Hallucinogen, opiate, sedative and stimulant use and abuse in a population-based sample of female twins.

OBJECTIVE: Rates of illicit psychoactive substance use and abuse in women have increased substantially over the last 50 years. However, we understand little about the aetiology of these behaviors in women, and almost nothing about the role of familial-environmental and genetic factors.
METHODS: We obtained, by means of blind telephone interviews with 1934 individual twins from female-female adult pairs ascertained through a population-based registry, including both members of 500 MZ and 326 DZ pairs, a history of lifetime illicit use, abuse and dependence, as defined by DSM-IV, of hallucinogens, opiates, sedatives and non-cocaine stimulants.
RESULTS: Lifetime prevalences for substance use ranged from 3.3% for opiates to 10.4% for hallucinogens. Rates of abuse (ranging from 0.7% for opiates to 3.2% for stimulants) and dependence (ranging from 0.2% for hallucinogens to 1.4% for stimulants) were substantially lower. Significant twin resemblance was found for hallucinogen use, opiate use, sedative use and stimulant use, abuse and symptoms of dependence. The results of twin-model fitting suggested that twin resemblance for hallucinogen and stimulant use was due to both genetic and familial environmental factors, while twin resemblance for opiate and sedative use as well as stimulant abuse and symptoms of dependence was solely the result of genetic factors. Heritability of liability ranged from 21% to 72%. Twin resemblance for substance use, abuse and dependence could not be explained by the similarity of the twins' environment in childhood, adolescence or adulthood.
CONCLUSION: Although limited by the rarity in women of these forms of substance use and misuse, our results none the less suggest that familial factors, which are at least in part genetic, strongly influence the vulnerability to hallucinogen, opiate, sedative and stimulant use and abuse in women.