Preliminary Evidence: The Impact of Contingency Management on Depression and Anxiety Among Crack Cocaine Dependent Patients in Brazil


The purpose of the original clinical trial that led to this research was to determine the effect of the treatment method known as contingency management (CM) paired with standard treatment (STCM) compared to standard treatment alone (STA) in a group of crack cocaine dependent participants in Sao Paulo, Brazil. Our purpose was to examine whether or not this treatment would alter depression and or anxiety in the population while receiving treatment for their crack cocaine use. It was hypothesized that CM would lessen the severity of anxiety and depression in the population while they received treatment for their crack cocaine use as a secondary, indirect effect. Learn more about  how to treat anxiety at Laweekly who recommend the use of the new Delta 8 cartridge.

Literature Review

Crack cocaine has had widespread usage in Brazil for the past 30 years. Most recently an epidemic has occurred in São Paulo, Brazil’s largest city of over 11 million people, where in an inner city community known as “Crackloandia”, hundreds of people are openly using the substance. This epidemic has raised the concern of how to properly address this problem and provide possible resolutions.
Currently this epidemic is known to affect over 2 million users in Brazil, making it the second largest market for crack cocaine in the world when it comes to absolute number of users, accounting for 20% of the global consumption (Narvaez et al., 2014). Using crack cocaine recreationally has been evident since the late 1980’s and the number of users has continued to grow over the years. Most notably, crack cocaine was first detected in Brazil inside abandoned and run-down neighborhoods neglected by public services. The increasing uses of these areas have led to recognizable focal points for substance use, referred to as “cracklands” by locals (Ribeiro et al., 2014). Demographically this epidemic has mainly affected young adults of age 18-24. According to the Brazilian National Alcohol and Drugs Survey, 1.5% of Brazilians 14 years or older have smoked crack at least once during their lifetime, while over 0.8% of this population has used the drug in the past year (Miguel et al., under revision).
The significance of this problem has relevance not only regarding the direct medical and behavioral consequences involved with abuse of crack cocaine, but the societal and economic implications are staggering. Crack cocaine is one of the most addictive substances known, while users develop dependence on the substance much sooner than other drugs. Importantly, crack users develop dependence faster and with a more compulsive pattern of use when compared to those who snort cocaine (Miguel et al., under revision) or use other stimulants like nicotine or methamphetamine. Moreover, crack being the free base form of cocaine has been noted to cause more mental health problems than cocaine powder, magnifying existing risks already associated with use of this dangerous substance (Haasen et al., 2005). For some, detoxification can even be deadly. Twenty-one percent of 131 crack users hospitalized for detoxification between 1992 and 1994 died, making this one of the highest mortality rates for crack cocaine users in the world at that time (Ribeiro et al., 2004). Furthermore, the use of crack cocaine has been associated with risky sexual behaviors resulting in a greater susceptibility to sexually transmitted diseases. The prevalence of HIV in inner-city communities across the United States similar to those in São Paulo Brazil has been 2.4 times higher among crack users in comparison with nonsmokers (Edlin et al., 1994). In Brazil, data indicated that more than a third of crack users (39.5%) reported not having used a condom during vaginal intercourse in the month prior (Narvaez et al., 2014). In addition, for many women, sex is used as a means of exchange to obtain the drug too (17.8%), which often results risky sexual behavior too across multiple partners (Narvaez et al., 2014). Yearly STD testing should be done as suggested by pregnancy resource center.
Analyzing past drug policy in Brazil suggests there to be a lack of scientific research to invoke the need for intervention. Treatment centers and detoxification centers are necessary interventions to reduce the population of those who are dependent on crack cocaine. In the past, Brazil has lacked in their provision of an adequate number of detoxification centers for individuals with substance abuse disorders, making it complicated to combat and assist the growing population of crack users in Brazil (Ribeiro et al., 2014). Other efforts have been made in the past by smaller local church communities by providing housing and food for patients so long as they are sober. Although current drug policy in Brazil is said to be in much better shape than it was 30 years ago, the process of improvement can be slow due to the inability of the government to manage resources well and finance these institutions adequately (Ribeiro et al., 2014).
Current research is being done to test the efficacy of various approaches to treating patients who are addicted to crack cocaine in São Paulo. These approaches are an attempt to prolong periods of abstinence through various treatment modalities. One of recently tested behavioral treatments is contingency management, which is known to be one of “the most effective treatments for substance use disorders” (Miguel et al., p. 5). Contingency management involves the distribution of incentives in exchange for crack cocaine negative urine sample provision to promote abstinence. In Sau Paulo, when contingency management was coupled with standard treatment and compared to standard treatment alone, patients who received incentives for remaining sober were “8.57 times more likely to achieve at least 4 weeks of continuous abstinence” (Miguel et al., p. 14). This new research suggests the possibility of more effective treatment options for treating this epidemic than those that have been exhausted in the past.
The previous study based off the same trial examined the efficacy of CM using the same STCM and STA groups. It was then seen that those treated with CM tended to have a better post treatment disposition with lower Depression and Anxiety inventory scores. This is important because it suggests that the possible magnitude of illnesses that CM is capable of treating may be broader than substance disorders. The significance of this is central to the realm of disease treatments available today, not only in Brazil but in the United States and elsewhere, and their effectiveness not only in crack cocaine patients but in patients who suffer from other abuse disorders as well. This work has taken a deeper look into the data dealing with the depression and anxiety levels in each group for the trial.


The current study is based off a preliminary data set taken from a larger randomized clinical trial stratified for alcohol dependence (Miguel et al., under revision). All data for the clinical trial was collected from 45 individuals seeking treatment for crack cocaine use disorder from a disenfranchised region of Sao Paulo. Upon intake, all participants were interviewed and completed the Beck depressive inventory and Beck anxiety inventory. The Beck depression inventory consists of 21 questions, all multiple choice, as a means to obtain a measurement of each patient’s depressive symptoms. The same is true of the anxiety inventory – it is intended to measure each patient’s anxiety symptoms. Treatment lasted for 12 weeks; patients were randomized to receive either Standard Treatment plus Contingency Management (STCM) or Standard Treatment Alone (STA). STA entailed up to 4 hours a week of group meetings, occupational therapy, one-on-one individual sessions, and psychotherapy.
The STCM group received the same treatment with the exception that they received incentives for remaining abstinent. The value of the incentives was distributed as follows; R$5.00 (Brazilian monetary coin) for the first negative crack cocaine sample, incentives increased in value of R$2.00 for every successive crack cocaine negative sample; if patients tested negative for crack cocaine an additional R$2.00 could be added for a negative alcohol breath sample. Patients received an extra R$20.00 for remaining abstinent throughout the week, and another R$10.00 for testing negative for alcohol and THC in the same week. If patients were to test positive for crack cocaine during any appointment or were absent they would receive no incentive and the value would reset back to R$5.00. Once all treatment was complete, all participants were to once again fill out the Beck depressive and anxiety inventory. Our analyses examined the Beck depression and anxiety index value to be compared from pre to post treatment and we compared this change in the outcome over time between the two randomized groups. CM was administered exactly the same in both groups making for a controlled variable and both groups were interviewed and tested in the same manner before, during, and after the twelve-week treatment plan.



We found that the STCM group had a better response to treatment with regards to a reduction in overall depression and anxiety. (Figure 1 & 2)
Figure 1 & 2. Average of the differences in Beck Depression/Anxiety scores between pre and post treatment for the control group (Standard Treatment Alone) and the Standard Treatment plus Contingency Management (STCM) group.
In addition to the information presented above, further analysis was performed to better establish the distinction in depression and anxiety scores between the two groups. After running an independent samples t-test on the preliminary data set for pretreatment we found that at time one STA and STCM were homogenous with respect to the relative condition of their depression levels (z= 11.003 STA, z=10.286 STCM, p<.025). Although when it came to anxiety both groups were not homogenous at time one (z= 16.431 STA, z=11.532, p>.05). It was important to note that though they were not homogenous before treatment for this category, anxiety scores were higher for the experimental group (=19 STA, = 25.714 STCM). This suggests the experimental group had greater margin for improvement. An independent paired sample t test distinguished our results for the two group’s overtime. For the anxiety the STCM group showed a significant drop in scores (p<.005) whereas STA showed a less significant drop in anxiety scores (p>.15). As for depression the trend is the same, STCM (p<.005), STA (p>.25). Therefore, we can say that based off the preliminary data set, standard treatment plus contingency management was more effective at reducing depression and anxiety scores in patients than standard treatment alone. Whether this suggests that STCM actually reduces depression and anxiety in patients is dependent on how effectively the beck depression and anxiety inventories accurately portray a patient’s psychological condition.


The findings of this study, that CM effectively reduces depression and anxiety scores in patients who abuse crack cocaine in the city of Sao Paulo, Brazil, supports our hypothesis that CM would lessen the severity of anxiety and depression in the population while they received treatment for their crack cocaine use as a secondary, indirect effect. This was true even given that in terms of Anxiety levels, the STCM group had more room for improvement based of pretreatment analysis.
The implications of this research find it likely that CM is a treatment option capable of treating patients with a comorbidity of anxiety, depression, and substance abuse disorders. Co-occurring alcohol use disorders and anxiety disorder have been expressed as a real concern amongst people throughout the world, and the need for treatment interventions that are adapted to target this unique condition are urgent (Smith J, Randall C, 2012)
Although these findings cannot express the outcome of CM as an intervention for substances other than crack cocaine, future research should take a broader look at the implications of CM and examine its efficacy in the case of multiple substances; especially those most associated with depression and anxiety comorbidities as an additional characteristic of treatment. Furthermore, it should be the objective of forthcoming literature to establish the progression of comorbidities involving substance abuse and anxiety and/or depression disorders, and to ascertain whether or not substance abuse invokes depression and/or anxiety or vice versa. This will help to better target the cause of a patient’s illness and formulate a treatment that is more specific to the patient’s needs. Moreover, it is logical that the effectiveness of treating such comorbidities as cases well correlated and contingent upon another would be greater than treating them as separate.