123(I)-FP-CIT SPECT	iodine I 123–radiolabeled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane single-photon emission computed tomography
AD	Alzheimer’s disease
aPD	anxious but not depressive
ApoA1	apolipoprotein A1
coPD	comorbid depressive and anxious
CRP	C-reactive protein
CSF	cerebrospinal fluid
DaT	dopamine transporter
dPD	depressive but not anxious
DTI	diffusion tensor imaging
EPPD	early progressive PD
fMRI	functional magnetic resonance imaging
fNIRS	functional near-infrared spectroscopy
FOG	freezing of gait
GCO	global composite outcome
GMV	gray matter volume
H&Y	progression between V0 and V04
HC	healthy control
HVLT-R	Hopkins verbal learning test—revised
IBIL	indirect bilirubin
IGF1	insulin-like growth factor 1
IMU	inertial measurement unit
LSTM	long short-term memory
MCI	mild cognitive impairment
MD	mean diffusivity
MIPD	minimally improving PD
MMSE	Mini Mental State Examination
MRI	magnetic resonance imaging
NC	normal controls
nPD	without depressive or anxious symptoms
NPPD	non-progressive PD—no H&Y progression
PD	Parkinson’s disease
PD-aMCI	Parkinson’s disease—amnestic MCI
PD-naMCI	Parkinson’s disease—non-amnestic MCI
PET	positron emission tomography
PFC	prefrontal cortex
PIGD	postural instability and gait difficulty
QOL	quality of life
RBD	rapid eye movement sleep behavior disorder
ReHo	regional homogeneity
RFOG	responsive freezing of gait
ROM	range of motion
SBR	striatal binding ratio
SFT	serum insulin-like growth factor-1
SPECT	single-photon emission computed tomography
SPPD	secondarily progressive PD
TD	tremor-dominant
UPDRS	unified Parkinson’s disease rating scale
URFOG	unresponsive freezing of gait