Table 1. Search strategy for PubMed .

Order	Terms
#1	“Hyperbaric Oxygenation”[MeSH Terms]
#2	“hyperbaric oxygenations”[Title/Abstract]OR “hyperbaric oxygen therapy”[Title/Abstract]OR “hyperbaric oxygen therapies”[Title/Abstract]OR“high pressure oxygen”[Title/Abstract]OR “oxygen therapy”[Title/Abstract]
#3	#1 OR #2
#4	“Parkinson Disease”[MeSH Terms]
#5	“Parkinson’s Disease”[Title/Abstract]OR “Idiopathic Parkinson’s Disease”[Title/Abstract]OR “Idiopathic Parkinson Disease”[Title/Abstract]OR “Lewy Body Parkinson’s Disease”[Title/Abstract]OR “Lewy Body Parkinson Disease”[Title/Abstract]OR “Primary Parkinsonism”[Title/Abstract]OR “Paralysis Agitans”[Title/Abstract]
#6	#4 OR #5
#7	“Cognitive Dysfunction”[MeSH Terms]
#8	“Dementia”[MeSH Terms]
#9	“Cognitive Dysfunctions”[Title/Abstract]OR “Cognitive Impairments”[Title/Abstract]OR “Cognitive Impairment”[Title/Abstract]OR “Mild Cognitive Impairment”[Title/Abstract]OR “Mild Cognitive Impairments”[Title/Abstract]OR “Cognitive Disorder”[Title/Abstract]OR “Cognitive Disorders”[Title/Abstract]OR “Cognitive Decline”[Title/Abstract]OR “Cognitive Declines”[Title/Abstract]OR “Dementias”[Title/Abstract]OR “Amentia”[Title/Abstract]OR “Amentias”[Title/Abstract]
#10	#7 OR #8 OR #9
#11	“randomized controlled trial” [Publication Type]
#12	“controlled clinical trial” [Publication Type]
#13	“randomized”[Title/Abstract]OR “placebo”[Title/Abstract]OR “clinical trials as topic”[Title/Abstract]
#14	#11 OR #12 OR #13
#15	#3 AND #6 AND #10 AND #14