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Biomedical subjects

Stephen T Higgins

Publications and source records attributed to Stephen T Higgins.

At least 19 recordsLinked to original sources
PubMed2007

Effects of varying the monetary value of voucher-based incentives on abstinence achieved during and following treatment among cocaine-dependent outpatients.

AIMS: This study examined whether increasing the amount of abstinence achieved during outpatient treatment for cocaine dependence is an effective method for increasing longer-term cocaine abstinence. DESIGN: A two-condition, parallel groups, randomized controlled trial was conducted. SETTING: The trial was conducted in a university-based research clinic. PARTICIPANTS: A total of 100 cocaine-dependent outpatients participated in the trial. INTERVENTION: Participants were assigned randomly to receive treatment based on the community reinforcement approach (CRA) plus voucher-based incentives set at a relatively high monetary value (maximal value = $1995/12 weeks) or CRA with vouchers set at a relatively low monetary value (maximal value = $499/12 weeks). Vouchers were earned contingent on cocaine-negative urinalysis results during the initial 12 weeks of the 24-week outpatient treatment. MEASUREMENTS: Outcomes were evaluated using urine-toxicology testing, questionnaires and other self-report instruments. FINDINGS: Increasing voucher value increased the duration of continuous cocaine abstinence achieved during the 24-week treatment period. Point-prevalence cocaine abstinence assessed every 3 months throughout an 18-month follow-up period was greater in the high- than low-value voucher conditions. The duration of abstinence achieved during treatment predicted abstinence during follow-up, although that relationship weakened over time. CONCLUSIONS: Increasing the value of abstinence-contingent incentives during the initial weeks of treatment appears to represent an effective method for increasing during-treatment and longer-term cocaine abstinence, but the positive association of during-treatment abstinence with longer-term outcome dissipates with time.

Adult↗
PubMed2006

Smoking status in the initial weeks of quitting as a predictor of smoking-cessation outcomes in pregnant women.

OBJECTIVE: Any smoking during the initial 2 weeks of attempting to quit predicts poor short- and longer-term outcomes in the general population of cigarette smokers. The present study examined whether that rule applies to pregnant women. METHODS: Data were obtained from 129 women participating in clinical trials on smoking-cessation examining the efficacy of voucher-based incentives delivered contingent on biochemically-verified abstinence or a control condition wherein incentives were given independent of smoking status. Smoking status was assessed in weeks 1 and 2 of the cessation effort and again at an end-of-pregnancy assessment scheduled at weeks 28-32 gestation using self-report and biochemical verification. RESULTS: Smoking in weeks 1 or 2 predicted smoking at the end-of pregnancy assessment independent of treatment condition. There was a 79% and 92% chance that those who smoked in weeks 1 or 2 would be classified as smokers at end-of-pregnancy in the contingent-incentive and control conditions, respectively. CONCLUSIONS: Clinicians assisting pregnant women trying to quit smoking may want to monitor progress in the initial weeks of the cessation effort and consider enhancing/changing the intervention when smoking is detected.

Adult↗
PubMed2006

Psychological symptoms following smoking cessation in pregnant smokers.

This study examined the relationship between smoking status and psychological symptoms in pregnant women across pregnancy. Participants were 45 women who quit smoking early in pregnancy (early quitters), 22 who quit later in pregnancy (later quitters), and 84 who smoked throughout pregnancy (never quitters). Assessments of smoking status and psychological symptoms (Brief Symptom Inventory and Beck Depression Inventory) occurred near first prenatal visit, second visit, and end of pregnancy. Results indicated that scores on the Global Severity Index of the Brief Symptom Inventory, several Brief Symptom Inventory subscales, and on the Beck Depression Inventory were highest among never quitters, lowest among early quitters, and intermediate for later quitters. Scores decreased across pregnancy, especially between first and second assessments. We found no evidence that quitting smoking increased psychological symptoms either in the immediate post-withdrawal period or later in pregnancy. These findings should temper concerns that quitting smoking may have detrimental psychological consequences during pregnancy.

Adult↗
PubMed2006

Voucher-based contingent reinforcement of marijuana abstinence among individuals with serious mental illness.

Previous studies by our group have used money given contingent on abstinence to reduce drug use by individuals with schizophrenia. In this study, we examined the sensitivity of marijuana use by individuals with serious mental illness to voucher-based contingent reinforcement, which represents the first study to date investigating the efficacy of voucher incentives with this population. This within-subject reversal design consisted of three conditions: 4-week baseline, 12-week voucher intervention, and 4-week baseline. During baseline periods, subjects received 10 US dollars vouchers per urine specimen, independent of urinalysis results. During voucher intervention, only specimens testing negative for marijuana earned vouchers, with total possible earnings of 930 US dollars. Seven adults with schizophrenia or other serious mental illnesses participated in the study. The percentage of marijuana-negative specimens was significantly greater during voucher intervention than during baseline periods. These results provide evidence that marijuana use among individuals with serious mental illness is sensitive to voucher-based incentives and further support the potential feasibility of using voucher-based contingency management to reduce substance abuse in this challenging population.

Adult↗
PubMed2006

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.

Adult↗
PubMed2006

Characterizing nicotine withdrawal in pregnant cigarette smokers.

Maternal smoking is a leading preventable cause of poor pregnancy outcomes and infant morbidity and mortality. Whereas pregnancy has been thought of as a "window of opportunity" when women are more motivated to change health behaviors such as smoking, only 20% of pregnant women quit smoking upon learning they are pregnant and remain abstinent at the end of the pregnancy. Greater understanding of possible obstacles to smoking during pregnancy, such as nicotine withdrawal, is needed. The symptoms of nicotine withdrawal have been well characterized in nonpregnant smokers, but there has been only 1 report conducted during pregnancy, and that was a retrospective study. The aim of the present study was to characterize nicotine withdrawal and craving in pregnant cigarette smokers. These data were collected as part of prospective clinical trials assessing the efficacy of voucher-based incentives to promote abstinence from cigarette smoking during pregnancy and postpartum. The authors examined results from the Minnesota Nicotine Withdrawal Scale (J. R. Hughes & D. K. Hatsukami, 1998) in 27 abstainers (reported no or very low levels of smoking, which was confirmed biochemically) and 21 smokers (smoked at >80% of their baseline smoking level) during the first 5 days of a cessation attempt. Abstainers reported more impatience, anger, and difficulty concentrating than did smokers. The results also suggest that pregnant smokers generally may have elevated baseline levels of withdrawal, which need to be considered in the design and analysis of future studies.

Adult↗
PubMed2006

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.

Humans↗
PubMed2005

Delay discounting in currently using and currently abstinent cocaine-dependent outpatients and non-drug-using matched controls.

Higher rates of delay discounting have been consistently noted in substance abusers compared to non-drug-using matched controls. Additional data from some studies comparing discounting rates in current versus former substance abusers suggest that discounting rates may be adaptable and that drug abstinence may be associated with reductions in discounting. The primary purpose of the present study was to determine whether a period of cocaine abstinence (at least 30 days) resulted in altered discounting rates of money in a population of primary cocaine-dependent patients compared to current cocaine users and non-drug-using matched controls. Results suggest that there was no difference in discounting between currently abstinent and currently using cocaine-dependent outpatients. When these two groups were combined, cocaine-dependent patients showed higher discounting rates than non-drug-using matched controls. These data replicate previous work in cocaine-dependent and other substance abusers compared to non-drug-using controls and suggest that a longer period of abstinence may be required to modify discounting in this population.

Adult↗
PubMed2005

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.

Adult↗
PubMed2005

Methylphenidate increases cigarette smoking.

RATIONALE: Methylphenidate (Ritalin) and d-amphetamine (Dexedrine), stimulants commonly prescribed for behavioral problems associated with attention deficit hyperactivity disorder (ADHD), produce a similar constellation of behavioral effects. The results of previous studies suggest that d-amphetamine increases rates of smoking and the reinforcing effects of smoking. The effects of methylphenidate on smoking have not been assessed although it is the most commonly prescribed pharmacotherapy for ADHD and individuals with ADHD are at increased risk for smoking. OBJECTIVE: In this experiment the acute effects of a range of doses of methylphenidate (5, 10, 20, and 40 mg) and placebo were assessed in ten cigarette smokers who were not attempting to quit and were without ADHD or other Axis I psychiatric disorders. METHODS: Each dose of methylphenidate was tested once, whereas placebo was tested twice. One hour after ingesting drug, participants were allowed to smoke ad libitum for 4 h. Measures of smoking included total cigarettes smoked, total puffs, latency to the first cigarette, and carbon monoxide levels. Snacks and decaffeinated drinks were available ad libitum, and caloric intake during the 4-h smoking session was calculated. RESULTS: Methylphenidate dose dependently increased the total number of cigarettes smoked, number of puffs, and carbon monoxide levels. As expected, methylphenidate dose dependently decreased the number of food items consumed and caloric intake. CONCLUSIONS: The results of this experiment suggest that methylphenidate, like d-amphetamine, increases rates of cigarette smoking.

Adolescent↗
PubMed2005

Characterizing and improving HIV/AIDS knowledge among cocaine-dependent outpatients.

The present study was an experimental test of efficacy of a brief education intervention for increasing HIV/AIDS knowledge among cocaine-dependent outpatients. Participants were randomly assigned to an HIV/AIDS education intervention (experimental condition) or a sham intervention (control condition). Control participants were subsequently crossed over to the HIV/AIDS education intervention. Experimental participants had higher scores on tests of HIV/AIDS knowledge after receiving the education intervention than did control participants. Further supporting the intervention's efficacy, control participant scores also increased once participants were crossed over and received the education intervention. Scores at follow-up were lower than at postintervention but remained higher than baseline scores. Results support the intervention's efficacy for increasing HIV/AIDS knowledge among cocaine-dependent outpatients. This intervention is brief, inexpensive, and easily implemented.

Cocaine-Related Disorders↗
PubMed2005

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.

Adult↗
PubMed2004

Examining interrelationships between abstinence and coping self-efficacy in cocaine-dependent outpatients.

Initial abstinence and self-efficacy predict treatment outcome in cocaine-dependent outpatients. Associations between abstinence and coping self-efficacy were examined among cocaine-dependent outpatients (N=126). Abstinence was verified by urinalysis. Coping self-efficacy was measured using a modified Situational Confidence Questionnaire (SCQ). The modified SCQ had good validity and reliability, and scores increased during treatment. In bivariate analyses, early abstinence and SCQ scores each predicted subsequent abstinence and confidence during treatment and posttreatment follow-up. Based on structural equation modeling, early confidence was a significant predictor of later confidence but not of later abstinence, whereas early abstinence was a significant predictor of later abstinence and confidence. Results suggest a unidirectional relationship wherein prior abstinence predicts subsequent abstinence and confidence.

Adult↗
PubMed2004

An experimental examination of the initial weeks of abstinence in cigarette smokers.

Gaining experimental control over abstinence may help define processes that change during abstinence that may be related to the association between initial abstinence and relapse risk often noted in clinical trials. Adult smokers (n = 34) were randomly assigned to receive monetary incentives contingent on abstinence (CO +/- 4 ppm) or noncontingent for 12 days. Carbon monoxide (CO) tests were conducted 3 times per day, saliva samples were collected on Days 5 and 12, and all other measures were collected 1 time per day. In the contingent group, 59% of participants abstained throughout the study versus 0% in the control condition. Abstinence was associated with increases in participant-rated ease of abstaining and confidence in abstinence; nicotine withdrawal severity and craving decreased over time. Results indicate that it is feasible to experimentally manipulate smoking abstinence and that doing so can enhance understanding of the relationship between early abstinence and relapse risk.

Adult↗
PubMed2004

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.

Adolescent↗
PubMed2004

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.

Adult↗
PubMed2004

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.

Humans↗