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ChristianKl comments on A Medical Mystery: Thyroid Hormones, Chronic Fatigue and Fibromyalgia - Less Wrong
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I know you're teasing, but physical trauma and drowning aren't unexplained, sickle-cell anaemia is very much explained by germ theory (malaria defense), controlling nutrition and energy usage is probably exactly what the thyroid system's for in adults, hormonal imbalances are what I'm talking about, and OK, I'll give you cancer. For now.
In fact I think I'm trying to add a coda to the germ theory. One reason that ancient control systems would just spontaneously go horribly wrong is if they were in a continuous state of desperate patching and hacking to deal with an intelligent and adaptive enemy. And pathogen evolution is just that.
That's why we see in living systems a combination of beautiful engineering and idiotic kludge. Like a BMW with a tin can lid riveted on one side. The explanation is likely to do with bullets.
Therefore we expect infectious cause for this sort of horror. But we don't find it. Where is it? In the past. Today's fuckups are yesterday's hastily constructed defenses.
Not of course to forget the environment. If we've got a hideously complicated and sensitive chemical control system that's been tested to death really well in the presence of all the usual chemicals, and suddenly we start adding new chemicals, what then?
Notice that a lot of cancers are caused by novel chemicals, and a lot of them are caused by viruses.
Presumably all the viruses and bacteria and fungi and cancer cells are themselves generating novel chemicals in order to screw the system up so it can't kill them.
I'm not saying. I'm just saying....
Infectious cause, immune defence, recent environmental change, recent adaptation to environmental change.
The four horsemen of unexplained diseases.
One thing I don't claim is vitamin deficiencies. But they fit into Cochran's framework nicely.
And I'll give you that if you deliberately drink far too much water even though you'd really like to stop and then it kills you, you've got a genuine 'somatoform' disorder.
Except even then. That sounds like the sort of thing people do on drugs. I wonder how those drugs act on the mind?
Physical trauma doesn't have to be explained, it's an explanation. In cases like broken legs it's a pretty straightforward explanation. In other cases like depression, it get's more complicated.
An explanation is a chain of causal links, where each one is verified under interventions. If I hit you with a sledgehammer, your leg will break, and we know why, and it's not that my anger causes 'stress', and that breaks your leg by magic stress-property, because I'm stressed too, and yet my leg never breaks.
A vague correlation is not an explanation. It's a sign that you should look for one. Sure if I attacked you with a sledgehammer, you might get depressed. But why?
Depression in patients with acute traumatic brain injury :
Major depression occurs in about one-quarter of patients after traumatic brain injury. This is the same frequency as in other major disorders such as stroke. Major depression appears to be provoked by one or more factors that include poor premorbid social functioning and previous psychiatric disorder or injury to certain critical brain locations.Depression among older adults after traumatic brain injury: a national analysis.:
TBI significantly increased the risk of depression among older adults, especially among men and those discharged to a skilled nursing facility. Results from this study will help increase awareness of the risk of depression post-TBI among older adults.It's plausible that the trauma kills neurons and thus creates depression. It's also possible that some fascia tenses up and produces problems. It's possible that it produces Sensor Motor Amnesia. It's possible that it creates problematic inflammation.
There are a lot of plausible mechanisms to choose from.
Trolling or eyerolling? You decide!
X-D
Agreed. Thanks. It was more a sort of philosophical point about the nature of explanation. We might be able to tell which of these counted as an explanation by intervening later on in the proposed causal chain and seeing if the same results obtain.
As far as the philosophy goes, for most successful interventions in health care we don't really know how they work.
Depression usually comes along with increased inflamation of the gut. Depression medicine that's intented to target the brain because of chemical imbalance, also hit's targets in the gut.
Does that mean I'm certain that those drugs fight depression by having positive effect on the gut? No, I'm not certain of that, but it's an open possibility.
"Explanations" in general aren't good at predicting outcomes for drugs. That way so many clinical trials fail. The only way that seems to work is to gather empiric evidence for treatments. That way you know whether the treatment works but not why it works.