Stephen T. Higgins

Contingent reinforcement increases cocaine abstinence during outpatient treatment and 1 year of follow-up

This study assessed whether contingent incentives can be used to reinforce cocaine abstinence in dependent outpatients. Seventy cocaine-dependent outpatients were randomized into 2 conditions. All participants received 24 weeks of treatment and 1 year of follow-up. The treatment provided to all participants combined counseling based on the community reinforcement approach with incentives in the form of vouchers exchangeable for retail items. In 1 condition, incentives were delivered contingent on cocaine-free urinalysis results, whereas in the other condition incentives were delivered independent of urinalysis results. Abstinence-contingent incentives significantly increased cocaine abstinence during treatment and 1 year of follow-up compared with noncontingent incentives.

Delay discounting predicts postpartum relapse to cigarette smoking among pregnant women.

Delay discounting (DD), a measure of impulsivity, describes the rate at which rewards lose value as the delay to their receipt increases. Greater discounting has been associated with cigarette smoking and various other types of drug abuse in recent research. The present study examined whether DD predicts treatment outcome among cigarette smokers. More specifically, the authors examined whether baseline discounting for hypothetical monetary rewards predicted smoking status at 24 weeks postpartum among women who discontinued smoking during pregnancy. Participants were 48 pregnant women (10.5 = 4.1 weeks gestational age at study entry) who participated in a clinical trial examining the use of incentives to prevent postpartum relapse. Several sociodemographic characteristics (being younger, being less educated, and reporting a history of depression) assessed at study entry were associated with increased baseline DD, but in multivariate analyses only DD predicted smoking status at 24 weeks postpartum. Greater baseline DD was a significant predictor of smoking status at 24 weeks postpartum. DD was reassessed periodically throughout the study and did not significantly change over time among those who eventually resumed smoking or those who sustained abstinence. The results extend the association of DD with risk for substance abuse to pregnant and recently postpartum cigarette smokers and demonstrate a significant relationship between DD and treatment outcome.

Voucher-based incentives: A substance abuse treatment innovation

In this report we provide an overview of research on the voucher-based incentives approach to substance abuse treatment. This approach was originally developed as a novel method for improving retention and increasing cocaine abstinence among cocaine-dependent outpatients. The efficacy of vouchers for those purposes is now well established, and plans are underway to move the intervention into effectiveness testing in community clinics. The use of vouchers also has been extended to the treatment of alcohol, marijuana, nicotine, and opioid dependence. Particularly noteworthy is that vouchers hold promise as an efficacious intervention with special populations of substance abusers, including pregnant and recently postpartum women, adolescents, and those with serious mental illness. Overall, voucher-based incentives hold promise as an innovative treatment intervention that has efficacy across a wide range of substance abuse problems and populations.

Maternal Smoking and Its Association With Birth Weight

OBJECTIVE: Maternal smoking has been associated with a reduction in newborn birth weight. We sought to estimate how the pattern of maternal smoking throughout pregnancy influences newborn size. METHODS: One hundred sixty pregnant smoking women were enrolled in a prospective study. We collected data on maternal age, education, prepregnancy body mass index, and parity, as well as alcohol and illicit drug use. Cigarette use was defined as self-reported consumption before pregnancy, at the time of study enrollment, and in the third trimester. Statistical analyses were performed based on bivariate correlations and multiple linear regression. RESULTS: Of the smoking parameters examined, maternal third-trimester cigarette consumption was the strongest predictor of birth weight percentile (partial r = –0.23, P < .001). For each additional cigarette per day that a participant smoked in the third trimester, there was an estimated 27 g reduction in birth weight. Prepregnancy smoking volume was not significantly associated with birth weight percentile in bivariate (r = –0.06, P = .47) or multivariable analyses. Additional factors contributing to birth weight include gestational age (partial r = 0.69, P < .001), maternal body mass index (partial r = 0.23, P < .001), and parity (partial r = 0.16, P < .004). In total, these 4 variables explain 61% of the variance in newborn birth weight. CONCLUSION: Maternal third-trimester cigarette consumption is a strong and independent predictor of birth weight percentile. This supports the hypothesis that reductions in maternal cigarette consumption during pregnancy will result in improved birth weight, regardless of the prepregnancy consumption levels. LEVEL OF EVIDENCE: III

Nicotine and caffeine use in cocaine-dependent individuals

Nicotine and caffeine use in 87 cocaine-dependent persons seeking treatment at an outpatient clinic were compared to use of those substances in a matched general population sample (n = 78). The prevalence of cigarette smoking was significantly greater in the cocaine-dependent sample (75% vs. 22%). Within the cocaine-dependent sample, smokers were younger, less educated, employed in lesser skilled jobs, and reported an earlier onset and more frequent use of cocaine. The prevalence of caffeine use was significantly less in the cocaine-dependent group (68% vs. 83%), although, among caffeine users, the cocaine group drank significantly more caffeinated beverages per day than matched controls (4.9 vs. 3.3). Interestingly, regular caffeine use was associated with less frequent cocaine use within the cocaine-dependent sample. To our knowledge, this study is the first to report on prevalence of smoking and caffeine use among cocaine-dependent individuals, and suggests that use of these other substances may influence the onset and pattern of cocaine use.

Initial abstinence and success in achieving longer term cocaine abstinence.

This studys goals were to characterize the relationship between early and longer term cocaine abstinence and assess whether increasing early abstinence increases longer term abstinence. Results from 190 cocaine-dependent outpatients were analyzed. Participants were divided into 2 conditions: (a) those treated with community reinforcement approach (CRA) plus contingent vouchers (n = 125) and (b) those treated with control treatments (n = 65). A period of sustained abstinence during treatment was associated with significantly greater odds of posttreatment abstinence, with no evidence of differences between the 2 treatment conditions in that regard. Treatment conditions differed in that CRA plus contingent vouchers increased the proportion of participants who sustained a period of during-treatment abstinence and increased abstinence during 6-month posttreatment follow-up. Devising interventions that increase the proportion of individuals who achieve an early period of sustained abstinence may be key to increasing longer term cocaine abstinence.

The behavioral economics of concurrent drug reinforcers: a review and reanalysis of drug self-administration research

In economics, goods can function as substitutes, complements, or be independent of one another. These concepts refer to increases, decreases, or no change in the consumption of one item as the price of a second item increases. This review examined whether these economic terms can be used to describe relationships between concurrently available reinforcers in drug self-administration research. Sixteen drug self-administration studies that examined the effects of concurrent reinforcers were identified through a MEDLINE search. Across these studies, the following substances were employed: caffeinated coffee, cocaine, etonitazene, ethanol, heroin, food, methadone, morphine, nicotine cigarettes, pentobarbital, phencyclidine, sucrose and water. These studies were reanalyzed and the results were shown to be consistent with these economic notions. These analyses also showed that relationships among the concurrently available reinforcers were reliable within and across studies, that concurrently available reinforcers can affect each other asymmetrically, and that the relative price may determine the magnitude of effect for substitutes. These findings suggest that these economic concepts may be useful in characterizing the type and magnitude of interactions between concurrently available reinforcers and may suggest potential mechanisms that determine these relationships.

Effects of adding behavioral treatment to opioid detoxification with buprenorphine

This trial assessed whether behavioral treatment improves outcome during a 26-week outpatient opioid detoxification. Thirty-nine opioid-dependent adults were assigned randomly to a buprenorphine dose-taper combined with either behavioral or standard treatment. Behavioral treatment included (a) a voucher incentive program for providing opioid-free urine samples and engaging in verifiable therapeutic activities and (b) the community reinforcement approach, a multicomponent behavioral treatment. Standard treatment included lifestyle counseling. Fifty-three percent of the patients receiving behavioral treatment completed treatment, versus 20% receiving standard treatment. The percentage of patients achieving 4, 8, 12, and 16 weeks of continuous opioid abstinence were 68, 47, 26, and 11 for the behavioral group and 55, 15, 5, and 0 for the standard group, respectively. Behavioral treatment improved outcomes during outpatient detoxification.

Clinical Trial of Abstinence-Based Vouchers and Cognitive-Behavioral Therapy for Cannabis Dependence

Ninety cannabis-dependent adults seeking treatment were randomly assigned to receive cognitive-behavioral therapy, abstinence-based voucher incentives, or their combination. Treatment duration was 14 weeks, and outcomes were assessed for 12 months posttreatment. Findings suggest that (a) abstinence-based vouchers were effective for engendering extended periods of continuous marijuana abstinence during treatment, (b) cognitive-behavioral therapy did not add to this during-treatment effect, and (c) cognitive-behavioral therapy enhanced the posttreatment maintenance of the initial positive effect of vouchers on abstinence. This study extends the literature on cannabis dependence, indicating that a program of abstinence-based vouchers is a potent treatment option. Discussion focuses on the strengths of each intervention, the clinical significance of the findings, and the need to continue efforts toward development of effective interventions.

Influence of an alternative reinforcer on human cocaine self-administration

Identifying factors that modulate cocaine self-administration is fundamental to the development of effective strategies to treat and prevent cocaine abuse. In the present study, the influence of an alternative reinforcer on the probability of cocaine use was examined in four adult humans under controlled laboratory conditions. During eleven test sessions, subjects chose between cocaine hydrochloride vs. placebo or between cocaine vs. varying amounts of money (0-