mkrishnan said:
I don't think anyone on the cognitive side of dementia research would disagree with that. We just think that a combined approach is better than a purely biological approach, because, while we believe in reductionism, it is not necessarily true that biochemistry is always the most transparent language to discuss mental disorders in. If you push the reductionist thinking all the way to its extreme, then Alzheimer's Dementia is a particle physics problem, isn't it?
You are, of course, correct...There's a certain point when reductionism, while theoretically accurate, is no longer pragmatically useful as a thought mechanism. And there are times when a macroscopic view, like a cognitive approach, makes sense for treatment or understanding.
The clearest example is psychotherapy. Clearly, psychotherapy is useful, but it does have a molecular and cellular basis. It is sometimes more effective than drugs though, because for reasons we are only beginning to understand, it causes many neural responses that can integrate in a beneficial way. Drugs are chosen to be specific and, without a very large cocktail that would have many side effects, it would be difficult to target all of the various brain regions that talk therapy does.
However, for diagnostics, cognitive studies are a little bit fuzzy. One could diagnose depression in two different people who have the same psychological symptoms. However, we can't be certain that it's the same disease, as far as its causes. The root causes must be physiological changes, and while effective treatments can arise from cognitive approaches, diagnostics are, ideally, physiological in nature.
Alzheimer's is a really good example. By the time you see many cognitive changes, the disease is already far along. There are hypotheses, though, that amyloid beta might be building up for years, even decades, before any serious symptoms are noticeable. Of course, the Nuns study, which noticed that handwriting could be a good predictor for Alzheimer's is very interesting...It's just that handwriting and other cognitive markers are so complex that they can be affected by a million variables--making them poor markers, in general, as far as I know.
However, I'm sure there are some functional measures that might be good correlates. I'm going back and forth on this, but I'm trying to work it out in my mind, as well. If Alzheimer's uniquely and specifically brings about a certain change, then it could be possible to use that change as a marker. I still think that psychological markers are weak, but quantifiable systems-level markers might be more useful.
With Alzheimer's, which seems to be brought on by physiological changes independent of psychological effects and sensory experiences, it would seem treatment by talk therapy or other psychological treatments would not be effective...Who knows, though. There is the cognitive reserve theory, which makes a lot of sense--In other words, crosswords are prophylactic.
mkrishnan said:
FWIW our lab looks at biomarkers too. Although we are more interested in process changes and functional measures. I think its fair to say the great range of non-pathological human behavioral / cognitive individual differences are based in functional differences and not structural ones, and that by extension, those functional differences (which may not correlate to the presence of any unique compounds or any compounds in unique locations) are probably also pretty important as a substrate to pathology.
I dunno...What's there to bring about the functional changes? It has to be something structural. Whether it is a difference in sensory input, wiring, membrane protein expression, etc., something has to cause the change, right?
I guess my problem with functional definitions is that they must, by nature, ignore the cause. Functions are a product of structure, as far as I know, and so it's most useful to focus in on the structure, if you want a clear understanding of what's going on...
If you can dispute this claim of mine, I would greatly appreciate a different perspective.
mkrishnan said:
But I'm not aware of anyone who believes AD has no biological basis....
Of course not, and you know that I'm not aware of anyone who does so either.
I was pointing this out for the benefit of those who don't think about Alzheimer's pathology--or other pathologies--on a regular basis, the way that we probably do.
