Following this puts new work involving it at the top of your briefing, with a note saying why it is there. Links are taken from the source record, never inferred.
This is a narrative review summarizing preclinical mechanistic evidence from 33 natural compounds; it raises therapeutic questions rather than testing them in humans or providing clinical evidence of efficacy.
This is a protocol for a planned systematic review and network meta-analysis, not a completed study with empirical results; it describes the design and methods that will be used to evaluate PEI and CBT but reports no data or findings.