Monday, February 23, 2004

Dietary supplements stop dementia in beagles? AAAS proceedings

In beagles, at least, there's evidence that diet can impact brain health ... | Dogs and medicine - Anti-oxidant anti-dementia therapy (for Beagles): Vitamin C, Vitamin E, alpha-lipoic acid, acetyl-l-carnitine.
... Carl Cotman and his colleagues at the University of California, Irvine, have been using beagles to investigate the effects of diet on the decline of brain function that accompanies ageing. Dogs are a useful stand-in for people in such experiments because the way memory declines in the two species seems comparable. Memory loss in dogs is accompanied by the formation of so-called amyloid plaques in the brain. Rodents, the usual stand-in mammals used in medical research, do not tend to accumulate such plaques as they age. In people, amyloid plaques are one of the symptoms of Alzheimer's disease.

... Dr Cotman wanted to know whether a diet rich in antioxidants, such as vitamins C and E, could relieve the symptoms of an ageing brain. Oxidative stress within the brain, which causes the production of molecules known as free radicals, increases with age. Free radicals can damage—and eventually kill—brain cells.

The results astonished the researchers. Not only did the antioxidant-rich diet halt age-related decline, it actually reversed it. While beagles on a normal diet continued to lose their cognitive abilities as they got older, those on the experimental diet showed improvements in learning and memory. These dogs could do much more complicated tasks, and made fewer mistakes. They could also re-learn tasks that they could do when they were younger, but had forgotten. And the diet (which, besides the vitamins, contained two food supplements called alpha-lipoic acid and acetyl-l-carnitine, that help to stop free radicals forming in the first place) also reduced the accumulation of amyloid plaques in the beagles' brains...
Ok. Why wasn't this a headliner in all the science summaries I review? There are so many implications of this research.

First, what's with dogs? I love dogs as much as the next geek, but they are starting to seem a bit odd. How much do they have in common with humans, anyway? In a previous posting I joked about dogs being a synthetic species designed to civilize pre-agricultural humanity...

Lunatic speculation aside, there are other implications here. Such as ...
  1. Would I add this to my elderly dog's dinner?
  2. Would I recommend it to everyone over 80 with memory problems?
  3. Will I (44yo) start taking it myself?
But first, the caveats (lots of them):
  1. Results like this are often misinterpreted or reversed on appeal. On the other hand, this isn't the first result of this sort, only the most dramatic.
  2. When a "natural" "supplement" alters physiology, it's a drug. These substances are being administered in doses much higher than in a human or canine diet. They're acting like medications, "natural" or not, they're drugs. Most drugs have side-effects and drug interactions, good sides and bad sides. These will be no exception.
    We don't really know what role antioxidants play in disease. In 1996 the CARET study found an increased rate of lung cancer among clinical trial smokers taking antioxidants. Since then researchers have wondered if antioxidants are a key part of the tumor surveillance system. So one big caveat is the relationship between Alzheimer's dementia and brain tumors. What if suppressing oxidative stress reduced the risk of plaque-associated dementia, but increased the risk of brain tumors? That would not be a great trade-off.
And now, the opinions:
  1. If my dog Molly, aged 14, didn't have a terminal disease, I'd add it to her diet. This is about as good evidence as we'll get for dogs.
  2. It's very tempting to consider for elderly people experiencing early Alzheimer's disease. A few tabs of ibuprofen, some antioxidants … . Dementia is a devastating disease, and many people would assume many risks to avert it. But see the caveats above. What if the therapy increased the risk of strokes, or lung cancer? What about interactions with other medications? Does one need all the supplements, or just some of them? How critical is the balance? Could an unbalanced regimen worsen the underlying process? How does this really work, anyway? Above all, how similar are beagles to people? We may not know the answer to these questions for decades.
  3. It's a huge leap from dogs to middle-aged humans. See all of the above. True, my memory isn't what I'd like -- but I'm probably at average risk for age 70-80 dementia, which implies significant impairment starting in about 10 years. Again, what if this antioxidant therapy knocked out a major component of the body's tumor suppression mechanism? OTOH, if I were at high risk for impairment within a 10 year time frame, I'd be phoning my neurologist now. Just to get them thinking.
Bottom line, very interesting. Alzheimer's is one of the major causes of dementia. Preventing Alzheimer's would, all by itself, resolve our social security and medicare crises. It would mean more people could be economically productive longer.

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