Young adults having multiple sex partners are at greater odds of developing alcohol or drug dependency and they breed social disorders, reveals a New Zealand research. The findings from Otago University which emerge from the long-running Dunedin Multidisciplinary Health & Development study show that the odds of substance disorders were much higher for young women. Substance disorder involves not only significant use of the substance but also impairment in social, occupational or recreational activities, the journal Archives of Sexual Behaviour reports. Using data from the world-renowned study, tracking the health and behaviour of more than 1,000 people since their birth, in Dunedin in 1972-73, researchers examined how many sex partners the study members reported during three age periods (18-20 years, 21-25 years & 26-31 years). They then looked at data on their mental health immediately after each period (at ages 21 years, 26 years, and 32 years), including anxiety depression and substance dependence, according to an Otago statement. Sandhya Ramrakha from Otago, who led the study says: \"This ruled out the possibility that men and women already had substance problems and that this had led to them having more sexual partners.\" Women who had 2.5 or more partners per year were found to have boosted odds of substance dependence disorder in each age period. The odds increased between seven and 17 fold. \"Furthermore, when we used a model to compare men and women who had more than 10-20 sex partners in the same periods, we found that these women were much more likely to have a substance disorder than the men,\" Ramrakha says. Researchers suggest several possible explanations for the intertwining of these behaviours that happen in adolescence and young adulthood. One of them is alcohol. \"The role of the alcohol industry in encouraging the view that alcohol is entertainment, targeting young women in particular, is disturbing. Young women are also encouraged to \'keep up\' with young men in relation to their drinking,\" says Ramrakha.