17 December 2012

Psychosis Not Preventable

Neither medication nor psychotherapy is effective in improving the prognosis for youngsters considered to be at high risk of developing psychosis, according to a major study just published.

The idea of identifying and treating young people at risk of becoming psychotic - because of a family history of schizophrenia, or because they're showing some mild symptoms - has become very fashionable lately. But can we really do anything to pre-empt the disorder?

In this trial, 115 "ultra-high risk" Australian subjects were randomized to three different treatment conditions, or if they didn't agree to treatment, they were just followed up to see what happened.

The treatments didn't work. . . .
The other lesson here is that even "ultra-high risk" folks usually don't get psychotic: only about 10-20% of them, in fact, became ill in the first two years of this study; the British results I mentioned are very similar.
So is this really "ultra high"? Relatively, yes it is; even a 10% risk is far higher than the chance that a random person on the street would have. But in absolute terms, perhaps not.
A concern here is that rounding these folks up, labelling and 'treating' them might make their lives worse, or even increase the risk of psychosis.  
From Neuroskeptic.

Genes, Enviroment and Developmental Biology

It has long been known that psychosis has a very strong genetic component, but since a large share of all genetic conditions lead to a phenotype (observable characteristic) via a gene x environment mechanism, it isn't unreasonable to think that genes that predispose someone for psychosis merely create vulnerability to whatever environmental triggers cause psychosis to manifest.

On the other hand, studies of the mechanisms of schizophrenia, which usually manifests in late adolescence, point to a process of neurological system reorganization that happens as part of the usual developmental process as being one of the key triggers for the onset of the condition in people who are genetically predisposed to it. 

So, unless a treatment actually suppresses the biochemical process of adolescence (something that is done in the case of some transgender individuals, so that irreversible adolescent transformations of the body into a gender mold that undermine gender reassignment efforts can be suppressed until the individual is old enough to make his or her own decisions about sex reassignment treatments as a chronological adult), the treatment may be powerless to prevent the genes involved in schizophrenia from being triggered.

Non-Treatment Benefits Of Early Diagnosis

Similar issues come up in efforts to diagnosis autism early in the hope of treating it, despite the fact that it isn't clear yet that any of those treatments really work.

Now, this doesn't necessarily mean that early diagnosis is a bad idea. 

Knowing that a serious mental health condition is likely to manifest at a particular point in someone's life helps families make sensible plans, even if those plans may be entirely non-medical in nature (e.g. arranging to have inheritances from a grandparent placed in protective trusts rather than distributed outright), or are purely of the harm reduction variety rather than constituting true "treatment" (e.g. keeping weapons out of the house where there is a risk that a psychotic condition may manifest).

How Do Treatment Myths Form?

But, these kinds of results do call into doubt approaches to dealing with these conditions (and the risk that they may develop in the case of individuals at high risk for them) that are practically articles of faith among members of communities of family members of affected individuals.

It is easy to see how these belief systems could form.  Any form of "treatment" whatsoever is likely to be 80%-90% effective even among the highest risk individuals, and a run of good luck in a small study can easily get better results than that simply due to random chance.  But, "success rates" at those levels don't actually mean anything.

How Much Risk Is Too Much?

The statistical issues involved are similar to those involved in cousin marriage or a decision of an older father to have more children. 

Both marrying a cousin and having a child at an advanced age greatly increase the risk of cogenital genetic problems for the resulting child.  But, a huge percentage of children in both cases are perfectly normal anyway, because the risks that are magnified by cousin marriage and advanced paternal age are so small in the absence of a risk factor.  Is a risk that is increased ten-fold or more worth heeding, if there is a 90% or 95% or 98% chance that eveything will be fine despite the heightened risks?  Those are decisions that scientistists and doctors can't make for people (or at least shouldn't make for people).

I personally have made medical decisions for myself to receive treatments with a chance of success in the 90% to 98% range, knowing that there is a real risk of serious side effects, when the benefit to be obtained if the treatment works well is great.

1 comment:

Anonymous said...

You might wish to update your thinking. A null-finding on one study might just mean that those strategies did not work. Recall, that there have been many, many studies on treating cancer. Many did not work, but increasingly we've discovered things that did.

The same is true of early psychosis. But in 2010, the first break thru happened. You can read about it here from the National Library of Medicne