Reference request: one in six adults have a PPD

Hello all!

Great to be a member of this community.

Does anyone know where the statistic that one in six adults has a Psychophysiologic Disorder comes from?

It is quoted on the PPD Association website and in the description for the 'Psychophysiologic Disorders' book (https://www.amazon.co.uk/Psychophys...rofessional-Diagnosis-Treatment/dp/1696486866), but I can't find the actual reference. The closest I can find is 25-33% of primary care patients have medically unexplained symptoms (Clarke, DD (2016)).

Big thanks!

Flick