A study of 881 Canadian girls which followed them from the ages of six to twenty-one looked into how hyperactive or aggressive behaviour in childhood could affect early adulthood. The researchers found that one in ten of the girls monitored showed high levels of hyperactive behaviour and another one in ten showed high levels of hyperactivity and physically aggressive behaviour. Hyperactive and/or aggressive girls were more likely to take up smoking and perform poorly in school. Girls with both hyperactivity and physical aggression reported more physical and psychological aggression towards their partners, were more likely to become pregnant and were more likely to be dependent on welfare.
You can find out more about this research at