Left-handedness is statistically linked to lifetime experimentation with illicit drugs

Abstract

Handedness has been linked to an enhanced risk of alcohol abuse, while less is known about other drugs. A convenience sample of 1004 male and female Italian participants (females=58%) from the general community (18 to 65 years old: average age = 30; standard deviation = 10, median = 25) was asked about: handedness (preference in writing); lifetime use of alcohol, tobacco, and illicit drugs; levels of psychological distress, as measured by the General Health Questionnaire (GHQ); and levels of delusion proneness, as measured by the Peters et al. Delusions Inventory (PDI). Overall, 92 individuals (9.2%) were classified as left-handed, with no significant difference reported among genders. Lifetime use of illicit drugs, primarily cannabis, was reported by 20% of the sample. In a multiple logistic regression analysis, after taking into account sex, age, and caseness on GHQ and PDI, left-handed people in the sample were statistically more likely to report lifetime experimentation with heroin, ecstasy/amphetamine, and, marginally, hallucinogens, but not alcohol or tobacco. Different mechanisms might contribute to an explanation of greater lifetime experimentation with some illicit drugs among left-handed people as compared to right-handed people. However, replications with clinical samples are necessary before any definitive statements can be made.