Hello, and I hope I can help you today. Mentally challenged adults may have intellectual difficulties, but their sexual development is generally normal for age and most special needs adults will have issues and curiosities related to their sexuality. In certain situations, mentally challenged adults experiment with sex and are capable of consensual sexual relations. The frontal lobe of the brain, which normally controls impulses, is not as well developed in adults who are mentally challenged, so inappropriate remarks and behaviors in public are not unusual. Unfortunately, there are no medical treatments that consistently suppress libido. In males, testosterone is the main cause of libido, and anti-testosterone medications have been used in sex offenders and other males for suppression of their sex drive. However, the female sex drive is extremely complicated, and not necessarily hormonally mediated, which makes treatment more difficult. The most successful hormonal suppressive treatment that I ve seen in mentally challenged females is the injectable contraceptive Depo-Provera. It will prevent pregnancy as well as decreasing the hormonal fluctuations associated with menstruation. Depo-Provera is also used in sex offender therapy, so it must have some effect on libido, so I would suggest this is a first recommendation to discuss with her doctors to see him might be beneficial in her case. It is helpful that your daughter is in therapy, and I encourage you to discuss the situation with her therapist as well. I hope that I was able to adequately answer your question today, and that my advice was helpful. Best wishes, Dr. Brown