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I am having an epiphany. Maybe this "Alzheimer protein" is supposed to be the brain's defenses to something much worse. Maybe this protein is a "reaction" simi

I am having an epiphany. Maybe this "Alzheimer protein" is supposed to be the brain's defenses to something much worse. Maybe this protein is a "reaction" similar to skin rashes when it absorbs poison ivy's urisol. If Alzheimer was simply a deficiency of nutrients, I wouldn't think this way, but if it really is a protein that "can be cleared", why did it get there in the first place?

tdees40 11y ago
There's a growing body of evidence that Alzheimer's is really just "Type 3 Diabetes": http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769828/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769828/
jupp0r 11y ago
I'm not an expert, but human lifespans have only risen to relevant heights very recently. It's simply not enough time for it for evolution to kick in.
- jonnathanson 11y ago
  Average life expectancy is a commonly misunderstood (and widely misrepresented) concept. We hear things like "Humans really only lived into their 40s in the Stone Age," or what have you. This is untrue. Average (arithmetic mean) life expectancy was a lot lower because it was heavily skewed by infant mortality. Up until very recently, many more babies died within their first few years of life. We've dramatically improved our ability to produce and distribute food and medicine, which has had a profound effect on infant survivability. But we haven't actually lengthened the average life expectancy of an adult who survives the first few years of childhood by all that much. Point is, plenty of people have been living into their 70s, 80s, and 90s for as long as we've existed as a species. That said, the prevalance of diseases like Alzheimer's might be a fairly modern aberration, perhaps owing to lifestyle, environmental, and dietary factors.
  - phil248 11y ago
    Many more people are living in to their 70's, 80's and 90's than previously in human history. While our lifespan may not have increased much, the proportion of people reaching the extreme ends of our lifespan continues to rise. It's not just about infant mortality (not to mention death from childbirth).
    - jonnathanson 11y ago
      "Many more people are living in to their 70's, 80's and 90's than previously in human history." Correct, though largely (not entirely, but very largely) because the proportion of people living past age ~3 has skyrocketed. Correct for that factor, and our life expectancy is actually lower than it was in, say, mid-Victorian England. (Note, as well, that I'm referring to life expectancy and not, say, the potential maximum human lifespan).
  - daveguy 11y ago
    "That said, the prevalance of diseases like Alzheimer's might be a fairly modern aberration, perhaps owing to lifestyle, environmental, and dietary factors." Also somewhat owing to the recognition of Alzheimer's as a disease state (coincident with amyloid beta plaques) rather than just part of "getting old". The difference between "more prevalent" and "better identified" is difficult to determine.
    - jonnathanson 11y ago
      That's a totally fair point.
- ckarmann 11y ago
  For evolution, what is important is that you survive and have good health long enough to have offsprings. The vast majority of people, even in modern times, have their children before 50 years old (because women have this hard limit in their fertility). So there was never an evolution pressure to make our body function propertly after that time.
  - DenisM 11y ago
    Children who don't have extended family, such as grandparents, to care for them are more likely to die, either of of predators (if parents are out hunting) or of hunger (if parents stick around to protect their children).
tinco 11y ago
What I understood from the PopSci that passes HN every now and then is that the 'Alzheimer protein' is just some normal protein that the brain makes during normal operation every day. In your sleep the brain contracts and 'flushes it out' somehow, but over the years the protein accrues and you suffer dementia. Obviously that's super oversimplified and probably wrong, my source being skimmed over PopSci and all. Since dementia is a disease that happens at a late age, there doesn't need to be a reason why it is there. It happens a long time after reproduction, so its effect on evolution is minimal, worse it could even be evolved as a mechanism to curb older specimens in the species.
ejstronge 11y ago
I wish I had more time to follow up on this but I'll write what I can think of. Your core question is a good one and fundamentally raises the question of causality (which came first, the A-beta or Alzheimer's disease, AD? See ref. 1 for a 'simple' discussion). Interesting evidence comes from people with genetic mutations that decrease the levels of the precursor to A-beta (the protein associated with Alzheimer's plaques). People with these mutations are less likely to develop AD, suggesting that A-beta is related to the root cause of AD. The OP supports this evidence, as removing A-beta plaques ameliorates some memory loss. As a final, unrelated note, I don't know much dermatology but I haven't gotten the sense that our response to uroshiol is considered protective. Unlike A-beta, uroshiol is directly causative of its associated clinical symptoms[3]. 1. http://www.mayoclinic.org/diseases-conditions/alzheimers-disease/basics/causes/con-20023871 http://www.mayoclinic.org/diseases-conditions/alzheimers-dis... 2. http://www.ncbi.nlm.nih.gov/pubmed/22801501 http://www.ncbi.nlm.nih.gov/pubmed/22801501 3. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC294319/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC294319/
drzaiusapelord 11y ago
>Maybe this "Alzheimer protein" is supposed to be the brain's defenses to something much worse. What could possibly be worse? What are we seeing from non-Alzheimer sufferers that's so terrible? I don't think there's any evidence here that there's some benefit to it. Its a horrible disease. My dad went from occasional forgetfulness to completely falling apart in less than two years. He would get lost routinely, couldn't remember names, had no idea what time or day it was, and developed sundown syndrome where once 6pm hit he completely went mad. He would be angry at nothing and scream at the mirror. He would rant and ramble about his past or strange conspiracy theories. Towards the end, he lived in some weird nightmarish state almost all the time. Sundown syndrome became his norm. He died of cancer before it progressed past that point, but man, this disease is not just losing memories. It pretty much destroys your brain and acute dementia has a link with immune system dysfunction, so it eventually kills you, usually by pneumonia. I doubt there's any benefit. Evolution isn't this wonderful process. Its a lot of crap thrown at the wall and enjoying the stuff that works and dealing with what doesn't. There's no mastermind or clockmaker here. There are a lot of things that go wrong with human health that has no benefit.

tdees40 11y ago

There's a growing body of evidence that Alzheimer's is really just "Type 3 Diabetes": http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769828/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769828/

jupp0r 11y ago

I'm not an expert, but human lifespans have only risen to relevant heights very recently. It's simply not enough time for it for evolution to kick in.

jonnathanson 11y ago
Average life expectancy is a commonly misunderstood (and widely misrepresented) concept. We hear things like "Humans really only lived into their 40s in the Stone Age," or what have you. This is untrue. Average (arithmetic mean) life expectancy was a lot lower because it was heavily skewed by infant mortality. Up until very recently, many more babies died within their first few years of life. We've dramatically improved our ability to produce and distribute food and medicine, which has had a profound effect on infant survivability. But we haven't actually lengthened the average life expectancy of an adult who survives the first few years of childhood by all that much. Point is, plenty of people have been living into their 70s, 80s, and 90s for as long as we've existed as a species. That said, the prevalance of diseases like Alzheimer's might be a fairly modern aberration, perhaps owing to lifestyle, environmental, and dietary factors.
- phil248 11y ago
  Many more people are living in to their 70's, 80's and 90's than previously in human history. While our lifespan may not have increased much, the proportion of people reaching the extreme ends of our lifespan continues to rise. It's not just about infant mortality (not to mention death from childbirth).
  - jonnathanson 11y ago
    "Many more people are living in to their 70's, 80's and 90's than previously in human history." Correct, though largely (not entirely, but very largely) because the proportion of people living past age ~3 has skyrocketed. Correct for that factor, and our life expectancy is actually lower than it was in, say, mid-Victorian England. (Note, as well, that I'm referring to life expectancy and not, say, the potential maximum human lifespan).
- daveguy 11y ago
  "That said, the prevalance of diseases like Alzheimer's might be a fairly modern aberration, perhaps owing to lifestyle, environmental, and dietary factors." Also somewhat owing to the recognition of Alzheimer's as a disease state (coincident with amyloid beta plaques) rather than just part of "getting old". The difference between "more prevalent" and "better identified" is difficult to determine.
  - jonnathanson 11y ago
    That's a totally fair point.
ckarmann 11y ago
For evolution, what is important is that you survive and have good health long enough to have offsprings. The vast majority of people, even in modern times, have their children before 50 years old (because women have this hard limit in their fertility). So there was never an evolution pressure to make our body function propertly after that time.
- DenisM 11y ago
  Children who don't have extended family, such as grandparents, to care for them are more likely to die, either of of predators (if parents are out hunting) or of hunger (if parents stick around to protect their children).

tinco 11y ago

What I understood from the PopSci that passes HN every now and then is that the 'Alzheimer protein' is just some normal protein that the brain makes during normal operation every day. In your sleep the brain contracts and 'flushes it out' somehow, but over the years the protein accrues and you suffer dementia. Obviously that's super oversimplified and probably wrong, my source being skimmed over PopSci and all. Since dementia is a disease that happens at a late age, there doesn't need to be a reason why it is there. It happens a long time after reproduction, so its effect on evolution is minimal, worse it could even be evolved as a mechanism to curb older specimens in the species.

ejstronge 11y ago

I wish I had more time to follow up on this but I'll write what I can think of. Your core question is a good one and fundamentally raises the question of causality (which came first, the A-beta or Alzheimer's disease, AD? See ref. 1 for a 'simple' discussion). Interesting evidence comes from people with genetic mutations that decrease the levels of the precursor to A-beta (the protein associated with Alzheimer's plaques). People with these mutations are less likely to develop AD, suggesting that A-beta is related to the root cause of AD. The OP supports this evidence, as removing A-beta plaques ameliorates some memory loss. As a final, unrelated note, I don't know much dermatology but I haven't gotten the sense that our response to uroshiol is considered protective. Unlike A-beta, uroshiol is directly causative of its associated clinical symptoms[3]. 1. http://www.mayoclinic.org/diseases-conditions/alzheimers-disease/basics/causes/con-20023871 http://www.mayoclinic.org/diseases-conditions/alzheimers-dis... 2. http://www.ncbi.nlm.nih.gov/pubmed/22801501 http://www.ncbi.nlm.nih.gov/pubmed/22801501 3. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC294319/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC294319/

drzaiusapelord 11y ago

>Maybe this "Alzheimer protein" is supposed to be the brain's defenses to something much worse. What could possibly be worse? What are we seeing from non-Alzheimer sufferers that's so terrible? I don't think there's any evidence here that there's some benefit to it. Its a horrible disease. My dad went from occasional forgetfulness to completely falling apart in less than two years. He would get lost routinely, couldn't remember names, had no idea what time or day it was, and developed sundown syndrome where once 6pm hit he completely went mad. He would be angry at nothing and scream at the mirror. He would rant and ramble about his past or strange conspiracy theories. Towards the end, he lived in some weird nightmarish state almost all the time. Sundown syndrome became his norm. He died of cancer before it progressed past that point, but man, this disease is not just losing memories. It pretty much destroys your brain and acute dementia has a link with immune system dysfunction, so it eventually kills you, usually by pneumonia. I doubt there's any benefit. Evolution isn't this wonderful process. Its a lot of crap thrown at the wall and enjoying the stuff that works and dealing with what doesn't. There's no mastermind or clockmaker here. There are a lot of things that go wrong with human health that has no benefit.