The 'anti-drug' is what the US National Youth Anti-Drug Media Campaign calls parents, and many more programs designed to curb or prevent substance use among teenagers give at least give lip service to the importance of parents in any such effort.

In pursuit of hard evidence that parents are the key to keeping kids straight and sober, Jane Petrie of the Dacorum Primary Health Care Trust in Hertfordshire UK, and colleagues at the Centre for Research in Primary and Community Care at the University of Hertfordshire combed through 1,617 studies.

The team identified 20 evaluations of programs to prevent tobacco, alcohol, or drug use in children under the age of 18 that had a parenting component and purported to use sound research methods (ie. either a randomized control trial or another measure that over time compared children who participated in a program to sufficiently similar children who did not participate). Although most of the studies took place in the US there were also examples from Russia, Australia, and Norway.

The general quality of the studies was only fair according to Petrie and her colleagues. So they are hesitant to make any firm declaration about the power of parents to end substance abuse. However, they did find some common themes among the apparently more successful programs.

Actively involving parents with their children appeared to be effective. Some programs put children and their parents to work in group exercises, while others encouraged parents to engage kids in family activities. Some taught parents how to manage conflict and maintain strong family bonds. By contrast, the least successful programs did not involve parents actively. Often they just sent them information in the mail.

The more effective programs also tended to focus quite generally on children’s social competence and ability to regulate themselves rather than pinpointing substance use behavior.

As always seems to be the case, more and better research is needed. But for those who can’t wait for future studies to be completed, the existing evidence provides some clear signposts. Parents can be an 'anti-drug' if they are successfully recruited to be actively involved in the lives of their children.

• Summary of "Parenting programmes for preventing tobacco, alcohol or drugs misuse in children: a systematic review" by Jane Petrie, Frances Bunn, and Geraldine Byrne in Health Education Research, 2007 Volume 22, Number 2, pp177-191.