New Theory of Alzheimer's: Brain's Memory Center Is "Overworked"

By Eliza Strickland | April 7, 2009 1:23 pm

brain MRIYoung adults with a genetic variant that increases their chance of developing Alzheimer’s later in life also have increased activity in the section of their brain devoted to memory, a new study has found. Researchers say the results suggest that the memory portion of the brain, the hippocampus, may eventually get worn out from a lifetime of overuse.

Researchers conducted fMRI brain scans of 36 volunteers, half of whom had at least one copy of the gene, known as APOE4. “We were surprised to see that even when the volunteers carrying APOE4 weren’t being asked to do anything, you could see the memory part of the brain working harder than it was in the other volunteers,” [study coauthor Christian] Beckmann said…. “Not all APOE4 carriers go on to develop Alzheimer’s, but it would make sense if in some people, the memory part of the brain effectively becomes exhausted from overwork and this contributes to the disease” [Reuters].

However, the researchers note that they’re far from proving this hypothesis, and say that it’s impossible to tell whether the extra activity contributes to Alzheimer’s symptoms later on or is just a sign of inefficient brain circuitry in the hippocampus [New Scientist].

The researchers hope their work could eventually lead to the development of a simple method to identify people at increased risk of developing dementia. They could then potentially be offered early treatment and lifestyle advice…. Researcher Dr Clare Mackay said: “These are exciting first steps towards a tantalising prospect: a simple test that will be able to distinguish who will go on to develop Alzheimer’s” [BBC News].

In the study, which will be published in the Proceedings of the National Academy of Sciences, researchers stress that not everyone with the gene variant develops Alzheimer’s, and say that people with one copy have four times the normal risk and those with two copies have 10 times the risk. While experts caution against leaping to conclusions from the new study, they welcomed the findings as significant. “The causes of Alzheimer’s are complex – both genetic and environmental – and if we can understand these better, we can enhance efforts to help people lower their risks” [BBC News], says Rebecca Wood of the Alzheimer’s Research Trust.

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Image: iStockphoto

CATEGORIZED UNDER: Health & Medicine, Living World
  • NewEnlandBob

    *** ALARM BELLS ***

    Some of this looks like wild speculation based on nothing.

    “…results suggest that the memory portion of the brain, the hippocampus, may eventually get worn out from a lifetime of overuse”

    This is not a knee. What basis do they have for ‘worn out’?

  • Jumblepudding

    As somebody with a more vivid recall of childhood events than others, and a family history of alzheimers, this makes me wonder if I have this gene.

  • YouRang

    I have to ask: What constitutes being overworked? What is the average amount of overwork; what is the median (first moment) of the amount of overwork? Were the assessments of amount of work done blind (no knowledge of aPOE4 status)? Was there adjustment for “IQ” (yeah I know IQ is not a good scientific measure of much of anything, but did they try)? Were there multiple kinds of memory chore (eidetic/non-eidetic, categorization/random, etc).

  • Kin

    Sounds to me as if it just indicates that its not working *right* than overwork. Well it’s a stretch of journalism, I guess, because it has nothing to do with people who have great memories, nor did the study study the memories of those with the gene in the layperson’s sense.

    Nevertheless, very interesting.

  • Thomas Nofziger

    Unless the APOE4 gene provides a pathway to early glial senescence, and thus premature diminishment of support for neurons in the hippocampus, I’d say there’s something else going on here.

    What this study may actually bear out is just how likely it is that researchers at Brown University, lead by Dr. Suzanne de la Monte, are correct in their theory that Alzheimer’s Disease is a product–an epiphenomena–of a cerebral condition they refer to as Type III diabetes. Note that I’m not referring to the gestational type which is often referred to Type III.

    ApoE is a target gene of liver X receptor, a nuclear receptor member that plays roles in the metabolic regulation of cholesterol, fatty acid, and glucose homeostasis. With APOE4, there are increased odds that the capacity for glucose homeostasis will deteriorate with chronological age, that cerebral diabetes may then ensue, and that all the symptoms discussed endlessly in both literature and the popular press will show their ugly heads.

    I just noticed that listed above is a blog entitled : “Cutting calories could drastically boost senior citizen’s memory”. Should this be the case, we have even more evidence of the need to control cerebral glucose metabolism. Note that some regions of the brain produce more insulin than do Beta Cells, those which 65% to 80% of the 1,000,000 or so Islets of Langerhans in the pancreas.

  • Pinkie Walpole

    I have an extraordinary memory – I seem to remember absolutely everything and after half a century of witnessing people’s amazement and being considered almost a freak, I panicked. What if one morning I woke up with no memories whatsover? I wrote to Prof. Eric Kandel (who won the Nobel Prize in 2000 for his work on memory) and he told me that memory will not exhaust – to rest assured.

  • Muggsie Esper

    My husband’s brain is seldom paying attention to what is currently going on. His brain is always thinking of completely unrelated things that have happened in the past or may happen in the future. I think this constantly thinking for no reason whatsoever may be much more the factor than someone who has a good memory. His memory is very poor, and it is getting worse, but his brain never gives him any quiet time.

    I think you people with good memories have nothing to worry about.

  • Jean-Victor Côté

    Maybe the overworked hippocampus is the result of trying to compensate for a faulty memory or maybe the hippocampus is directly affected by the disease.

  • http://www.elementsofmemory.com Trevor

    I agree with NewEnglandBob – seems like speculation. For more information, including a free report on memory improvement, check out http://www.elementsofmemory.com .

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