Table 1.

Summary of phylogenetic differences in gut microbiome in Alzheimer’s Disease patients

Phylum	Class	Order	Family	Genus	reference
↓ Firmicutes	Clostridia	Eubacteriales	↓Lachnospiraceae in AD	↓Lachnospira in AD and MCI ↑ Blautia and Dorea in AD ↓Lachnoclostridium in AD ↓ Butyrivibrio (Butyrivibrio hungatei and Butyrivibrio proteoclasticus) in AD	(Guo et al., 2021; Haran et al., 2019; Li et al., 2019;Vogt et al., 2017 ; Zhuang et al., 2018)
			Eubacteriaceae	Species ↓ E. Rectale peripheral inflammatory state and amyloidosis E. eligens ↑in MCI then ↓in AD ↓E. eligens, E. hallii, and E. rectale in AD	(Cattaneo et al., 2017; Guo et al., 2021; Haran et al., 2019)
			Oscillospiraceae	↑Ruminococcus in AD ↑Subdoligranulum in AD ↓Ruminoclostridium 9 in AD and MCI	(Guo et al., 2021; Zhuang et al., 2018)
			↓Peptostreptococcaceae in AD		(Vogt et al., 2017)
			↓Clostridiaceae in AD	↓ SMB53 and Clostridium in AD ↓ Clostridium sp. in AD	(Haran et al., 2019; Vogt et al., 2017)
	↑Bacilli in AD	Lactobacillales	Streptococcaceae	↑Streptococcus in AD	(B. Li et al., 2019; Zhuang et al., 2018)
			↑Lactobacillaceae	↑Lactobacillus in AD but ↓ in amyloid burden	( Li et al., 2019)
	Erysipelotrichia	Erysipelotrichales	↓Turicibacteraceae in AD	↓Turicibacter in AD	(Vogt et al., 2017)
			Erysipelotrichaceae	↓ cc115 in AD	(Vogt et al., 2017)
	↓Negativicutes in AD	Veillonellales	Veillonellaceae	↓ Dialister In AD	(Vogt et al., 2017; Zhuang et al., 2018)
		Acidaminococcales	Acidaminococcaceae	↑Phascolarctobacterium in AD	(Vogt et al., 2017)
↑↓ Bacteroidetes	↓Bacteroidia in AD	Bacteroidales	↓↑Bacteroidaceae in AD	Bacteroides   ↓ (5 Studies: 2 AD, 1 AD and MCI, and 1 Dementia) ↑ (3 Studies:1 MCI and 2 AD) ↑B. Fragilis in AD	(Cattaneo et al., 2017; Guo et al., 2021; Haran et al., 2019; Li et al., 2019; Saji, Murotani, et al., 2019; Saji, Niida, et al., 2019; Vogt et al., 2017; Zhuang et al., 2018)
			Odoribacteraceae	↓Odoribacter spp. in AD	(Haran et al., 2019)
			Tannerellaceae	↓Parabacteroides in AD	( Li et al., 2019)
			↑Rikenellaceae in AD	Alistipes   ↓↑in AD	(Li et al., 2019; Vogt et al., 2017)
			Prevotellaceae	↓Paraprevotella in AD ↑Prevotella in AD	(Guo et al., 2021; Li et al., 2019)
↑ Proteobacteria	↑Gammaproteobacteria increases from HC to MCI to AD	↑Enterobacterales increases from HC to MCI to AD	↑Enterobacteriaceae increases from HC to MCI to AD	↑Escherichia/Shigella Peripheral inflammation and amyloidosis ↑Escherichia in AD ↑ Klebsiella spp. in AD	(Cattaneo et al., 2017; Haran et al., 2019; Li et al., 2019; Liu et al., 2019)
	Betaproteobacteria	Burkholderiales	Sutterellaceae	↓ Sutterella in AD	(Li et al., 2019)
	Deltaproteobacteria	Desulfovibrionales	Deltaproteobacteria	↑ Bilophila in AD	(Vogt et al., 2017)
↑↓ Actinobacteria	↑ Actinobacteria in AD	Bifidobacteriales	↓Bifidobacteriaceae	↓↑Bifidobacterium in AD	(Li et al., 2019; Vogt et al., 2017)
	Coriobacteriia	Eggerthellales	Eggerthellaceae	↓Adlercreutzia in AD ↑E. lenta in AD	(Haran et al., 2019; Vogt et al., 2017)

Bold text and shaded cell indicate reported alteration in taxa.

Abbreviations; ↓: decrease; ↑: increase; AD: Alzheimer’s Disease; HC: healthy control; MCI: Mild Cognitive Impairment.