Could drugs designed to suppress appetite also treat addiction?

Scientists at Imperial College London are planning to investigate whether appetite-regulating hormones produced by the gut could reduce the urge to smoke and drink.

Groups of ex-smokers, recovering alcoholics and healthy volunteers will undergo tests inside an MRI scanner to see if gut hormones reduce how their brains respond to pictures of cigarettes, alcoholic drinks and food, and alter other addictive behaviours that predispose to relapse, such as their response to stress.

Previous studies in animals have shown that targeting hormones that make us feel full after eating not only reduces appetite and craving for food, but also alcohol, nicotine and other drugs of abuse.

It is thought that the effect comes about by interfering with the 'reward' mechanism in the brain that makes us derive pleasure from these behaviours. They may also alter behaviours such as impulsivity (wanting rewards now rather than being prepared to wait), and the response to stress (for example overeating when upset or depressed).

The four-year 'Gut Hormone in Addiction' (GHADD) study, funded as part of a £60-million investment from the Medical Research Council's (MRC) Experimental Medicine Challenge grant scheme, will be led by Dr Tony Goldstone, Consultant Endocrinologist, and David Nutt, the Edmond J Safra Professor of Neuropsychopharmacology, from the Department of Medicine at Imperial College London.

''Smoking and alcohol dependence are major causes of ill health with huge social and economic impacts,'' says Dr Goldstone. ''Drugs that help people to stop in the long term are limited, and many people relapse after giving up for a period of time.

''Evidence from animal studies suggests that several hormones that regulate appetite, and the desire and craving for food, also modulate the desire for drugs of abuse, including nicotine and alcohol. We want to see if that translates to potential benefits in humans.

''This proof-of-concept experimental medicine study will use functional brain imaging and behavioural tests to investigate the effect of gut hormones on addictive and eating behaviours in humans. It is a unique collaborative project between endocrinologists, addiction psychiatrists and neuroimaging scientists. Our ultimate aim is to find new treatments that help prevent addicts from relapsing, which would have a massive impact on the health of individuals and society. Drugs that mimic these hormones are already licensed for the treatment of diabetes or are under development.''

The volunteers will undergo functional magnetic resonance imaging (fMRI) scans at the Imanova Centre for Imaging Sciences, based at Imperial's Hammersmith Campus.

Professor Nutt says, "Gut hormones and addiction are two of the great research strengths of Imperial's Faculty of Medicine, and this project will bring those together. One of the main reasons I came here was to work with Imperial's world-leading endocrine researchers, and I'm delighted to now have the opportunity to do this."