Unraveling the Connection Between Alzheimer’s And Cancer

Alzheimer’s and Reduced Cancer Risk: Unveiling a Mysterious Link

Research has revealed that individuals with Alzheimer’s disease appear to have a lower risk of developing certain cancers, and a recent study involving rodents may provide insight into this phenomenon.

In a study conducted in China, scientists observed that mice exhibiting Alzheimer-like symptoms had a notably reduced occurrence of colorectal cancer. However, after receiving a stool transplant from a healthy mouse, the cancer rates in these mice normalized.

Gut Bacteria and Alzheimer’s: A Significant Relationship

These findings imply a significant relationship between Alzheimer’s symptoms and the composition of gut bacteria. Current evidence suggests that specific gut microbes can influence the immune system, thereby affecting brain health.

Previous rodent studies have also established connections between the gut microbiome and Alzheimer’s symptoms. Remarkably, recent experiments have shown that stool transplants can transfer memory impairment from one rodent to another.

This new research delves deeper into the intricate relationship linking Alzheimer’s, the gut microbiome, and cancer. Retrospective studies have indicated that human patients with Alzheimer’s face about half the cancer risk compared to those without the disease, while individuals with cancer are 35% less likely to develop Alzheimer’s. The reason behind these correlations remains unclear, although colorectal cancer displays the most significant links with Alzheimer’s.

Researchers at the First Hospital of Hebei Medical University in China conducted experiments demonstrating that mice with Alzheimer-like symptoms showed resistance to artificially induced colon cancer. The researchers reduced intestinal inflammation in the mice, but this suppression was reversed after the mice received a fecal transplant from a healthy, younger mouse.

To identify the specific gut microbes involved, researchers examined the microbiota of their mouse models and identified several candidates, including a gram-negative bacterium called Prevotella. Treating these mice with Prevotella caused their guts to produce fewer pro-inflammatory immune cells, even when exposed to harmful pathogens.

The “Leaky Gut” Hypothesis and Its Impact on Health

This decreased inflammatory response may have been partly due to a “leakier” gut, which allowed certain microbial byproducts to enter the bloodstream more easily. Previous studies have established that lipopolysaccharides (LPS) derived from the Prevotella genus play a role in mucosal barrier inflammatory responses. For example, Prevotella bivia is known to produce high levels of LPS, which could create a toxic environment harmful to dopamine neurons crucial for cognitive and motor functions.

Parkinson’s, Inflammation, and Gut Microbiota

Recent human clinical trials have shown that stool transplants can improve motor symptoms in Parkinson’s disease, a condition closely tied to the degeneration of dopamine neurons. Since inflammation plays a major role in tumor formation, researchers suggest that the anticancer effects seen in Alzheimer’s mouse models could be related to the gut’s inflammatory tolerance driven by specific bacterial genera.

While epidemiological data has previously suggested a correlation between cancer and Alzheimer’s, this new research provides concrete biological and experimental evidence supporting an inverse relationship between the two conditions, particularly regarding the incidence of Alzheimer’s disease and colorectal cancer.

Read the original Article: Science Alert

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