3xTg-AD	Triple-transgenic Alzheimer’s disease mouse model
5XFAD	Five familial Alzheimer’s disease mutations mouse model
AAO	American Academy of Ophthalmology
AD	Alzheimer’s disease
Akt	Protein kinase B
ALS	amyotrophic lateral sclerosis
AMPK	AMP-activated protein kinase
APP/PS1	Amyloid precursor protein/presenilin 1
BBB	blood–brain barrier
BDNF	brain-derived neurotrophic factor
cAMP	Cyclic adenosine monophosphat
CDR-SB	Clinical Dementia Rating–Sum of Boxes
CI	confidence interval
CNS	central nervous system
COVID-19	Coronavirus disease 2019
CREB	cAMP response element-binding protein
FGF21	fibroblast growth factor 21
GABA	Gamma-aminobutyric acid
Gαs	Stimulatory G protein alpha subunit
GCGR	glucagon receptor
GIP	glucose-dependent insulinotropic polypeptide
GIPR	glucose-dependent insulinotropic polypeptide receptor
GLIM	Global Leadership Initiative on Malnutrition
GLP-1	glucagon-like peptide-1
GLP-1R	glucagon-like peptide-1 receptor
GLP-1RA	glucagon-like peptide-1 receptor agonist
GSK-3β	glycogen synthase kinase-3 beta
HD	Huntington’s disease
HR	Hazard ratio
IGF-1	insulin-like growth factor 1
IL-1β	interleukin-1 beta
LPS	lipopolysaccharide
MAPK/ERK	mitogen-activated protein kinase/extracellular signal-regulated kinase
MCI	mild cognitive impairment
MDS-UPDRS	Movement Disorder Society–Unified Parkinson’s Disease Rating Scale
MRI	magnetic resonance imaging
MS	multiple sclerosis
MSA	multiple system atrophy
NAION	Non-arteritic anterior ischemic optic neuropath
NANOS	North American Neuro-Ophthalmology Society
NF-κB	nuclear factor kappa B
NLRP3	NLR family pyrin domain containing 3
OR	Odds ratio
PD	Parkinson’s disease
PI3K	phosphoinositide 3-kinase
PKA	protein kinase A
PPG	preproglucagon
RCT	randomized controlled trial
RR	Risk ratio
SIRT1	sirtuin 1
T2DM	type 2 diabetes mellitus
Th1/Th17	T helper type 1/type 17 cells
TNF-α	tumor necrosis factor alpha
UMSARS	Unified Multiple System Atrophy Rating Scale