Placebo and dopamine - true or false?

The placebo response seem to be able to account for a considerable amount of the effects of both medical and behavioral treatments.

While placebo are often used in order to test the actual efficacy of a given treatment, there is mounting evidence that this approach suffers from lack of understanding of placebo as a phenomena.

This is needed both in order to design adequate trials, but also to enable manipulation of the placebo-response in order to optimize treatment outcomes.Although placebo has been hypothesised to be closely linked to dopaminergic signalling, studies confirming this hypothesis have been scarce and there are reports of both a dopamin-dependent and independent pathway for installing placebo.

DLPFC has been suggested as a potential area involved in the placebo response, but there is a gap in knowledge regarding studies assessing both reactivity in DLPFC and release of dopamine.

There are also indications of a sex difference in responsivity to the potential dopaminergic aspect of placebo.This study thus uses a pain-inducing paradigm to, within healthy controls and while taking sex hormones into account, assess the relation between endogenous dopaminergic signalling, brain activity and placebo response with PET-fMRI.

To further elucidate the interaction between dopamine and activity in the DLPFC the study also, during instalment of a placebo response, use a four-armed trial applying inhibitory TMS over DLPFC and/or exogenous administration of dopamine (Levodopa)