More good questions!
Ok......again, I'll take a shot. Robin and Wesley (and others), hopefully will also add their comments.
Ok....memory loss associated with MS. Memory and cognitive processes in the brain are very strange complex mysterious things. Studies have been done and are still ongoing (not just in relationship to MS) about just how the brain "works". The most that can be ascertained is that the brain DOES work very similarly to an actual computer. (My guess is the reason why Wesley, Robin and I have such deductive reasoning abilities, it appears, is because if you noticed, we all are good with computers). When data is stored in a computer, it is fragmented and bits and pieces are or can be stored anywhere and everywhere on the hard drive. It "appears" that the data has been stored somewhere in one piece, but that is not the case (if you will recall, we used to even have to run a "defragment" program on our computers every so often to try to gather pieces of data together as much as possible). The same with the brain. Memory appears to be fragmented when it enters the brain. Bits and pieces of knowledge and memory are stored all over. There appears to be no rhyme nor reason that can be currently ascertained. Now, earlier I mentioned how the cerebellum at the base of your skull does the "processing". Think of that as the CPU part of a computer. Not only does it process and send messages regarding body "actions" to the other parts of the brain (i.e. various parts of white matter), it also sends out cognitive, memory and knowledge input to other parts of the brain.
It "appears" that as far as certain types of cognitive processes are concerned, some of those processes seem to be concentrated in the frontal lobe of the brain (white matter). Here is another good visual for you:
http://www.neuroskills.com/index.shtml? ... ntal.shtml
Since as we mentioned before, MS tends to interrupt processes in the white matter, if it interrupts processes in the frontal lobe(s), it's likely that memory, etc. will be affected.
As far as similarity between diseases............I know what you mean. Welcome to neurology. They overlap, don't they? That's why you see me say "where does one thing leave off and another begin"? It is definitely extremely difficult to put a boundary around any one neurological disease. There are only "slight" differences. And unfortunately, since most neurological diseases are still of a great "mystery", there may not be any good answers that can be provided.
Preprogrammed cell death is a regular process of the body that needs to be done. Cells in the body get old and need to die. You may have heard that the human body totally regenerates itself like every 7 years or so. Our bodies are constantly renewing and replacing our cellular structure. It has to. Otherwise, if the human body had NO way to regenerate, none of us would live very long at all, just speaking total lifespan. A few years at best. So preprogrammed cell death is a natural function of the body. Where the problem comes in is if this cell death process is "skewed" somehow. Hence, MS, Parkinson's, Alzheimers and many other neurological diseases will/may refer to some dysfunction or another of cell death.
Some main differences, though, between the diseases you mention are the biological locations that are affected. Again, that's putting it as simply as possible. MS targets specific minute cellular structures of the body (in the brain and spinal cord), Parkinson's results from dysfunction in different biological locations, etc. etc. Now, this gets very detailed and right down to microsopic minutia, but to keep it simple, what I've had to do is remember that it's not the terminology used to describe the physical result (symptom manifestation) from any particular dysfunction that matters, it's the biological location in the body that tells the difference between neurological diseases. And to go just one layer deeper on that, there are also small differences in which particular "process" in the body that is somehow dysfunctional that tells the tale. Parkinson's loss of function (i.e. tremors) appears to come from the body's almost total inability to create and utilize dopamine, and/or it destroys dopamine. MS's loss of function (tremors) appears to come from damage to a part of the brain that helps to control that type of movement (again, the message/transmission isn't getting to a part of the body quickly enough or clearly enough). The damage result "appears" the same from the outside (i.e. both have tremors), but the reason WHY is different.
And again, the same with "dementia". Alzheimers dementia comes from a different type of damage going on inside the body than what is happening with MS.
Now....having said ALL of that...........remember, the likelihood of tremors with MS being anywhere near as severe as the tremors associated with Parkinson's are so remote as to not be comparable. The same with dementia. You can't/shouldn't make a comparison between any RARE dementia that may be said to be associated with MS, as the same degree of dementia as what happens in Alzheimers. It's not comparable at all.
Are the researchers looking for "links"? I'd say yes, but so far, there doesn't appear to be too many, other than the fact that neurological diseases themselves overlap, simply because neurological diseases are isolated to the nervous system. That's the "link" that you can make. They are all diseases of the nervous system. It's a systematic link, not necessarily a "disease" process link. There are generalities, of course, such as dietary and supplement considerations if you have any type of neurological disease, but aside from that, so far, the minute details of the different neurological diseases are somewhat different from each other. But....it's still venturing into the unknown at this point in medical research. (Maybe that's why they come up with analogies all the time between medicine and space exploration! )
But we need to make sure that the ideas above are not forgotten - I would have thought that a professor of neurology looking for a Nobel prize would do well to pull together the excellent ideas exchanged above.
I think you'll find most of us agree with you there, bromley!! That's what you will see a lot of us say time and again. We even had a discussion on this website about the Nobel prize. And actually, I think you would be pleasantly surprised at how many people ARE assertively expressing our thoughts and ideas and questions to the medical community!
EDIT: I'm editing for typos again!