The GD thread on swhat to do with psychopaths has reminded me of something that has been bugging me for a while.
It is widely claimed that there is a chemical basis for depression, and a conclusive argument can be made for the statistical effectiveness of anti-depressant medications.
Similarly, Schizophrenia, and/or bipolar disorder, ADD, etc. seem to be generally treatable with medications, and in most cases medical science has a pretty good idea of why and how these meds work to ease the symptoms.
As far as I know, though, diagnosis is based only on observation of symptoms, and determination of proper medication (when several flavors exist) and dosage is largely a matter of trial and error.
Further, while these meds are effective on a statistical basis, it is not uncommon for particular patients to either derive limited benifits, or suffer unexeptable side effects.
Seems to me that if the problem is chemical in nature, you’d aught to be able to verify the diagnosis chemically. Doing so might yield a lot of insite as to why some patients respond well to medication, while others seem to gain little or no benifit. It might also suggest which medications are most likely to be effective for a particular patient, rather than the current “let’s see how this works” approach.
I admit that biology and psychology are not my strong suits. What am I missing here?
Because people have a (legitimate) object to getting their skulls split open to obtain a sample?
Because you can’t really prove it? After all, you can’t open the skulls of healthy people as a control group. In fact, the only people who’s skulls do get opened are already sick with a known neurological disease, thus tossing the validity of yoiur results out the ol’ window.
One thing that can be done (but isn’t because of the expense) are brain scans. These can reveal the nature of the problem in some cases. More importantly, they can show if the medication perscribed is going to help the patient just hours after the first dose (which is long before it can have a noticeable affect on a person’s behavior).
My friend’s father has developed a blood test for bipolar, schizophrenia and ADD. He has run successful trials and is in the process of selling it to a pharmaceutical company. I have no idea when it will make it to the market.
I take a cocktail of medications; periodically my psychiatrist has me get blood tests to see if I’m still at “therapeutic levels” of various chemicals.
Do those actually measure neurotransmitters? I think they generally just measure the drug itself, as well as liver function to make sure the drug isn’t killing you.
Iana physiologist, but my WAG is that
(i) there is often not one biochemical or simple cause for any one condition - depression could be from any number of chemical or external causes
(ii) the problem of biopsy as mentioned. Some conditions seem to be centered on a small part of the brain -one would have to accurately biopsy just that bit
(iii) many conditions such as schizophrenia are often poorly diagnosed, or misattributed. There can be disagreement between clinicians about what the appropriate label is.
(iv) the biochemical pathways involved often depend on very small amount of neurotransmittors or blockers. It may be difficult to assay them.
(v) In most cases the precise pathways or neurotransmittors are not known -
I know that blood flows to the brain,* which would make one think that it would flow back out. If that’s so, wouldn’t it pick up any sort of traces of what all is up in there? After all, the medication is making its way into the brain chemicals via the blood stream.
Though thinking about it, I’m not sure how it gets there given that there is Skull->Cerebrospinal Fluid->Brain, i.e. it floats mostly unconnected…so unless the our jugulars reorient back to join with the spine…?
This would happen if the brain was, uhm, a bag of fluid. But it isn’t. It’s full of nerve cells (and of fragments of nerve cells, your longest ones go from your brain to your big toes), which are bags of fluid and contain other bags of fluid inside.
The walls of those bags don’t just work through diffusion (like a tea bag); the majority of the wall is a double layer of fat (through which stuff that’s soluble in water can’t pass), and there’s occasional bits of protein allowing the water-soluble bits through or even “pumping” it (technical term, promise) in the right direction.
The chemicals that aren’t right may be inside the little bags that are within the nerve cells - that means getting through two celular walls plus the wall of the blood vessels before reaching the blood. And the passage through those walls looks like the tunnels out of NYC at peak hours.
That’s kind of the shorthand version for a whole branch of biochemistry.
As an example, there are at least 20 different genes associated with autistic spectrum disorders (ASD). Exactly how those genes are involved with ASD, and what the corresponding proteins do in relation to ASD is still years away from clarification. I will be involved in finding a biomarker for ASD soon, but there is no guarantee that the brain structuse associated with ASD will translate into a measurable change in a specific protein in the blood or urine.
There are many health issues that we don’t regularly test for- if your symptoms are apparent, what is the point? If you have, say, a herpes eruption, they arn’t going to test you. They are just going to treat you.
Furthermore, this opens lots of ethical concerns regarding things like jobs or schools wanting depression tests.
They do, however, do a variety of blood tests on people with depression to rule out any other causes like thyroid problems. “Depression” is pretty much defined as having life disrupting depression symptoms without an immedidate cause.