• Question: Why do older people lose memory, and are the loss of memory and loss of sight related, and why do they happen simultaneously?

    Asked by to Ben, James, Jen, Michael, Susanna on 13 Mar 2013. This question was also asked by .
    • Photo: Jen Todd Jones

      Jen Todd Jones answered on 13 Mar 2013:

      I think Michael will probably have a good answer to this question! But it’s important to think about these two things as separate things, for the most part. Losing our sight usually means our eyes are failing with age and can start to happen even when we’re children, which is we wear glasses or contact lenses. Sometimes, though, brain damage at the back of the brain above the neck can cause problems with vision – here the eyes are healthy but the brain area responsible for processing vision has broken down.

      Losing our memory is a natural part of growing older, although we can even forget things when we’re children! By the time we’ve been alive for seventy years the brain has been working hard for a very long time, and it runs out of steam! It’s just a natural process for the brain to not work as well when we’re older, although sometimes it’s more severe than just normal ageing and people can develop dementia or have strokes which can cause memory loss.

    • Photo: Ben Brilot

      Ben Brilot answered on 14 Mar 2013:

      I’m afraid I don’t know about the actual mechanisms and Michael will undoubtedly give a much better answer about those. But evolutionary biology gives an explanation as to why you begin to lose all sorts of capabilities in old age:

      The simple story is that evolution doesn’t care how long you live for: it only cares about how many children you leave behind before you die. There’s always a risk that you might die before you’ve finished having any or all of your children. So evolution says that it makes sense to burn up all your energy and physical capabilities on having those kids when you’re young, even if once you’re done having kids your body and brain start to fall to pieces. The important thing was that you got to the point of having reproduced and left your genes behind after your death (in your children).

      The second part of the answer involves a classic (and maybe not 100% truthful) story about Henry Ford (the guy who invented and built the first “Ford” car). He once asked one of his employees to go to a car scrapyard and look at the old Fords and tell him which bits on the cars were still in perfect working condition. The employee found the parts that were still in tip-top shape and Ford changed how he manufactured these bits: he actually told his factories to make them WORSE. His point was, there’s no point in having one bit of the car that outlasts all the other bits by a long way, you’re spending money on making something that’s TOO good. Evolution has the same answer: there’s no point in designing your eyes to be able to see well for 200 years, because you’ll be dead long before then. So they evolve to be good enough for the period of time that you’re likely to be alive for. The same goes for your other brain functions (like memory), your muscles, your bones etc. So unfortunately that means that, much like a car, once we get old lots of things start going wrong with us all at the same time.

Comments