[Bayonet finger and the use of illicit drugs].

Prevalence of "bayonet finger", a semiologic sign of attention deficit and hyperactivity disorder (ADHD), was determined in male illicit drug users, admitted in psychiatric hospital. A control group, paired in sex, age and social status, was built from the general population. The sign was observed en 165/345 (47.8%) drug users and 13/50 (26%) controls, the difference being statistically significant. Bearers of this sign had 2.61 odds ratio, 1.84 relative risk and 92.7% probability for being drug users. The observations suggest that, for males: (1) ADHD and related syndromes should be present in approximately half of illicit drug users and should represent a vulnerability factor for becoming drug user; (2) individuals presenting "bayonet finger", mainly adolescent, should deserve special attention for prevention of drug use.