The standard explanation for what causes Alzheimer's is known as the amyloid hypothesis, which posits that the disease results from of an accumulation of the peptide amyloid beta, the toxic protein fragments that deposit in the brain and become the sticky plaques that have defined Alzheimer's for more than 100 years.
Billions of dollars are spent yearly targeting this toxic peptide but what if this is the wrong target? What if the disease begins much earlier, fueled by a natural process? Reporting in the current edition of the journal Neurobiology of Aging, UCLA professor of psychiatry George Bartzokis argues just that and says that a better working hypothesis is the "myelin model."
"The greatest promise of the myelin model of the human brain is its application to the development of new therapeutic approaches," Bartzokis said.
Like insulation around wires, myelin is a fatty sheath that coats our nerve axons, allowing for efficient conduction of nerve impulses. It is key to the fast processing speeds that underlie our higher cognitive functions and encoding of memories.
But the lifelong, extensive myelination of the human brain also makes it uniquely vulnerable to damage. The myelin model's central premise is that it is the normal, routine maintenance and repair of myelin throughout life that ultimately initiates the mechanisms that produce degenerative diseases like Alzheimer's. That is, the amyloid-beta peptide and the tau peptide, which is also implicated in Alzheimer's, as well as the signature clinical signs of the disease, such as memory loss and, ultimately, dementia, are all byproducts of the myelin breakdown and repair processes.
"The pervasive myelination of our brain is the single most unique aspect in which the human brain differs from other species," said Bartzokis, who is a member of the Laboratory of Neuro Imaging in the UCLA Department of Neurology and a member of UCLA's Brain Re
|Contact: Mark Wheeler|
University of California - Los Angeles