Washington: Teens and adults interpret abstinence differently, which explains why such programmes are unable to prevent teenage sexual activity, according to a new study.

"Interventions that have been created to encourage abstinence have treated abstinence and sexual activity as opposites. However, teenagers say they don't think of them as opposites," said Tatiana Masters, co-author of the study and Washington University doctoral student.

"These interventions are less likely to work than more comprehensive sex-education programmes because they are not meeting adolescents where they are, and they are speaking a different language."

The study showed that attitudes and intentions about sex were more powerful than attitudes and intentions about being abstinent.

"This paper demonstrates that increasing abstinence intention does not lead to less sex. In fact, when abstinence intention and sex intention interact with each other a teenager is more likely to have sex," said Masters.

Rather than being an either or choice, she said, a teenager's decision to become sexually active can be likened to getting on an escalator. At first, adolescents don't think about sex very much. Once they step on the escalator the first step is abstinence. Then as they begin to be aware of sex, there are other steps and choices to be made that eventually lead to having intercourse.

The study involved 365 adolescents - 230 girls and 135 boys - recruited from community centres, youth programmes and after-school programmes for a larger research project testing an intervention to reduce HIV risk behaviour among young teenagers in Seattle.

The participants filled out questionnaires before starting the larger HIV intervention, eight weeks later when the intervention was completed, and then six and 12 months later. The questionnaires assessed the adolescents' attitudes and intentions about being abstinent and having sex and also asked about their sexual activity in the previous six months.

At the start of the study, 11 percent of the boys and four percent of the girls had had sexual intercourse. Those numbers increased to 12 percent of the boys and eight percent of the girls six months later and 22 percent of the boys and 12 percent of the girls one year later.

Currently there is no federal funding for any comprehensive sex-education programme in the country, but funding for abstinence-only programmes has mushroomed, increasing from $9 million in 1997 to $176 million in 2007.

Masters added: "The US has the highest teen pregnancy rate. And rates of sexually transmitted diseases in this country are high. The risks are real, and if people want to keep teens safe from the negative outcomes of sex, abstinence-only programmes are not the way to go. IANS