Neurobiology of cognition and craving in opiate addiction: implications for relapse

Drug addiction is a serious social problem, placing a burden on health and social services as well as the criminal justice system. Although only a minority of addicts use heroin, it is associated with some of the most significant health and social costs of drug misuse. Effective treatments of drug addiction have proved elusive. One major reason for this is that although many addicts can overcome their addiction for a short period of time, their craving for opiates continues and leads to most relapsing in the long term. This research will investigate the brain mechanisms of craving and cognition in recently abstinent opiate addicts. It will also determine whether differences in brain function can predict whether individual addicts will relapse after discharge from a treatment programme. If key differences can be identified, this could provide the basis for the development of more effective treatments. We will provide information about our findings to the media, to users groups and on our website.

High rates of relapse are a key challenge in the treatment of opiate addiction. This proposal aims to bring new clinical and neuroscientific expertise to bear on the problem of understanding and preventing relapse. The initial aim is to establish the collaboration and to identify brain mechanisms that are associated with risk of relapse in recently de-toxified heroin addicts. Participants will be exposed to a video that reliably elicits subjective craving, during MRI scanning. Our novel phMRI analysis methods will enable us to follow the direct effects of craving on regional brain function for 15 minutes and then investigate how craving modulates cognitive function. The cognitive tasks will be chosen to challenge key processes implicated in addiction and risk of relapse; behavioural inhibition, cognitive control and decision-making. 40 opiate addicts will be recruited from an inpatient treatment programme and will be scanned as they complete the programme, just prior to discharge. At this stage, subjects will be abstinent from drugs and not taking maintenance medications. Subjects will be scanned twice at an interval of 48-72 hours to compare the effects of a craving video with a neutral video. A group of matched control subjects will be scanned using the same protocol. This will allow us to identify neuronal correlates of acute craving in opiate addicts, and the modulation of cognitive function by craving. The detoxified addicts will be monitored for 3 months following discharge from treatment to determine whether or not they relapse within this period. Based on experience and previous literature we anticipate a relapse rate of 50-70%. We will perform a post-hoc comparison between relapsing and abstinent patients to determine whether any of the neuronal indices represent potential biomarkers for relapse. This research will provide a basis for the use of imaging and cognitive biomarkers to detect the efficacy of novel pharmacological and psychological interventions to prevent relapse in opiate addicts.