Will Longer Life Leave Us All Demented?

Better preventive care, innovative surgical techniques, improved nutrition, and accessible pharmaceuticals have all had a hand in increasing the lifespan of Americans. Recently, research on caloric restriction and Resveratrol has provided science with additional tools to increase longevity. But what guarantee do we have as to the quality of that longer existence? Do we really want to live long, only to end up in cognitive decline in a rest home or mental facility? A study published in this month's PLoS Medicine examines the incidence of dementia at the end of life.

From Yahoo news:

It's unlikely that medical science will find a way to completely prevent dementia and cognitive impairment among the very old, Dr. Carol Brayne of Cambridge University and colleagues note in the October issue of PLoS Medicine. "Researchers may be doing those who are aging now and themselves a disservice in the future if they assume, and project to the public, that dementia and cognitive impairment can be prevented altogether during increasingly long lives," Brayne and her team write.

(Continued under the fold....)

Dr. Brayne and colleagues wanted to determine the prevalence of dementia at the end of life among a large group of people, and what factors (socioeconomic, education, gender, locale, etc) were influential. They analyzed data from 13,004 over-65 year old people in a 10-year study including both men and women living in Wales and England. Results indicated that 30% of participants were suffering from dementia when they died, and the likelihood of being demented at the end of life climbed as the person aged. 6% of people 65-69 had dementia while 58% of people 95 and older had dementia.

i-e354d6ec6d4dfc9e5f54b6758503a5cc-plos graph 1.bmp

Furthermore,

Having more education and belonging to a higher social class reduced the risk of dying with dementia, but the effects were small once the researchers controlled for other contributing factors. More educated, wealthier people live longer, Brayne and her team note, so the effects of aging likely weakened the effects of schooling and class.

There was also a slight differences in the incidence of dementia between men and women at certain age groups, but not others (see below).

i-f0545980ffd69e3d3f836e9533855f19-plos graph 2.bmp

PDF available from PloS Medicine here.

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By Big Bang hunter (not verified) on 02 Nov 2006 #permalink

I am willing to bet a lot of people have said that the odds of anyone extending their life significantly was just as unlikely. Its probably not "impossible" to prevent dimensia, but it might take several generations before there is an effective treatment for the full range of causes, which unfortunately leaves us in a seriously unfortunate position. It should be noted however that a number of the "causes" are tied closely to the reasons for aging in the first place and the lack of the same class of DNA repair mechanisms present in some species, especially a few plants, that would undo a lot of those causes. The real problem is that the most obvious means to "extend" human life span deal with adjusting the mechanisms that trigger aging, but those "exist" precisely because of a lack of the robust DNA repair systems. We may end up trying to "solve" the problem backwards, like tying ropes around the outside of a building to hold the walls together, while the reason the walls are falling down is because the entire structure itself is built on quicksand. We need to figure out how and "if" the foundation can be fixed, then worry about extending life spans into ranges that tend to promote dimensia and cancerous cell development.

After reading the report, I noticed the authors neglect a couple of major factors - nutrition and exercise. The authors use the word nutrition once in the entire paper and that's in the discussion stating that perhaps it should be considered. They don't discuss exercise at all. Yet, both of these are well established as contributors to late life cognitive ability. Overall, the study is important and interesting but it seems a little fatalistic. I choose to believe that I have a little more control over my late life mental state.

There are so many different types of dementias. There is a cortical type (e.g Alzheimer's, Pick's disease), sub-cortical (Parkinson's ) and also a mixed type. The causes for all these 3 types are different. I don't think it is very easy to explain the factors which can prevent dementias from occurring . I know that some of the dementias (especially Alzheimer's) is hereditary. So, if you are genetically predisposed to a certain type of dementia, then no matter what you do (eat good food, read, exercise ..basically keep your brain healthy), you might end up becoming demented!

By vijayachandra (not verified) on 04 Nov 2006 #permalink