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Monday, 21 January 2013

Mental Illness and Violence

James Holmes, the accused Aurora, Colorado movie-theater shooter


Reading Ann Coulter's article Guns don’t kill people, the mentally ill do I felt a lot of sympathy for her position.

I attended University in Italy in the late '70s, and I studied psychiatry as part of my Philosophy course.

The anti-psychiatry movement started by British psychiatrist Ronald Laing, which denied the existence of mentall illness, claiming that the whole family of the patient is ill and the psychiatric patient is only the scapegoat of the family's disease, was then very influential.

Italy's democratic psychiatry school of Franco Basaglia of Gorizia's Psychiatric Hospital was very popular. The political slant in Basaglia's approach was that the mentally ill is simply someone who chooses not to conform and integrate, a victim of society or, more specifically, of the political powers who need to emarginate dissenters (and he wasn't talking just about the Soviet Union but of Western democracies too).

I remember even attending, with other university students, a meeting with the patients of Arezzo Psychiatric Hospital, run by another psychiatrist of Basaglia's school, Pirella. Meetings between the hospital patients and the general public were regularly organized. And in these hospitals, the patients were free to go in and out.

The whole idea then was that psychiatric patients had been oppressed and terribly mistreated, that they should not be locked up and that the chance of their being dangerous was risible.

What these movements achieved, as well as influencing the way people look at mental illness, was a profound reform of psychiatric institutions, with the release into "the territory" (the Italian term) or "the community" (the English jargon) of many people previously admitted into mental hospitals.

We are all now familiar with many cases in which some people with psychosis have become a very difficult burden for their families, who can't cope with them and repeatedly asked for them to be re-admitted to a hospital and treated. In some cases such mentally ill people have committed suicide or murders.

This could be the reason why a new NBC News/Wall Street Journal poll, in which respondents were asked to apportion responsibility for the shootings that have taken place in Tucson, Ariz.; Aurora, Colo.; and Newtown, Conn. to various posssible choices of causes, reveals that
The second choice, selected by 82 percent as “a great deal” or “a good amount,” was “the lack of effective treatment for mental illness.”
The first choice was “parents not paying enough attention to what is going on in their children’s lives”, of which 83 percent said that was “a great deal” or a “good amount” responsible. Only 4 percent said “none at all.”

Guns only came in fifth, somehow vindicating Coulter's position, although the percentages were still high:
Tied for fifth place at 59 percent each was “assault and military-style firearms being legal to purchase,” and “the availability of high capacity ammunition clips.”
But the point is: is this scientifically founded?

Here I believe that, as much as the new psychiatric policies may have been failures, to find the right balance is extremely difficult.

There is a statistical fallacy which commonly confounds the issue here. The proportion of prison inmates who are mentally ill is rather high - some sources say almost 1 in 5 in the United States -, and according to a systematic review people with schizophrenia are about twice more likely to be violent than other people, but the proportion of psychotic people who commit violent crimes is extremely low: an Oxford Journals meta-analysis of 7 studies in different countries resulted in an estimate of 1 murder of a person unknown to the mentally ill individual per 14.3 million people per year.

The report concludes:
Stranger homicide in psychosis is extremely rare and is even rarer for a patient who has received treatment with antipsychotic medication. A lack of distinguishing characteristics of stranger homicide offenders and an extremely low base rate of stranger-homicide suggests that risk assessment of patients known to have a psychotic illness will be of little assistance in the prevention of stranger homicides.
We know that hindsight is easy, but prediction is a much harder business.

Psychotic killing of strangers is extremely rare, and rare events are difficult to handle statistically. Ben Goldacre explains it in his book Bad Science:
Let's think about violence. The best predictive tool for psychiatric violence has a ‘sensitivity' [accuracy in predicting correctly] of 0.75, and a ‘specificity' [accuracy in not over-predicting] of 0.75. It's tougher to be accurate when predicting an event in humans, with human minds and changing human lives. Let's say 5 per cent of patients seen by a community mental health team will be involved in a violent event in a year. Using the same maths as we did for the HIV tests, your ‘0.75' predictive tool would be wrong eighty-six times out of a hundred. For serious violence, occurring at 1 per cent a year, with our best ‘0.75' tool, you inaccurately finger your potential perpetrator ninety-seven times out of a hundred. Will you preventively detain ninety-seven people to prevent three violent events? And will you apply that rule to alcoholics and assorted nasty antisocial types as well?

For murder, the extremely rare crime in question in this report, for which more action was demanded, occurring at one in 10,000 a year among patients with psychosis, the false positive rate is so high that the best predictive test is entirely useless.

This is not a counsel of despair. There are things that can be done, and you can always try to reduce the number of actual stark cock-ups, although it's difficult to know what proportion of the ‘one murder a week' represents a clear failure of a system, since when you look back in history, through the retrospecto-scope, anything that happens will look as if it was inexorably leading up to your one bad event. I'm just giving you the maths on rare events. What you do with it is a matter for you.

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