A friend of mine asked me a question relating to aging and memory loss. I thought that it would make a great blog topic, so I put my response here! ^.^
Aging is caused by two factors, both linked to cell division. Cells divide and grow for three purposes: growth of organism, replacement of dead/dying cells, and fortifying the immune system during an infection. Obviously as adults, we no longer grow, so our cells must divide in order to replace other cells. The process of a cell division is called mitosis.
As we age, we lose our ability for our cells to divide. -Cells have the ability to divide continually for a certain amount of time, then as we age, this ability gets lost. This is the reason why older individuals have a very hard time healing, whereas young kids seem to heal overnight!
Why do we lose the ability to divide? The theory is that each time we divide, our cells have to make a new copy of DNA to go into the next cell, right? Well, each time we make a copy, we lose bits of DNA, called telomeres in the process. These telomeres protect the actual ends of the DNA, and keep it from going crazy and haywire. Because they get shorter each time a cell divides, eventually, they run out. The current theory is that THIS is what causes aging.
Think about a photocopy of a sheet of paper. In the "first generation," the original copy and the photocopy don't look very different. But if I keep photocopying the copies of paper, eventually, I begin to lose resolution, things get blurry and fuzzy, and after a long amount of time, you begin to start losing important bits of information.... signs of aging.
-Incidentally, this is also a problem that we are encountering with the cloning process. It seems that when you make a clone using "old" DNA, the organisms that come from it also seem to be "aged" as well, and can suffer complications.
Now the mechanism behind memory loss is different. In general, our brain cells and nerve cells don't divide. This is why when someone has nerve damage, it's usually permanent. There's a lot of research on nerve tissue regeneration (and a whole lot of discussion on stem cells), but right now, we're not there yet. Anyways, we retain a set number of brain cells that retain our memories. However, like the rest of our body, eventually, the "machinery" runs down, and our cells begin to die. Because we can't replace these cells, our memory starts to go away because we don't have as many brain cells as we did before.
*As a sidenote, when you drink alcohol, you kill brain cells. The theory that you get stupider the more you drink? Yup. 'fraid so.
Although another new theory has come out in regards to memory as well. The idea is that we have not necessarily lost our memory cells per se, but we have become desensitized to the things around us. We lose our awareness of the things such as routines, and therefore, do not commit them to memory like we did when we were younger. Studies have shown that when older individuals go through mental exercises to practice mental awareness, they can actually increase memory retention!
So memory loss is actually caused by two things: dead brain cells, and loss of mental awareness and acuity.
What do we do about it? Go to your nearest biotech company and present them with a big fat check to help stimulate the economy of course!
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