Aβ	β-amyloid
AD	Alzheimer’s disease
BBB	blood–brain barrier
CUS	chronic unpredictable stress
CRF	corticotrophin-releasing factor
EE	environmental enrichment
GI	gastrointestinal tract
GF	germ free
HS	hormonal stress
HPA	hypothalamic–pituitary–adrenal
IBS	irritable bowel syndrome
LPS	lipopolysaccharides
MCI	mild cognitive impairment
MS	maternal separation
NFT	neurofibrillary tangles
ptau	phosphorylated tau
PD	postnatal day
PE	physical enrichment
PS	psychosocial stress
RIS	restraint and immobility stress
SCFA	short-chain fatty acids
SS	sleep restriction stress
SE	social enrichment