a protein in the brain believed to be a key contributor to the development of alzheimer’s is also produced in the liver, according to new research that says the football-sized organ may play a larger role in the progression of the disease than previously thought.
alzheimer’s disease
is a degenerative condition that is believed to be the result, in part, of the accumulation of amyloid in the brain that leads to the slow death of neurons. this process eventually produces symptoms of memory loss, difficulty thinking or problem solving and changes in mood and behaviour.
the buildup of amyloid, also known as a-beta, in the brain is thought to be one of the key causes of the neurodegeneration that gives rise to alzheimer’s, the most common cause of dementia in the world. but the protein is also produced in peripheral organs, raising the possibility that a-beta created elsewhere in the body can travel to the brain and contribute to the disease. this hypothesis has been difficult to test, however, because the brain also produces the protein and distinguishing between the two sources has been difficult.
the current study,
published in the journal plos biology
, sought to rectify this by developing a mouse model that was only capable of producing a-beta in its liver cells.
the experiments revealed
that the protein was able to make its way to the brain by travelling through the blood on triglyceride-rich lipoproteins — the same path it takes in humans. once there, the mice began to experience brain atrophy and neurodegeneration, in addition to neurovascular inflammation and dysfunction of cerebral capillaries, all common hallmarks of alzheimer’s disease. these mice became unable to perform learning tests that depend upon the function of the brain’s hippocampus, a structure vital to the creation of new memories.
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