People with preclinical Alzheimer’s disease have notably different gut microbiome features from those without the condition. The distinct gut microbiome features may help physicians detect preclinical Alzheimer’s early for individuals at risk. People with the preclinical condition have normal cognitive ability, while already show the biological evidence of Alzheimer’s in the brain, blood, or the fluid surrounding the brain and spinal cord. 

Microbiome contains microbes, including bacterium, fungus, parasite, and virus, that live throughout our body. A well-balanced microbiome system is beneficial to our health. Particularly, microbiome in the gut is associated with other important systems in our body, such as the digestive, immune, and nervous system. 

In a recent study, researchers explored whether the gut microbiome features in people with preclinical Alzheimer’s differ from that in healthy individuals. They also assessed whether the different gut microbiome features can improve early detection of preclinical Alzheimer’s. 

In order to answer these questions, the researchers included 115 healthy participants and 49 with preclinical Alzheimer’s from the Knight Alzheimer’s Disease Research Center at Washington University. They evaluated stool samples collected from 2019 to 2021 from the participants aged between 68 and 94 years. 

The nutrition status of the two groups were similar, in terms of their calorie sources and intake, amounts of specific vitamins, minerals, or other main nutrients, such as carbohydrate, fat, and fiber. While, the researchers found that the individuals with preclinical Alzheimer’s showed notably different gut microbiome features, compared with the healthy individuals. The microbes associated the most with preclinical Alzheimer’s are Dorea formicigenerans, Oscillibacter sp. 57_20, Faecalibacterium prausnitzii, Coprococcus catus, and Anaerostipes hadrus, which are all bacteria.

Furthermore, the researchers included the participants’ gut microbiome data to a predictive model of preclinical Alzheimer’s. The prediction was more accurate and specific, when they used the gut microbiome data in this model together with data of demographics, clinical conditions and genetic status. The prediction was also more accurate and sensitive when they combined the gut microbiome data with demographics and clinical conditions data.

The different gut microbiome features could improve the early detection process of preclinical Alzheimer’s before individuals receive necessary follow-up procedures, such as brain scans, to verify the condition. People provide their stool samples for testing the gut microbiome features, they can easily collect the samples at home. This makes testing gut microbiome features an easy-to-access, inexpensive, and less invasive method of detecting preclinical Alzheimer’s.

Preclinical Alzheimer’s does not mean that a person will definitely progress to Alzheimer’s. In future studies, scientists need to explore the relations between changes in gut microbiome and progression of Alzheimer’s. The results will tell us more about whether changes in gut microbiome over time can predict Alzheimer’s progression, or a stop to this progression. 

This study was published in Science Translational Medicine. Image credit: Canva

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