Yeah I mainly agree with you, but I think there is a small chance that it could still indirectly effect some physical phenotypes and maybe (to a lesser extent) biochemical markers. Perhaps not a significant amount but possibly an amount of some degree. EG the endorphins produced as a result of thinking you have the real drug influences the amount of NGF being secreted OR the NGF translating into nervous system pulses are dampened by the hypothalamus. This could possibly lead to a slight reduction of the inflammatory response thus allowing the body to attempt to repair the associated BML to a slightly quicker extent compared to a patient that doesn't take any drug/remedial medication/activity?
Sure we are getting fairly granular and quite speculative on my part, I'm just saying it might translate to a tiny fraction in some cases and you cant necessarily rule it out altogether? Some people have a genetic disposition to an increase in natural dopamine for example.
Ok need more than my speculation/thoughts, what about this peer review that took a number of trials and found there was a link between physical phenotypes (but not so much of a link in Biomarkers as you commented).
I found one of their charts very interesting:
An RA trial was mentioned and also had a positive effect size (see above)
An extract in terms of their results and conclusion:
Results
The explorative analysis of outcome parameters and strength of placebo effects yielded a classification into responsive "physical" versus non-responsive "biochemical" parameters. In total, 50% of trials measuring physical parameters showed significant placebo effects, compared with 6% of trials measuring biochemical parameters. A subgroup meta-analysis substantiated the differential response (physical parameters: n = 14, Hedges' pooled effect size g = 0.34, 95% CI 0.22 to 0.46; biochemical parameters: n = 15, g = 0.03, 95% CI -0.04 to 0.10). The subanalysis of the second dataset supported the classification and revealed a significant improvement for physical parameters (n = 20, g = 0.22, 95% CI 0.07 to 0.36) and a deterioration for biochemical parameters (n = 6, g = -0.17, 95% CI -0.31 to -0.02).
Conclusion
The results suggest that placebo interventions can improve physical disease processes of peripheral organs more easily and effectively than biochemical processes. This differential response offers a good starting point for theoretical considerations on possible mediating mechanisms, and for future investigations in this field.REFERENCE for the Peer Reviewed Paper:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1847831/
(20min delay)