Acute yohimbine increases laboratory-measured impulsivity in normal subjects

Background: State-dependent changes in impulsivity many be related to norepinephrine. To examine possible relationships between nompinephrine and acute changes in impulsivity we measured effects of yohimbine, which increases norepinephrine release by blocking alpha-2 noradrenegic receptors, on laboratory-measured impulsivity in healthy subjects without psychiatric or substance-use disorders. Methods. Impulsivity was assessed using The Immediate and Delayed Memory Tasks (IMT-DMT), derived from the Continuous Performance Test, before and after placebo or-two doses of yohimhine, given 4 days apart. Blood pressure was monitored, and psychiatric symptoms were measured using self-rated visual analog scales. Results: Yohimbine was associated with a dose-relaled increase in impulsive IMT commission errors, with an increase of > 50% relative to baseline at the higher close. The activation factor of the Internal State Scale was increased at the same close. Conclusions: These results are consistent with increased impulsivity in normal subjects given yohimhine, possibly related to increased norepinephrine.