'Commercial Genetic Psychiatric Tests Are Irresponsible And Harmful, Say Scientists'

Main Category: Psychology / Psychiatry
Also Included In: Genetics
Article Date: 17 Apr 2009 - 1:00 PDT

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The recent introduction of commercial genetic tests for susceptibility to psychiatric disorders is opposed by mainstream scientists as being 'irresponsible' and 'harmful', new research says. Companies in the USA have since late 2007 begun offering simple tests that claim to show how susceptible someone is to developing schizophrenia or bipolar disorder (manic depression) during their lives.

The tests use a similar procedure to those which measure the probability of risk for developing physical diseases like heart problems, diabetes or cancer. These involve people sending swabs from the inside of their cheeks to companies which analyse them genetically in labs.

A study by Dr Michael Arribas-Ayllon and Mr Andrew Bartlett, presented at the British Sociological Association's annual conference in Cardiff, UK, says that scientists think that the psychiatric tests are "a bridge too far too soon".

This is because earlier studies which claimed to have found single genes that cause schizophrenia, bipolar disorder and alcoholism have been discredited and withdrawn. Many scientists now believe that susceptibility to mental illness may be caused by a combination of several or many genes, and predicting susceptibility is too complex for commercial testing at present.

The study quotes other research which said that the tests may be harmful to patients because their over-simplicity made them inaccurate. A test which wrongly said that a person had genes which predisposed them to suicide might make them depressed or deeply anxious unnecessarily. A 'false negative' might also encourage someone taking psychiatric medicine to stop when they should continue.

At present several American companies are offering the service, which can also be accessed by people outside the US who go through their GPs. There is no obligation to have counselling when the test results come through.

In their study, entitled 'Complexity and accountability in psychiatric genetics', Dr Arribas-Ayllon and Mr Bartlett, both of Cardiff University, say that "the appearance of these biotech companies and their tests is anticipated to be the first wave of commercialization of psychiatric genetic research by the fast-expanding genetic testing market.

"Until recently, genetic testing had received little attention within psychiatry, but the development of genome-wide scans...has raised concerns about the poor predictive value of commercial testing."

Some researchers argue that this "may be harmful to patients, since the reduced complexity of the test offers limited or spurious predictability," the study says.

The study notes that scientists refer to "the complexity of psychiatric disorders in order to stress the poor predictive value of tests based on the simplicity of single 'genes for'.

"Genetic testing in its present form is therefore presented as scientifically and clinically irresponsible, a 'bridge too far too soon'."

The authors also point out that there is uncertainty over how genetic tests will be regulated. Regulations that govern clinical laboratories do not apply to companies offering genetic health testing since their products are not held to be medical but educational. These companies are operating in what amounted to a 'regulatory vacuum'.

In reaching their conclusion, the authors examined 35 papers published in journals including Nature, The Lancet, Human Molecular Genetics and the British Journal of Psychiatry.

However, the study noted that while scientists were willing to agree that the genetic basis for psychiatric disorder was complex when talking about scientific policy among themselves, they were less willing to do so when talking about science to the public.

This was because admitting that the genetic basis for psychiatric disorders was complex was useful for criticising genetic testing, and for avoiding the mistaken search for single genes causes of psychiatric disorders of earlier scientific papers. But it was also an admittance of uncertainty and confusion which scientists were less keen to exhibit publicly. "Scientists are reluctant to admit the uncertainties that accompany complexity," the study says.

The study also says that although scientists are opposed to genetic psychiatric testing, they have not given up the idea that genes play an important role in psychiatric disorders. By saying that many genes are involved, this allows scientists to continue to argue that genes are the basis for some psychiatric disorders, even though no genes have yet been found to support this belief.

Scientists instead rely on other evidence, such as studies of twins which seem to support the idea that a tendency to develop some psychiatric disorders is passed down genetically in families.

However, the Arribas-Bartlett study says that other researchers have criticised twin studies as having flawed methodology. The authors note that scientists are reluctant to come to the other conclusion - that the main causes of psychiatric disorders are environmental factors such as upbringing and inequalities within societies.

So the scientists new acceptance of the complexity of the genetic basis of psychiatric disorders is, the authors say, a modification of their belief in the genetic basis of illness and not a 'paradigm shift' to a belief in the predominance of environmental influences.

The research was funded by the Economic and Social Research Council as part of the work of its Research Centre for Economic and Social Aspects of Genomics.

Source
Tony Trueman
British Sociological Association