Both drug addiction and food intake disorders constitute increasingly serious health care and social problems in the EU and are also respon-sible of the loss of million of working hours every year.

In the European Union compulsive consumption behaviours, such as drug addiction and overeating, constitute a major social, economical and psychological health problem. For example, around 10 % of the total population was found to have drug-related (including licit and illicit drugs) disorders, with a cost (morbidity and mortality) for the second half of the 1990s of about 16 billion euros.

Moreover, Europe has the highest consumption of alcohol in the world, and consequently the highest rate of harm related to alcohol (Rehn, Room and Edwards, WHO, Regional Office for Europe, 2001). The deleterious effects of alcohol addiction are well researched and documented, and relate not only to annual consumption but also to drinking pattern. Deleterious effects on physical health lead to excess morbidity and premature death. In addition, physical harm from accidents and violence are serious consequences of excessive drinking as well as illicit drug use. Psychological harm in the form of anxiety, depression and suicides are not uncommon. Offspring and other family members are negatively affected. Social effects result from accidents, crimes and violence related to alcohol and drug consumption, including lost productivity due to sick days and unemployment. The total cost to society of only excessive alcohol consumption is estimated to amount to up to 3 % of gross domestic product.

Overeating leading to overweight or obesity is a disorder that also has major consequences in the EU population. Excess bodyweight is the sixth most important risk factor contributing to the overall burden of disease worldwide; 1.1 billion adults and 10 % of children are now classified as overweight or obese. The number of deaths per year attributable to obesity may reach 30 000 in some European countries (National Audit Office, 2001) and obesity has more recently been shown to decrease life expectancy by 7 years at the age of 40 years. Despite the enormous human and financial costs of drug addiction and eating disorders efficient treatments of these pathological behaviours are currently lacking. An essential step for developing appropriate treatments of such compulsive behaviours is the identification of those factors that underlie the higher vulnerability of certain individuals to shift from "non-pathological" drug use or food consumption to the "compulsive drug/food use" that characterize drug dependence or chronic overeating. Indeed, although a large number of subjects sample addictive drugs, only some of them develop a true addiction.