The composition of the gut microbiome in people in the early stages of Alzheimer’s disease, when brain changes occur but not cognitive symptoms, is significantly different from that of healthy people. So, microbiome analysis could be a way to identify people at higher risk of developing dementia, but also in the development of preventive strategies, through which the intestinal microbiome is modified to prevent cognitive decline. The data comes from a study conducted at Washington University.
The early stages of Alzheimer’s disease, when beta amyloid and tau protein build up in the brain, without obvious signs of neurodegeneration and cognitive decline, can last as long as two decades. By the time cognitive symptoms appear, there are already pathophysiological changes, many of which are irreversible.
In the new study, participants provided stool, blood and cerebrospinal fluid samples, kept food diaries and underwent PET and MRI brain scans. Of the 164 participants, 49 had signs of Alzheimer’s disease.
People with preclinical forms of Alzheimer’s have a different gut microbiome profile than healthy people, even though they have a similar diet. And these changes correlate with the levels of pathological brain proteins. Also, including microbiome data in predictive models for disease increased their sensitivity by 11% and a 27% increase in specificity.
The authors explained that it is not yet known exactly what the causal relationship is, whether the gut microbiome influences brain changes or vice versa. However, the microbiome profile correlates with changes in preclinical forms of Alzheimer’s disease, which could elucidate the etiology of the disease and facilitate the development of markers for early assessment of Alzheimer’s risk.
Next, a 5-year follow-up study will be launched to test whether changes in the gut microbiome are a cause or a consequence of the brain changes that occur in the early stages of Alzheimer’s disease.
The intestinal microbiome is composed of billions of species of bacteria, viruses, fungi and has been shown to play an important role in neuroinflammation which accompanies many neurological conditions, including multiple sclerosis and Parkinson’s disease. Alzheimer’s disease is a neurodegenerative disorder and is the leading cause of dementia. Currently, there are few disease-modifying therapies. Biological markers of the disease are representatives of beta amyloid plaques, tau protein and markers of neuroinflammation.
Environmental factors along with genetic factors contribute to the development of pro-inflammatory mechanisms at the level of the intestinal microbiome, changing its composition over time and the type of metabolites generated at this level. All these changes, as well as the hormones produced by the intestinal neuroendocrine systems, can alter the blood-brain barrier and the cells of the nervous system involved in the development of Alzheimer’s disease.
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2023-07-13 12:15:43
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