BBB	Blood–Brain Barrier
BDNF	Brain-Derived Neurotrophic Factor
CBD	Cannabidiol
Cho	Choline
COMT	Catechol-O-Methyltransferase
Cr	Creatine
CSF	Cerebrospinal fluid
DOPAC	Dihydroxyphenylacetic Acid
GABA	Gamma-Amminobutyric Acid
GLP-1	Glucagon-like Peptide-1
Glu	Glutamate
Glx	Glutamate + Glutamine
1H-MRS	Proton Magnetic Resonance Spectroscopy
H&Y	Hoehn and Yahr
HC(s)	Health Control(s)
IPD	Idiopathic Parkinson’s disease
ITT	Intention-to-treat
MAO-B	Monoamine Oxidase B
MR	Magnetic Resonance
MRI	Magnetic Resonance Imaging
MRS	Magnetic Resonance Spectroscopic
MRSI	Magnetic Resonance Spectroscopic Imaging
NA	Not applicable
NAA	N-acetylaspartate
NIH	National Institutes of Health
NMDA	N-methyl-D-aspartate
NR	Not Reported
PD	Parkinson’s Disease
PDQ-39	The Parkinson’s Disease Questionnaire
PET	Positron emission tomography imaging
PICO	Population, Intervention, Comparison, Outcome
PRISMA	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
ROS	Reactive oxygen species
SN	Substantia Nigra
T	Tesla
tCr	total Creatine
tNAA	total N-acetylaspartate
UPDRS	Unified Parkinson’s Disease Rating Scale
VOI	Volume of interest