The Effect of Drug Abstinence Program on Memory Functioning of Heroin Addicts

Introduction: Most of our knowledge regarding the link between opioid dependence and poor cognitive functioning is derived from cross sectional studies. This longitudinal study measured the change in memory functioning following complete abstinence among individuals with heroin dependence. Methods: Using a before-after design, this study followed 30 adults with heroin dependence from entry to completion of an abstinence program (cold Turkey method). We collected data on demographic factors and drug use variables. Memory was measured using the Wechsler Memory Scale. Using the paired t test, we compared different domains of memory functioning (i.e. personal information, orientation, mental control, logical memory, number repetition, visual memory, associative learning and memory quotient) before and after abstinence. Results: There was a significant improvement in memory functioning on orientation, mental control, logical memory, number repetition, visual memory, association learning and memory quotient following completion of the abstinence program. The improvement, however, was not statistically significant for memory on personal information. Conclusion: This study documented improvement of memory functioning among heroin dependent adults following complete abstinence (cold turkey method). Further research is needed on the effect of heroin abstinence on memory functioning.


Introduction
The memory function is essential for the performance of daily activities [1,2].Memory is also relevant for drug use treatment programs.Better memory functioning at baseline has been shown to predict better outcomes following drug use treatment [3,4] namely lower relapse and early drop-outs [5].Immediate improvement in memory function following drug treatment is also predictive of long-term drug treatment outcomes [6].
Despite a large body of literature which links opioid dependence to impaired memory functioning [7], it is not clear whether drug use treatment improves memory functioning or not [8].Most studies that have linked drug abstinence to better memory functioning have used cross sectional designs [4,[8][9][10][11][12][13]. Thus, prospective studies are still needed to determine if drug abstinence improves memory functioning or not.
To the best of our knowledge, there is no published evidence in the link between memory functioning when the drug of dependence is heroin [14] and when the abstinence method is cold Turkey.The Cold Turkey Method is defined as "pure" detoxification, without using any medications.In cold Turkey, the person gives up the substance use all at once.That is, rather than gradually easing the process through reduction or by using replacement medication.Although a disadvantage of this method might be severe withdrawal symptoms [15], safety of this method has been shown [16].Cold turkey is being used by people in many parts of the world [16][17][18].
For the first time, when the drug of use is heroin and the method of abstinence is cold Turkey, this study aimed to document the changes in memory functioning following successful abstinence.

Design and Settings
This study is a prospective study conducted in Tehran, Iran in 2008.Data collection was done in the drop-in-centers (therapeutic centers) of Tavalody Dobareh Rehabilitation Center, Tehran, Iran.This center is a non-governmental organization (NGO) for the treatment of substance use, especially opiates.It has treatment centers in 21 provinces out of the total 32 provinces of the country.This center is the most active center for the cold Turkey abstinence of opioids in Iran.

Codes of Ethics
All participants signed an informed consent.The ethical board of the National University of Malaysia approved the study.

Participants and Sampling
A total number of 30 participants with heroin dependence were enrolled.Drug dependence was defined according to the Diagnostic and Statistical Manual of Mental Disorders -IV (DSM-IV) criteria [19][20][21][22][23].To obtain a representative sample of all attendants of the Tavalody Dobareh Rehabilitation Center, we used a simple random sampling strategy from new entries.Each month, about 40 new patients are being recruited to the treatment, from these, most are men, and most are heroin dependents, and the most widely used treatment is cold Turkey.All new clients were given a 4 digit code which was used for sampling in this study.We selected the participants using computer generated random numbers.

Procedure
In this study, complete and successful drug abstinence was defined as the state of refraining from drug use completely (a drug free state) [24].Here, successful abstinence was defined after 4 weeks of heroin abstinence.

Measures and Measurements
In this study, data were collected via interviews.All interviews were done by a single psychologist (SA).Data included socio-demographic data (gender, age, educational level, and marital status), drug use data (person who suggested for first use, first drug and substance) and overall health.

Main Outcome
The Wechsler Memory Scale (WMS) was also completed before and after complete abstinence.The WMS includes verbal and visual learning tests by means of association and matching, memory of excerpts, drawings and the identification of visual spatial information previously presented.Memory is assessed in terms of both immediate and delayed recall.The WMS provides global values for general, verbal and visual short-and long-term memory, as well as for attention and concentration.Specific functionality is evaluated in the verbal areas of logical memory and associative learning with verbal pairing (immediate and delayed) along with the visual areas of memory of image, learning associated with visual stimuli (immediate and delayed) and visual reproduction of pictures (immediate and delayed), as well as the areas of mental concentration, numeric span and visual memory.Comparison of the index of attention/concentration with the general index of memory on the WMS provides a means of distinguishing between disorders of concentration and those of memory.WMS is highly accurate at classifying severely impaired and unimpaired subjects in terms of memory but is less accurate at discriminating mild and moderate impairment [25][26][27][28].

Statistical Analysis
The paired samples t-test was used for data analysis to assess the effect of heroin abstinence on memory scores on personal information, orientation, mental control, logical memory, number repetition, visual memory, association learning and memory quotient.We used SPSS 14 for data analysis, and a level of P less than .05was considered significant.

Results
Participants were all men.Table 1 shows sociodemographic and drug related characteristics The paired t test showed that memory functioning subscales namely orientation, mental control, logical memory, number repetition, visual memory, association learning and memory quotient significantly improved after complete abstinence of heroin dependency.Personal information showed only a marginal significant improvement (Table 2).

Discussion
According to our findings, individuals with heroin dependence undergoing opioid withdrawal regimes unassisted by opioid substitution treatment or withdrawal symptom alleviation show improved memory function in multiple domains.Thus, complete abstinence from heroin dependence disorder may improve most areas of memory functions (i.e.orientation, mental control, logical memory, number repetition, visual memory, association learning and memory quotient) even when the method is cold Turkey.This study adds to the literature regarding the effects of detoxifying opiate addicts on cognitive functioning [8], in the case of heroin [4].The result of this study was unique as heroin was the drug of dependence and cold Turkey was the method of abstinence.We could not find any previous similar studies.
Literature has shown that patients at entry of opiate detoxification programs present with cognitive impairments to varying degrees of severity [7].Opiate abusers show impaired neuropsychological functioning in comparison to matched controls with no history of drug abuse [10].Both methadone-and buprenorphine-treated opioid-dependent patients frequently show cognitive deficits in attention, working memory, and verbal memory [12].According to another study, memory performance of drug users in the abstinence fell between patients under methadone maintenance and controls on many measures suggesting that methadone maintenance may reduce cognitive impairment associated with long-term drug abuse, and some early recovery of neurocognitive functioning may occur during abstinence [29].The same finding has been reported for other drugs such as cocaine [30].
Studies have reported possible mechanisms for the link between memory dysfunction and drug use from which, one is a possible link between cerebral perfusion abnormalities and neuropsychological impairment following chronic substance abuse [31].
New information regarding improvement of memory following drug use treatment has implications for drug abuse treatment policies and practices [32].Thus, the result of our preliminary study is indicative of benefits of heroin dependence treatment programs that use the cold Turkey method.We already know that memory improvement increases the efficacy of opioid treatment programs [3][4][5][6].Thus, the results may contribute to reducing burden of drug use in Iran [33][34][35][36][37][38][39][40][41].

Conclusion
In sum, abstinence of heroin using cold Turkey method may improve memory functioning.Further controlled studies are needed in this regard.

Limitations
Our study had a few limitations.In addition to lack of a control group, it had a small sample size.Physical or psychological health may have confounded the effect of the program on memory functioning in our study.A controlled study is needed to control for the effect of such confounders.

Table 2 .
Comparison of memory function before and after heroin abstinence