The effects of oral d-amphetamine on impulsivity in smoked and intranasal cocaine users

Abstract

BACKGROUND Effective treatments for cocaine use disorders remain elusive. Two factors that may be related to treatment failures are route of cocaine used and impulsivity. Smoked cocaine users are more likely to have poorer treatment outcomes compared to intranasal cocaine users. Further, cocaine users are impulsive and impulsivity is associated with poor treatment outcomes. While stimulants are used to treat Attention Deficit Hyperactivity Disorder (ADHD) and attenuate certain cocaine-related behaviors, few studies have comprehensively examined whether stimulants can reduce behavioral impulsivity in cocaine users, and none examined route of cocaine use as a factor. METHODS The effects of immediate release oral d-amphetamine (AMPH) were examined in 34 cocaine users (13 intranasal, 21 smoked). Participants had three separate sessions where they were administered AMPH (0, 10, or 20 mg) and completed behavioral measures of impulsivity and risk-taking and subjective measures of abuse liability. RESULTS Smoked cocaine users were more impulsive on the Delayed Memory Task, the GoStop task and the Delay Discounting Task than intranasal cocaine users. Smoked cocaine users also reported more cocaine craving and negative mood than intranasal cocaine users. AMPH produced minimal increases on measures of abuse liability (e.g., Drug Liking). CONCLUSIONS Smoked cocaine users were more impulsive than intranasal cocaine users on measures of impulsivity that had a delay component. Additionally, although AMPH failed to attenuate impulsive responding, there was minimal evidence of abuse liability in cocaine users. These preliminary findings need to be confirmed in larger samples that control for route and duration of cocaine use.

Acute effects of amphetamine and related psychostimulants on impulsivity: a systematic review of clinical trials

“…Several studies did include at least three tasks designed to measure different aspects of impulsivity 46,48,49,54 ; however, the tasks used in these studies differed substantially, precluding meaningful comparisons between them. This review illuminates the need for future studies to incorporate multiple tasks designed to measure different aspects of impulsivity, if more practical comparisons are to be elucidated.…”

“…49,53,60 The remaining studies did not report the duration of washout periods [44][45][46][50][51][52]56 or used parallel-group designs. 48,59 The most widely used behavioural impulsivity tasks were the Stop-Signal Task, [49][50][51][52]55,60 Stop/Go Task/Stop Task, 28,46,47,54,57 Go/No-Go Task, 43,53,54 Delay Discounting Task (DDT) 45,46,54 and Balloon Analog Risk Task (BART). 45,49,58 Less commonly used tasks Probability Discounting Task (DPDT), 54 Immediate Memory/Delayed Memory Task, 46 Modified Progressive Ratio Task, 44 Matching Familiar Figures Test (MFFT), 51 4-Choice Serial Reaction Time Task (4CSRT), Beads Task (BT), 56 High Event Rate Vigilance Task (HERVT), 59 Conners' Continuous Performance Test (CCPT), 48 Iowa Gambling Task 48 and Wisconsin Card Sorting Test (WCST).…”

Rejecting impulsivity as a psychological construct: A theoretical, empirical, and sociocultural argument.

“…These effects on delayed reward discounting seem partially dependent on interactions with the serotonergic system given that the effects of d-amphetamine are lost following depletion of brain serotonin levels (Winstanley et al, 2003). Human laboratory studies have proved more mixed, with some studies reporting similar effects of dopaminergic agents on measures of delay discounting depending on the analytic approach (e.g., de Wit, Enggasser, & Richards, 2002) whereas others have reported null results (Lile et al, 2011;Reed & Evans, 2016;Reed, Levin, & Evans, 2010). This document is copyrighted by the American Psychological Association or one of its allied publishers.…”

The neurobiology of impulsivity and substance use disorders: implications for treatment

“…Interestingly, the NRI atomoxetine has been found to inhibit cue‐induced cocaine self‐administration in mice . Three drug trials in human subjects have been conducted, all with a focus on improving impulsivity in cocaine users . Schmitz et al .…”

“…Another RCT compared modafinil with CBT to CBT alone in crack cocaine users and found no improvement in impulsivity measures . Finally, an open‐label trial was conducted with d ‐amphetamine in cocaine users, but they also found that the drug had no effect on impulsivity . No human studies have yet investigated the effects of NRIs in individuals with stimulant use disorders.…”