An article in today’s New York Times discusses recent findings that Alzheimer’s precursors are present at least 20 years before the onset of the disease.

The studies, published this month in the journal Lancet Neurology, found that the brains of people destined to develop Alzheimer’s clearly show changes at least 20 years before they have any cognitive impairment. In the Colombian family, researchers saw these changes in people ages 18 to 26; on average, members of this family develop symptoms of mild cognitive impairment at 45 and of dementia at 53.

These brain changes occur earlier than the first signs of plaques made from a protein called beta amyloid or a-beta, a hallmark of Alzheimer’s. Researchers detected higher-than-normal levels of amyloid in the spinal fluid of these young adults. They found suggestions that memory-encoding parts of the brain were already working harder than in normal brains. And they identified indications that brain areas known to be affected by Alzheimer’s may be smaller than in those who do not have the Alzheimer’s gene.