| Summary: | Background: Heroin addiction is an extremely prevalent problem worldwide, and in Britain is commonly treated with methadone maintenance therapy. Previous literature has examined the neuropsychological impact of opioids such as heroin and methadone and points to a detrimental effect on neuropsychological functioning. However no attempt has been made to examine and compare the impact of these opioids on the same group of individuals. This study aims to measure the neuropsychological functioning of a group of opiate dependent males while actively using heroin and again once maintained on prescribed methadone. As previous research has been complicated by the effects of head injury and/or concurrent substance/alcohol dependence, the presence of these factors is used as exclusion criteria. Method: Neuropsychological functioning was assessed in a cohort of 14 opiate dependent males while actively using heroin, using the Repeatable Battery for the Assessment of Neuropsychological Status. The same measure was repeated with the ten members of the original cohort who successfully progressed to methadone maintenance. In order to identify any neuropsychological impairment, participants' level of functioning while using heroin and while using methadone was compared to an estimate of their premorbid intellectual functioning. Quantitative statistical analyses were used to determine whether results were statistically significant. Results: Participants performed significantly below the level predicted by their estimate of premorbid intellectual functioning both while using heroin and while using prescribed methadone. There was no significant difference in the participants' neuropsychological performance while using heroin and while maintained on a daily prescription of methadone. Discussion: The results of the present study support previous research which has demonstrated a link between heroin and methadone use and neuropsychological impairment. Previous literature has not directly compared the neuropsychological performance of heroin users with opioid addicts maintained on a daily methadone dose. The present study found no significant differences between the performances of the group while using heroin and once maintained on methadone. These findings have important implications for clinical practice in the field of addictions. There are a number of challenges associated with recruiting and retaining participants in the context of opioid addiction research, which are discussed in detail. The limitations of this study are explored, and future directions for research in this area are considered.
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