Now in year 7 at Homebush Public School, Annaliese appears in front of crowds as she competes in state public speaking competitions, has a close circle of friends and describes herself as ''independent''.

She says her confidence came about because of early intervention received from the age of four after her mother, Kathy Wicks, signed her up to a Macquarie University anxiety study. Along with 200 other children, Annaliese and her mother have been interviewed at the university's centre for emotional health every few years since then, as researchers track the impact of anxiety over the course of a child's life.

''What we have found is that maternal anxiety, parental over-involvement, negativity and attachment issues at age four are all associated with increased anxiety at age six, and anxiety was likely to be ongoing as they grow up,'' said a professor with the university's department of psychology, Jennifer Hudson.

''Anxiety is sometimes referred to as a gateway illness, because those who have it are more likely to develop depression and substance abuse problems later in life.''

Her findings, published in the Journal of the American Academy of Child & Adolescent Psychiatry, found toddlers with behavioural inhibitions were significantly more likely to be diagnosed with social phobia and generalised anxiety disorder at follow-up.

Up to 10 per cent of preschoolers have clinical anxiety, Professor Hudson said, and intervention before school age was cost-effective because those who struggled early often had a hard time in university and the workplace.

She is now looking for parents of confident preschoolers to take part in a study of how their children differ from those who are more shy and inhibited. The centre is also looking at the role of fathers, ''because dads usually like rough-and-tumble play and encourage risk-taking, which is beneficial to children''.