Thanks Debi, I was asking that question precisely for the reasons you stated. If Dopamine is what might be involved in Placebo effect, how can one do a controlled clinical trial for PD? Are longitudinal studies better for PD? Each patient serves as his or her own control for whatever parameters tested in the clinical trial. I am not too familiar with clinical studies design and just thinking aloud. Any thoughts on alternative controls to replace placebos in clinical trials?

Girija

QUOTE=Debi Brooks;467738]Again, not an expert but I've heard this discussed frequently in scientific meetings and two bits that come up regularly that might be of interest...

placebo is a biological effect and is found in all sorts of diseases/interventions...it does seem to be particularly vexing in PD...why? the placebo is believed to occur in some part due to triggers in the reward system in the brain--guess which chemical? dopamine. So, in a clinical intervention that actually targets the dopamine system directly or even peripherally, such as many treatment strategies in PD, you have the extra confounding effect. I think there is data that suggests placebo effect can linger particularly long in PD too (many years after intervention).

Debi[/QUOTE]