This study investigates the gut microbiome alterations in Alzheimer's disease (AD) and their potential role in AD pathology. The researchers characterized the bacterial composition of fecal samples from AD patients and age- and sex-matched controls using 16S rRNA gene sequencing. They found that AD participants had a reduced microbial diversity and a distinct microbial community composition compared to controls. Specifically, AD participants showed decreased Firmicutes, increased Bacteroidetes, and decreased *Bifidobacterium*. Additionally, the abundance of differentially abundant genera was correlated with cerebrospinal fluid (CSF) biomarkers of AD pathology, such as Aβ42/Aβ40 ratio, phosphorylated tau (p-tau), and YKL-40 levels. These findings suggest that gut microbial alterations may contribute to AD and could be a target for therapeutic intervention. The study also highlights the importance of the gut-brain axis in the development and progression of AD.This study investigates the gut microbiome alterations in Alzheimer's disease (AD) and their potential role in AD pathology. The researchers characterized the bacterial composition of fecal samples from AD patients and age- and sex-matched controls using 16S rRNA gene sequencing. They found that AD participants had a reduced microbial diversity and a distinct microbial community composition compared to controls. Specifically, AD participants showed decreased Firmicutes, increased Bacteroidetes, and decreased *Bifidobacterium*. Additionally, the abundance of differentially abundant genera was correlated with cerebrospinal fluid (CSF) biomarkers of AD pathology, such as Aβ42/Aβ40 ratio, phosphorylated tau (p-tau), and YKL-40 levels. These findings suggest that gut microbial alterations may contribute to AD and could be a target for therapeutic intervention. The study also highlights the importance of the gut-brain axis in the development and progression of AD.