We think it’s a brain disease. Instead, research increasingly shows us that Alzheimer’s is a pathology that can affect other organs through the brain. This is demonstrated once again by a study conducted by John Mamo and colleagues from Curtin University in Bentley, Australia, just published on Plos Biology. According to which the brain’s neurodegeneration could also be caused by the amyloid protein produced in the liver, an organ that could therefore play a key role in the onset or progression of the disease.
The experiment
Researchers have long known that the so-called “plaques” of beta-amyloid are visible in the brains of people with Alzheimer’s, or messy tangles of this protein that surround and destroy synapses, preventing neurons from functioning properly and exchanging information, causing problems. cognitive problems such as memory loss. But amyloid isn’t just produced by the brain. In fact, we have long known that other organs produce this protein, such as the spleen, or elements such as platelets.
The hypothesis explored by Australian researchers is that amyloid produced by the liver also contributes to the onset of the disease. The point is that it is not easy, looking at the plaques in the brain, to distinguish the different sources of production. To overcome this obstacle, the study authors developed a mouse that produces human amyloid only in liver cells, and noted how the protein was transported in the blood by lipoproteins (macromolecules made up of varying amounts of proteins and lipids) rich in triglycerides. just like in humans, eventually reaching the brain. After a period of time, the mice treated in this way developed neurodegeneration and brain atrophy, accompanied by neurovascular inflammation and dysfunction of the brain capillaries, conditions that also generally occur in human patients with Alzheimer’s. Not only that: by subjecting them to learning and memory tests, the animals obtained results significantly lower than those of the control group.
The hypothesis
According to the researchers, therefore, the results of this study show that amyloid produced outside the brain has the ability to cause neurodegeneration. A discovery that could also have some repercussions on pharmacological research – for example with drugs targeted against amyloid-carrying lipoproteins – and even on the nutrition of patients. That there is some link between the liver and Alzheimer’s disease is well known, he comments Alessandro Padovani, national secretary of the Italian Society of Neurology and director of the Neurological Clinic of the University of Brescia. “In the literature it is shown that in people with Alzheimer’s there is an increased level of liver enzymes and greater liver pain,” explains the neurologist. This could represent a factor of further fragility in a body that already has to bear greater fragility due to amyloid. But we also know that the amyloid produced by the brain must be degraded by the liver, which over time can lose its efficiency in detoxification, generating accumulations which in turn, in a vicious circle, make the degradation less and less efficient.
Or finally, as the Australian study shows, we can hypothesize that the liver itself is an amyloid producer. “Personally I believe that patients with Alzheimer’s are in general very sensitive to the functioning of the body, that liver alterations can cause systemic inflammation, and that the link between liver function, intestinal function and microbiome also plays a role. In short – continues Padovani – I don’t think that the liver has a direct effect in the development of Alzheimer’s, but I think there is a synergy of mechanisms that lead people to be less resilient to amyloid accumulation. If I improve, or at least not worsen, liver function guarantees also better resistance to the toxic effect of amyloid “.
Not just a brain disease
Seen in this perspective, Alzheimer’s ceases to be just a brain disease, to become a complex disease that involves multiple organs. “The liver is essential to detoxify and maintain an adequate metabolism. If it functions poorly, even more delicate organs such as the brain are affected. This is why, in general, in the treatment of Alzheimer’s we must not underestimate even the slightest pathologies affecting other organs. , and heal the body to ensure patients greater resilience to amyloid accumulations “.
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