Fontaine, noting that the results were similar to studies conducted on hyperactive boys, said prior to this study, the research had focused on boys.

"Most of the previous research on hyperactivity and aggressive behaviours concerned boys," she told CBC News via e-mail. "Little is known about this topic in girls, notably the consequences of these behaviours and how to prevent them."

Researchers from the University College London and the University of Montreal studied 881 girls in Quebec from age six through 21, asking teachers and parents to report behaviour problems such as restlessness and being fidgety and physical aggression.

One in 10 girls demonstrated high levels of hyperactive behaviour, while another one in 10 showed signs of both hyperactivity and physical aggression.

By the time the girls were 21, those who were most hyperactive or aggressive were more than twice as likely to become smokers and four times more likely to perform poorly at school.

"Elementary schoolgirls with the highest levels of hyperactivity were at high risk of serious adjustment problems in adulthood," the authors wrote.

Girls with both hyperactivity and physical aggression, about 8.5 per cent of the sample, reported problems of abusive relationships, early pregnancy and dependency on welfare.

However, Fontaine noted, "Not all hyperactive girls are at risk of future difficulties. About 25 per cent of the girls with high levels of hyperactive behaviours in childhood did not show adjustment problems [in] early adulthood."

Fontaine said the findings can used to help schools, clinicians and researchers design and implement "preventive interventions" for girls as early as possible.

"Our study suggests that girls with hyperactive behaviours in childhood should be a primary target for intensive prevention programs because they are at risk for serious problems later in life," Fontaine said.

She said future research should focus on factors that trigger hyperactive behaviours, look at what is happening before kindergarten, and the development, implementation and assessment of preventive interventions for girls.

The study is published in the March issue of Archives of General Psychiatry.