A meta-analysis of voucher-based reinforcement therapy for substance use disorders.

AIMS: To systematically investigate the effectiveness of voucher-based reinforcement therapy for the treatment of substance use disorders. METHODS: Effect sizes and 95% confidence intervals were calculated for studies published between January 1991 and March 2004 that utilized voucher-based reinforcement therapy (VBRT) or related monetary-based incentives to treat substance use disorders (SUDs). FINDINGS: Thirty studies involved interventions targeting abstinence from drug use using experimental designs where effects on treatment outcome could be attributed to the VBRT intervention. The estimated average effect size (r) for those studies was 0.32 (95% CI 0.26-0.38). Analyses of variables thought to moderate VBRT effect sizes revealed that more immediate voucher delivery and greater monetary value of the voucher were associated with larger effect sizes. Additional studies were identified wherein VBRT was used to target clinic attendance (n = 6) or medication compliance (n = 4). VBRT studies targeting attendance produced average effect sizes of 0.15 (95% CI 0.02-0.28), while those that targeted medication compliance produced an average effect of 0.32 (95% CI 0.15-0.47). No significant moderators were identified for these 10 studies. CONCLUSIONS: Overall, VBRT generated significantly better outcomes than did control treatments. These results further support the efficacy of VBRT, quantify the magnitude of its effects, identify significant moderators and suggest potential directions for future research.

Influence of the duration of abstinence on the relative reinforcing effects of cigarette smoking.

RATIONALE: Sustaining smoking abstinence during the initial weeks of a cessation effort is highly correlated with long-term smoking abstinence. However, experimental research is needed to establish a direct causal relationship between achieving early abstinence and lowered relapse risk. OBJECTIVE: In the present study, we tested whether a period of sustained abstinence directly decreases the relative reinforcing effects of cigarette smoking. METHODS: Participants were 63 adult smokers who were randomized into one of three conditions: 14-day (14C), 7-day (7C), and 1-day (1C) contingent payment for smoking abstinence. Smoking status was assessed three times per day for 14 consecutive days using breath carbon monoxide monitoring and an abstinence criterion of < or = 4 ppm. In the 14C condition, monetary payment was contingent on abstinence for all 14 days; in the 7C condition, payment was noncontingent for days 1-7 and contingent for days 8-14; in the 1C condition, payment was noncontingent for days 1-13 and contingent for day 14. On day 14, all participants completed a 3-h preference session under controlled laboratory conditions wherein they could make a maximum of 20 exclusive choices between options to smoke (two puffs/choice) or earn money (0.25 dollars/choice). Preference was deemed an index of the relative reinforcing effects of smoking and money. RESULTS: A significantly lower proportion of participants in the 14C condition ever chose the smoking option (19%) compared to those in the 7C (57%) or 1C (62%) conditions. CONCLUSIONS: These results provide experimental evidence that sustained abstinence can decrease the relative reinforcing effects of smoking, an effect that may be related to the commonly observed decrease in relapse risk among those who are able to sustain smoking abstinence during the initial weeks of a cessation effort.

An experimental test of the influence of prior cigarette smoking abstinence on future abstinence.

Significant positive associations between early and later abstinence are often reported in clinical trials on smoking cessation, but those relationships do not permit causal inferences. The present study was conducted to examine experimentally whether prior smoking abstinence histories can directly facilitate later abstinence, using a contingency management procedure to manipulate prior abstinence. A total of 40 adult cigarette smokers who were not trying to quit were randomly assigned to one of two conditions: Contingent ALL (C-ALL), who earned monetary incentives contingent on smoking abstinence during three 5 day experimental periods; or Contingent LAST (C-LAST), who earned incentives independent of abstinence during the first two periods (i.e., noncontingent payments) and contingent on abstinence during the final period. The contingency management procedure was effective in establishing different abstinence histories in the two conditions during the first two periods. Comparison of abstinence levels between the C-ALL and C-LAST conditions during the third period showed significantly greater abstinence in the C-ALL condition, although nicotine withdrawal and other subject ratings generally did not differ significantly between the two conditions. These results provide experimental evidence that prior abstinence histories can directly influence subsequent efforts to abstain from smoking.

Clinical implications of reinforcement as a determinant of substance use disorders.

Extensive scientific evidence indicates that reinforcement plays an important role in the genesis, maintenance, and recovery from substance use disorders. In this chapter, we review recent clinical research from laboratory, clinic, and naturalistic settings examining the role of reinforcement in substance use disorders. Well-controlled human laboratory studies are reviewed characterizing orderly interactions between the reinforcing effects of drugs and environmental context that have important implications for understanding risk factors for substance use disorders and for the development of efficacious interventions. Recent treatment-outcome studies on voucher-based contingency management and community reinforcement therapy are reviewed demonstrating how reinforcement and related principles can be used to improve outcomes across a wide range of different substance use disorders and populations. Overall, the chapter characterizes a vigorous area of clinical research that has much to contribute to a scientific analysis of substance use disorders.

A pilot study on voucher-based incentives to promote abstinence from cigarette smoking during pregnancy and postpartum.

We report results from a pilot study examining the use of vouchers redeemable for retail items as incentives for smoking cessation during pregnancy and postpartum. Of 100 study-eligible women who were still smoking upon entering prenatal care, 58 were recruited from university-based and community obstetric practices to participate in a smoking cessation study. Participants were assigned to either contingent or noncontingent voucher conditions. Vouchers were available during pregnancy and for 12 weeks postpartum. In the contingent condition, vouchers were earned for biochemically verified smoking abstinence. In the noncontingent condition, vouchers were earned independent of smoking status. Abstinence monitoring and associated voucher delivery was conducted daily during the initial 5 days of the cessation effort, gradually decreased to every other week antepartum, increased to once weekly during the initial 4 weeks postpartum, and then decreased again to every other week for the remaining 8 weeks of the postpartum intervention period. Contingent vouchers increased 7-day point-prevalence abstinence at the end-of-pregnancy (37% vs. 9%) and 12-week postpartum (33% vs. 0%) assessments. That effect was sustained through the 24-week postpartum assessment (27% vs. 0%), which was 12 weeks after discontinuation of the voucher program. Total mean voucher earnings across antepartum and postpartum were 397 US dollars (SD=414 US dollars) and 313 US dollars (SD=142 dollars) in the contingent and noncontingent conditions, respectively. The magnitude of these treatment effects exceed levels typically observed with pregnant and recently postpartum smokers, and the maintenance of effects through 24 weeks postpartum extends the duration beyond those reported previously.

Environmental enrichment for the captive spectacled bear (Tremarctos ornatus).

As part a series of investigations of environmental enrichment methods for zoo animals, two spectacled bears (Tremarctos ornatus) were observed for 40 h, documenting use of cage space and behaviors, using a detailed ethogram. Baseline data showed concentration of activity into limited areas of the enclosure and expression of a relatively restricted subset of the species' behavioral repertoire. Introduction of a climbing structure resulted in increased behavioral diversity, both in the use of the enclosure's physical space and the behaviors displayed in various parts of the enclosure.