In a study of the love lives of 859 American adolescent couples (Personality and Social Psychology Bulletin), the combination of a stereotypically butch, masculine boy with an ultra-feminine, girly girl was more likely to have sex and to do so at an earlier age, than less stereotypical combinations. Couples in which both parties were averagely masculine and feminine were three times less likely to have sex than the butch/fem duos, the slowest to get around to having sex and the quickest to break up. Of course, the strongest predictor of all was whether they had already lost their virginity - couples where both had done so were 10 times more likely to have sex than ones where both were virgins. Implication: get out the fire extinguisher if your Britney Spears lookalike 14-year-old is dating her male equivalent - or then again, maybe not, depending on your point of view and whether the girl is on the pill.

The massive rise in the number of cases of Alzheimer's disease is usually explained by our increased longevity. However, a review of studies of the effect of benzodiazepines, such as Valium, raises an alarming possibility (Psychological Medicine). While two studies found that ever having used them reduced the likelihood of developing the illness, and another two found no effect, three did find increased numbers of users or ex-users among Alzheimer's patients. The authors stress the need for further studies, but conclude that there may be a significant likelihood that using these pills increases your risk.