Oral drug self-administration in rhesus monkeys: interactions between drug amount and fixed-ratio size.

During daily 3-hr sessions, 5 rhesus monkeys drank drug solutions and water that were concurrently available. The drug solutions were: 1 milligram per milliliter (mg/mL) pentobarbital (2 monkeys), 1 mg/mL pentobarbital plus 0.5% ethanol (1 monkey), 1 mg/mL pentobarbital plus 1% ethanol (1 monkey), and 8% ethanol (1 monkey). The drug solution and water were available under identical two-component tandem fixed-ratio continuous-reinforcement N schedules. Two variables were manipulated: the size of the fixed-ratio component and the number of liquid deliveries (N) in the second component. Deliveries of the drug solution maintained higher rates of responding than did deliveries of the drug vehicle, water. The number of drug deliveries per session increased with increases in the number of deliveries per fixed ratio and decreased with increases in fixed-ratio size. Analysis of the results in terms of the proportion of deliveries to responses showed that the number of drug deliveries per session was directly related to the size of this quotient. Finally, when fixed-ratio size was repeatedly doubled, the following orderly relationship emerged: The greater the number of available drug deliveries per fixed ratio, the less was the percent decrease in the number of fixed ratios completed per session. It was concluded that increases in the number of liquid deliveries per fixed ratio resulted in increases in reinforcing efficacy.     

Reliability of drug use responses in a longitudinal study

In a prospective longitudinal study of adolescents' drug use, the trustfulness of the self-reports about drug use was investigated by means of a test for logical consistency. A sample of 1936 high school students completed a written survey in the fall of 1987 and again in spring 1988, seven to eight months later. The findings indicate that the information obtained is logically consistent at one particular point in time. Analyses show, however, that the consistency drops somewhat over time. The legal drug use responses show the highest consistency, the answers regarding hard drugs like amphetamine and heroin show the least favourable consistency, with cannabis and inhalants somewhere in the middle. There seem to be two main reasons for the inconsistent answers: some respondents wilfully underreport their drug consumption. This seems partly to be a function of the level of illegality of the drug. However, poor memory and episodic uses of such drugs seem also to be important. Generally this study agrees with other studies and indicates an overall relatively high level of longitudinal consistency regarding drug use responses. This kind of survey must therefore be regarded as a relatively reliable instrument in collecting information regarding drug use.     

CONTINGENCY MANAGEMENT INTERVENTIONS: EFFECTS ON TREATMENT OUTCOME DURING METHADONE DETOXIFICATION

We examined the effectiveness of a contingency management program in preventing relapse to illicit opiate use and increasing treatment retention during outpatient methadone detoxification treatment. Twenty male opiate addicts were randomly assigned to an experimental or control group. Following a 3-week methadone stabilization period, men in both groups received identical gradual methadone dose reductions during Weeks 4 through 9 and were maintained on placebo during Weeks 10 through 13. Beginning in Week 4, control patients received $5.00 for providing a specimen twice weekly. Experimental patients received $10.00 and a take home methadone dose for each opiate-free urine specimen but forfeited the incentives and participated in more intensive clinic procedures when specimens were opiate positive. The contingency management procedure slowed the rate of relapse to illicit opiate use. Experimental patients provided significantly more opiate-free urines during the methadone dose reduction in Weeks 4 through 9 than control patients, although the difference between groups was no longer significant during placebo administration in Weeks 10 through 13. In addition, the contingency management program improved treatment retention and reduced symptom complaints during the detoxification. The usefulness and limitations of contingency management procedures for outpatient methadone detoxification are discussed.     

Effects of situational demand in the role-play assessment of assertive behavior

Assertive and nonassertive subjects role played responses to interpersonal situations of known response difficulty in which various types of assertions were appropriate to evaluate the interactive effects of demand and difficulty on assertive performance. Subjects responded as they normally would (low demand) and as if they had just finished an extensive assertive training program (high demand). Role-play data, rated for overall assertion, revealed that (a) subjects were more assertive under high than low-demand; (b) assertive performance varied with situational difficulty; and (c) self-reports of assertive ability predicted behavior only when role-play situations were easy or demand low, and high demand had preceded low demand. It was concluded that assertive performance is strongly influenced by situational and cognitive variables, that self-reports predict behavior only in specific assessment circumstances, and that role plays tend to measure maximal, rather than typical, performance. These findings are discussed in terms of their implications concerning the validity of role-play assessment procedures.An earlier version of this paper was presented at the annual convention of the Association for Advancement of Behavior Therapy, Toronto, Canada, November 1981.     

THE RELATIVE EFFICACY OF METHYLPHENIDATE (RITALIN) AND BEHAVIOR-MODIFICATION TECHNIQUES IN THE TREATMENT OF A HYPERACTIVE CHILD

Drug versus placebo effects were contrasted with those of contingency management in the treatment of a hyperactive child. Several criterion behaviors were monitored in two different settings to gauge the breadth and generalizability of drug and behavior-management effects. Medication and contingency management effects were both found to be situation specific. No interaction effects were found. Accuracy of task performance, amount of eye contact with the experimenters, frequency of repetitive hand movements, and distractible behavior were apparently unaffected by medication (Ritalin versus placebo) within the clinic. A multiple-baseline design incorporating contingency reversals revealed the reinforcement contingencies to be the crucial variable controlling behavior within the clinic. Medication effects were shown to be significant within the home setting where reinforcement contingencies were not changed. While aggressive behavior decreased as a function of Ritalin, repetitive hand movements increased.     

THE ACCELERATED INTAKE: A METHOD FOR INCREASING INITIAL ATTENDANCE TO OUTPATIENT COCAINE TREATMENT

We examined whether offering an accelerated (same-day) versus a standard (1- to 7-day delay) intake appointment increased initial attendance at an outpatient cocaine treatment program. Significantly more of the subjects who were offered an accelerated intake (59%) attended than those who were given a standard intake (33%), χ² (2, N = 78) = 4.198, p < .05. The accelerated intake procedure appears to be useful for enhancing enrollment in outpatient addiction treatment.     

The long-term outcome of a personal network-oriented HIV prevention intervention for injection drug users: The SAFE study

Social influence processes have been found to affect numerous drug and health-related behaviors. We postulated that by using a network-oriented intervention it may be possible to capitalize on social influence processes to reduce human immunodeficiency virus (HIV) risk behaviors. The present study used an experimental study design for delivering a psychoeducational acquired immunodeficiency syndrome (AIDS) preventive intervention to injection drug sharing networks. Participants were recruited from the ALIVE study, an epidemiological study in Baltimore. In the present paper we examine the self-reported behavioral outcomes of 117 injection drug users 18 months after the baseline interview. HIV seronegative experimental participants reported significantly less frequent needle sharing and less injecting of heroin and cocaine than controls. In multiple logistic regression models of HIV seronegative participants, there was a significant negative association between assignment to the experimental group and the HIV-related behaviors of needle sharing and sharing of cookers in the prior 6 months; controls were 2.8 times more likely than experimentals to report needle sharing and were 2.7 times more likely to report sharing cookers. The results of this 18-month follow-up suggest that among injection drug users network-oriented interventions may be a promising approach to HIV prevention.     

participating in a couples therapy outcome study: Participants' views

Discovering that participants who received therapy in a research project and were being debriefed in a therapy outcome study considered those assessment sessions therapeutic, the authors conclude that participants: (a) are aware of the research context, (b) have some idea about how it affected the treatment they got, and (c) see positive outcomes for taking part in the study. Assessment and treatment were not separated in the minds of some participants, as they had been in the mind of the researchers.This study was supported in part by National Institute on Drug Abuse grant #1R 18DA 1069232001.     

Unit-price analysis of opioid consumption by monkeys responding under a progressive-ratio schedule of drug injection.

Several reports have indicated that drug consumption in self-administration procedures is a function of the ratio of the instrumental requirement to the dose of drug, a quantity termed unit price. We evaluated three predictions from this unit-price model in a reanalysis of data on opioid self-administration in rhesus monkeys responding under a progressive-ratio schedule (Hoffmeister, 1979). We evaluated whether consumption was inversely related to unit price, and compared the goodness of fit of an equation devised by Hursh, Raslear, Shurtleff, Bauman, and Simmons (1988) to that of a linear model predicting consumption as a function of dose. We also tested whether consumption was constant when the same unit price was comprised of different combinations of dose and instrumental requirement. Consumption declined overall as unit price increased. The equation devised by Hursh et al. and the linear model based on dose fit the data equally well. Drug consumption was not uniform at a given unit price. The analyses suggest limits on the unit-price model as a characterization of drug consumption.     

Normalized demand for drugs and other reinforcers.

The concepts of behavioral economics have proven to be useful for understanding the environmental control of overall levels of responding for a variety of commodities, including reinforcement by drug self-administration. These general concepts have implications for the assessment of abuse liability and drug abuse intervention and the formulation of public policy on drug abuse. An essential requirement is the ability to compare the demand for different drugs directly in order to assess relative abuse liability, and to compare demand for the same drug under different environmental and biological interventions to assess their ability to reduce demand. Until now, such comparisons were hampered by the confounding effect of varying drug doses and potencies that prevent quantitative comparisons of demand elasticity--sensitivity of consumption and responding to the constraint of price (effort). In this paper we describe a procedure to normalize demand-curve analysis that permits dose- and potency-independent comparisons of demand across drugs. The procedure is shown to be effective for comparing drug demand within and across the drug classes. The technique permits a quantitative ordering of demand that is consistent with the peak levels of responding maintained by the drugs. The same technique is generalized for the comparison of other types of reinforcers under different biological conditions.