Researchers identify three intestinal bacteria found in dementia with
Lewy bodies

Date:
February 28, 2023
Source:
Nagoya University
Summary:
Researchers have identified gut bacteria that are associated with
dementia with Lewy bodies. Changing the levels of three bacteria,
Collinsella, Ruminococcus, and Bifidobacterium, may delay the
onset and progression of this neurodegenerative disease.


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FULL STORY ========================================================================== Dementia with Lewy bodies (DLB), one of the most common forms of
dementia, has no cure. Previous studies suggested that gut bacteria,
the microorganisms that live in the human digestive tract, play a role
in Parkinson's disease, another neurodegenerative disorder, but the
bacteria involved in DLB had not been identified. Now, a group led
by researchers at the Nagoya University Graduate School of Medicine
in Japan has identified three bacteria involved in DLB: Collinsella, Ruminococcus,and Bifidobacterium. Their findings, reported in npj
Parkinson's Disease, suggest new avenues for diagnosis and treatment.


==========================================================================
The onset of DLB is associated with abnormal deposits of alpha-synuclein,
a protein in the brain that plays a role in the transmission of signals
between neurons. The presence of these deposits, known as 'Lewy bodies', affects chemicals in the brain, leading to declines in thinking, reasoning
and memory.

Symptoms include confusion, memory loss, impaired movement, and visual hallucinations.

Parkinson's disease also starts with movement problems, but some patients develop cognitive decline within one year. These patients are diagnosed
with DLB when this cognitive decline occurs. Physicians find it difficult
to predict which people with Parkinson's disease will develop cognitive
decline within a year and become patients with DLB.

A research group led by Associate Professor Masaaki Hirayama (Omics
Medicine), Professor Kinji Ohno (Neurogenetics), and Assistant Professor Hiroshi Nishiwaki (Neurogenetics) of Nagoya University Graduate School
of Medicine, in collaboration with Okayama Neurology Clinic, Iwate
Medical University, and Fukuoka University, analyzed microorganisms in
the gut and fecal bile acids of patients with DLB, Parkinson's disease,
and rapid eye movement behavior disorder. They discovered that three
intestinal bacteria, Collinsella, Ruminococcus,and Bifidobacterium,
were associated with patients with DLB. This may suggest possible ways
of diagnosing and treating this neurodegenerative disease.

The researchers also found similarities between the gut bacteria
involved in Parkinson's disease and DLB. In both diseases, the bacteria Akkermansia, which degrades the intestinal mucosa, increased. On the
other hand, the bacteria that produce short-chain fatty acids (SCFA)
in the gut decreased. "Decreases in SCFA-producing bacteria have been repeatedly reported in Parkinson's disease, Alzheimer's disease, and
ALS," explains Ohno. "This suggests that it is a common feature of neurodegenerative diseases." SCFA are important because they produce
regulatory T cells. These types of cells play a critical role in
regulating the immune system by suppressing neuroinflammation.

On the other hand, in patients with DLB, the researchers found an increase
in Ruminococcus torques, an increase in Collinsella, and a decrease in Bifidobacterium. This was different from Parkinson's disease patients,
whose levels did not change. In the future using these insights, doctors
may be able to analyze the bacteria in a person's digestive tract to distinguish DLB from Parkinson's disease.

Importantly, the reduced levels of Bifidobacteriummayalsosuggest
possible ways to treat DLB. Bifidobacterium increases brain-derived neurotrophic factor, a key protein that supports the growth, development
and maintenance of neurons in the central and peripheral nervous
systems. Therefore, its decrease in DLB is likely to be associated with cognitive decline.

Similarly, both Ruminococcus torquesand Collinsellaare intestinal bacteria
that carry an enzyme, the product of which regulates inflammation
in a region of the brain called the substantia nigra.The substantia
nigra produces dopamine, a neurotransmitter that is involved in the
regulation of movement and is deficient in Parkinson's disease. Compared
to Parkinson's disease, the levels of these bacteria were higher in
people with DLB. This may explain why the effect on movement is delayed,
a key feature that distinguishes DLB from Parkinson's disease.

"Our findings can be used both for both diagnosis and treatment," explains Ohno. "If a patient with Parkinson's disease develops dementia in one year after the onset of motor symptoms, they are diagnosed with DLB. However,
we cannot currently predict whether a patient with Parkinson's
disease will become a DLB patient. The gut microbiome will help to
identify such patients." "In terms of treatment, the administration
of Ruminococcus torques and Collinsellain patients with Parkinson's
is expected to delay neuroinflammation in the substantia nigra," Ohno
added. "Therapeutic intervention to increase Bifidobacteriummay delay
the onset and progression of DLB and reduce cognitive dysfunction."
"The presence of intestinal bacteria unique to DLB may explain why some patients develop Parkinson's disease and others develop DLB first,"
Ohno said.

"Normalizing the abnormal bacteria shared between DLB and Parkinson's
disease may delay the development of both diseases. Improving the
gut microbiota is a stepping stone in the treatment of dementia. Our
findings may pave the way for the discovery of new and completely
different therapeutics."
* RELATED_TOPICS
o Health_&_Medicine
# Parkinson's_Research # Diseases_and_Conditions #
Alzheimer's_Research
o Mind_&_Brain
# Parkinson's # Disorders_and_Syndromes # Caregiving
o Plants_&_Animals
# Bacteria # Veterinary_Medicine # Extreme_Survival
* RELATED_TERMS
o Dementia_with_Lewy_bodies o Alzheimer's_disease o
Bacteria o Delayed_puberty o Multi-infarct_dementia
o Rocky_Mountain_spotted_fever o Body_odor o
Bovine_spongiform_encephalopathy

========================================================================== Story Source: Materials provided by Nagoya_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Hiroshi Nishiwaki, Jun Ueyama, Kenichi Kashihara, Mikako Ito,
Tomonari
Hamaguchi, Tetsuya Maeda, Yoshio Tsuboi, Masahisa Katsuno,
Masaaki Hirayama, Kinji Ohno. Gut microbiota in dementia
with Lewy bodies. npj Parkinson's Disease, 2022; 8 (1) DOI:
10.1038/s41531-022-00428-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230228205244.htm

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