A group of Dutch researchers report that a 115-year-old who remained mentally alert throughout her whole life had a healthy brain that showed no signs of Alzheimer's Disease or other forms of dementia.
den Dunnen et al had the unique opportunity to evaluate the woman's performance on psychological tests just a few years before she died, and then later to examine her brain at autopsy.
They say that their findings, which are due to be published in the August issue of the journal Neurobiology of Aging, call into question long-held assumptions about the cognitive decline and neurodegenerative diseases associated with aging.
In 1972, Henrikje van Andel-Schipper, who was then aged 82, gave written consent for her body to be donated to the University of Groningen for the purposes of research and teaching. Nearly 30 years later, she contacted the researchers again, asking if her body would still be useful to them after she had died.
Subsequently, she underwent a series of neuropsychological tests, starting in 2002. When they met her, the researchers found that she had very poor eyesight, but was otherwise "an alert and assertive lady, full of interest in the world around her, including national and international politics and sport."
Her performance on the tests was initially very good: her scores were above average, compared to healthy adults of 60-75 years of age, on tests for attention, working and semantic memory, verbal reasoning and mental arithmetic.
The woman died on 30th August, 2005, aged 115. At the time, she was the oldest woman in the world. Her body was immediately taken to the dissecting room at the university, and the autopsy began some 2 hours after death.
Examination of her brain showed none of the neuropathological hallmarks of Alzheimer's - there were no beta-amyloid plaques whatsoever, and only a negligible number of Tau neurofibrillary tangles. These were found mainly in parts of the hippocampus (top, and above left).
Furthermore, the number of cells in a part of the brain called the locus coeruleus was estimated at 16,500 (above right), which is comparable to the number of cells found in healthy people under the age of 60.
It is generally assumed age-related cognitive decline is a normal process that is common to all people, and that Alzheimer's Disease is an inevitable consequence of aging; the risk of Alzheimer's increases exponentially past the age of 65, and affects more than 1 in 6 people aged over 80.
Although this is just one case study, it may lead researchers to reconsider some of their assumptions about Alzheimer's, because it shows that cognitive function can remain unimpaired far beyond the age at which they normally decline, and that Alzheimer's and other forms of dementia are not necessarily inevitable.
Ironically, the woman weighed little more than 1.5kg at birth, and was not expected to survive for long. On autopsy, a tumour of 7cm in diameter was found in her stomach, but the authors suggest that if she had not died from cancer she could have lived for several more years.
The authors conclude that "this is consistent with the idea that centenarians (people who live longer than 100) do not die from 'old age' but from a specific disease." They argue that genetics probably played a role in the woman's longevity - her mother died at the age of 100, her maternal grandparents lived to 80 and 85, and her two brothers and sister lived to 72, 82, and 80 respectively.
den Dunnen, W., et al. (2008). No disease in the brain of a 115-year-old woman. Neurobiology of Aging. DOI: 10.1016/j.neurobiolaging.2008.04.010
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What was her lifestyle like...drinker, smoker, jogger, vegan, hedonist?
Fascinating, but I wonder if anything can really be called into question on the basis of a single outlier?
caynazzo: There's nothing in the paper about her lifestyle.
Ian: Of course, she could be an exception to the rule. But the brain is full of surprises, so we shouldn't really make assumptions in the first place.
Like so many diseases traditionally associated with increasing age, if you can make it over the "hump" in style, you have proved your fitness. Now that my VW is at 130K, I expect it to last many more years. The ones that fail usually do so ~100K. Same for people.
It's true that you shouldn't throw out an entire theory on the basis of one case. But remember that all scientific conclusions are tentative until new evidence is found that refute them. Such as the famous example of "all swans are white", which is no longer valid once someone sees a black swan. So you have to rethink your theory, perhaps throw a boundary condition or two in (most swans are white, or swans of a certain age are white, etc.)... It's probably obvious at this point that I teach research methods. And I would never tell my students to drop an entire theory because of one case study, but a case study can give you valuable information that can lead to new (and large sample) studies of a phenomenon.
Don`t forget some of the most important insights in neurolinguistics were arrived at based on case studies by Broca and Wernicke.