Failure to look before leaping: The Barratt Impulsiveness Scale predicts treatment completion in cocaine- and methamphetamine-dependent patients.

Greater impulsivity as assessed by the Barratt Impulsiveness Scale-11 (BIS-11) and the Stroop has been associated with treatment outcomes in patients with stimulant use disorders. The present study evaluated the relationships among impulsivity, baseline stimulant use status, and treatment outcomes in methamphetamine- and/or cocaine-dependent participants. Six sites participating in protocol CTN-0031 (Stimulant Abuser Groups to Engage in 12-Step (STAGE-12)), a multi-site clinical trial evaluating 12-step facilitation for stimulant abusers, obtained the Stroop and BIS-11 from 183 methamphetamine- and/or cocaine-dependent participants. The relationships of the BIS-11 and Stroop to baseline stimulant use and treatment outcomes through 6-month follow-up were evaluated. Methamphetamine-dependent, relative to cocaine-dependent, participants evidenced greater impulsivity as measured by BIS-11 total score. There was a trend for poorer response inhibition, as measured by the Stroop, in cocaine-dependent, relative to methamphetamine-dependent participants. When accounting for other factors related to treatment completion, the BIS-11 Motor Impulsiveness Score, which assess the tendency to act without thinking, was predictive of treatment completion status. No relationship greater than r=0.2 was observed between impulsivity and stimulant use during either baseline or treatment/follow-up.

Conclusions: BIS-11 Motor Impulsiveness was a significant predictor of treatment retention. Treatment-seeking methamphetamine and cocaine-dependent patients may have different impulsivity profiles.