[Hypothesis: Parkinson's disease, reward deficiency syndrome and addictive effects of levodopa]

Since Parkinson's disease (PD) patients could suffer from a reward deficiency syndrome, they are particularly prone to develop addictive behaviours. Dopamine is involved in reward processing and in addiction. Pulsatile administration of antiparkinsonian drugs may lead to the development of dyskinesias and addictive behaviours. However, this phenomenon occurs in very few cases. Indeed, both processes share molecular mechanisms although with some differences such as the topography of the changes (it predominates in motor regions in PD with dyskinesias and in limbic regions in addictions). Nevertheless, investigations conducted to know the physiopathology of levodopa-induced dyskinesias may lead to important cues for understanding the underlying mechanisms responsible for addiction. Thus, this may have important implications for the discovery of new therapeutic strategies.