The seeds of mental destruction may be sown long before Alzheimer's disease visibly mars the brain, according to two new animal studies.
The brains of people with advanced Alzheimer's disease often shrink drastically while accumulating many deposits, or plaques, of a protein called beta-amyloid (SN: 8/5/95, p. 89). It's no surprise that the most popular theory for the origins of the disease points to these plaques.
The new studies, however, lend support to a different scenario. In it, an overabundance of free-floating beta-amyloid molecules catalyzes the creation of reactive forms of oxygen–called free radicals. These radicals initiate a cell-destroying process known as oxidative stress. According to this scenario, the protein plaques aren't the initial cause of Alzheimer's devastating symptoms but rather the result of the cells' desperate attempts to stem damage from the free radicals.
Although essential for life, oxygen can also be highly toxic, says Domen