A Dutch woman who reached 115 years of age and remained mentally sharp throughout life also had a healthy brain when she died, a new study finds.
The woman's brain showed almost no evidence of Alzheimer's disease. The finding suggests Alzheimer's disease and other forms of dementia are not inevitable, as had been suspected.
"Our observations suggest that, in contrast to general belief, the limits of human cognitive function may extend far beyond the range that is currently enjoyed by most individuals," said lead researcher Gert Holstege, a neuroscientist at the University Medical Center Groningen, in The Netherlands.
The results are detailed in the August issue of the journal Neurobiology of Aging.
At age 82, the Dutch woman made arrangements to donate her body to science after death. She contacted Holstege when she reached age 111, worried that her body was too old to be useful for research or teaching purposes. The neuroscientists reassured her that, contrary to her belief, they were particularly interested due to her age.
"She was very enthusiastic about her being important for science," Holstege and his colleagues write in the journal article.
Neurological and psychological examinations were performed when the centenarian was 112 and 113 years old. The results were essentially normal, with no signs of dementia or problems with memory or attention. Her mental performance was above average for adults aged 60 to 75.
When the woman died at age 115, her body was donated to science. Holstege's team found no signs of narrowing of the arteries, called atherosclerosis, and very few brain abnormalities. In fact, the number of brain cells was similar to that expected in healthy people between 60 and 80 years old.
The woman's brain showed little or no evidence of Alzheimer's disease. The neuroscientists found almost no deposits of so-called beta-amyloid, which are characteristic in Alzheimer's brains. The other abnormalities present, including "neurofibrillary tangles," were very mild, and would not have caused significant mental impairment.
Currently, there are more than 80,000 Americans 100 years of age or older, according to the U.S. Census Bureau. That number is expected to rise to more than 580,000 centenarians by 2040.
A recent study of a man who lived to age 114 found a combination of genes and lifestyle play a role in longevity, though the long-life recipe is far from clear.
As the number of people living to age 100 and beyond continues to increase, the researchers say, deterioration of the brain is not inevitable.
Video: Why We Age