For some time, scientists have been finding more and more evidence about the relationship between various neurological disorders and the microbiome that lives in various parts of our body.
In this line of research, a recent study carried out by the University of Nagoya (Japan) and published in the specialized media npj Parkinson’s Disease has identified abnormal levels in three bacteria in patients with dementia with Lewy bodies (DLB).
Parkinson’s and dementia with Lewy bodies
DLB is a neurodegenerative disease characterized by the appearance in brain tissue of abnormal deposits of alpha-synuclein, a protein normally involved in the transmission of signals between neurons. The presence of these deposits, known as Lewy bodies, it affects brain chemistry leading to declines in thinking, reasoning, and memory. Symptoms include confusion, memory loss, movement impairments, and visual hallucinations.
Parkinson’s disease, for its part, also begins with motor problems, but some patients develop cognitive decline within a year. These patients are diagnosed with DLB, but to date there is no way to predict which Parkinson’s patients will evolve to DLB.
Thus, the authors of the work analyzed the microorganisms in the intestine and the fecal bile acids of patients with DLB, Parkinson’s and REM behavior disorder. In this way, they discovered that the patients with DLB presented as a characteristic altered levels of three bacterial species (Collinsella, Ruminococcus y Bifidobacterium).
Differences in bacteria
Specifically, the levels of the first two bacteria were elevated in these patients, while the levels of the third were reduced. This may help explain some pathogenic features of the disease: so much Collinsella as Ruminococcus they carry an enzyme whose product regulates inflammation in a region of the brain called the substantia nigra (the area also produces dopamine, a neurotransmitter involved in the regulation of movement and deficient in Parkinson’s). On the contrary, Bifidobacterium increases levels of brain-derived neurotrophic factor, a key protein in the growth, development, and maintenance of neurons in the central and peripheral systems.
On the other hand, both DLB and Parkinson’s showed a common feature: an increase in the levels of Akkermansiawhich degrades the intestinal mucosa.
In the end, the researchers conclude by noting that these findings may have implications for both diagnosis and treatment; differences in the bacterial signature, for example, could hold the key to predict which patients with Parkinson’s will evolve towards the DLB.
References
Nishiwaki, H., Ueyama, J., Kashihara, K. et al. Gut microbiota in dementia with Lewy bodies. npj Parkinsons Disase (2022). DOI: https://doi.org/10.1038/s41531-022-00428-2