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Neuroimaging: Is the hype justified?

In order to gauge the hype surrounding neuroimaging in US society, consider the success of Daniel Amen. A specialist in brain disorders, Amen is a popular media personality, arguably the world’s most famous psychiatrist and a multimillionaire who has made a fortune out of using brain imaging techniques to help diagnose psychiatric conditions.

His franchise, Amen Clinics, operates around the US and is famous for its use of SPECT scans. SPECT stands for single photon emission computed tomography and measures blood flow in different organs by injecting a radioisotope into the bloodstream which illuminates the flow. Doctors often use the technology to detect cardiovascular diseases and tumors but Amen claims he can help patients with Attention Deficit Disorder (ADHD) by scanning their brains.

“The SPECT scans help us identify the type of ADHD the patient has so that we may make personalized treatment recommendations,” reads a statement on the FAQ section of his polished website. It isn’t hard to see why this would be attractive. According to the National Institute of Mental Health, ADHD affects an estimated 4.1% adults and 9% of children in the US, so such a diagnostic tool would be welcome if there were reliable evidence to support its use.

But According to many neuroscientists, there isn’t. Helen Mayberg, Professor of Psychiatry at Emory University and leading neurologist, tells me that Amen’s work is an example of medical entrepreneurialism which has capitalised on the hype surrounding neuroimaging and commercialised the technology before its clinical use can be justified by peer-reviewed science.

“There is not a study that Dan Amen has done for ADHD to justify that claim,” she says, “To make that claim an experiment should have been done by randomising different people with different patterns to different treatments and seeing what happens.”

Mayberg is a contributor to a review on neuroscience recently published in the leading bioethics journal, the Hastings Center Report. In her essay, entitled Neuroimaging and Psychiatry: The Long Road from Bench to Bedside, she recalls the naivety of the psychiatric profession she entered 30 years ago over the ease with which newly developed brain scanners could be used to diagnose mental disorders.

The ability of researchers to record the functional brain activity of psychiatric patients began in the early 1980s with the development of the first PET (Positron Emission Tomography) scans, which measure changes in cerebral blood flow. Over the past three decades neuroimaging has become increasingly sophisticated, with the availability of fMRI and SPECT scanners adding to the wealth of technology available. Yet with these advancements has come a recognition of the complexities involved.

“The expectation was very high that these new functional imaging methods would reveal new biological “truths” about major psychiatric disorders as well as about more elusive concepts like motivation, intent, and responsibility, which had previously been explored mainly by ethicists and philosophers,” writes Mayberg, “…It turns out that despite the seemingly limitless possibilities offered by evolving functional neuroimaging techniques, clinical applications are arriving quite slowly.”

In fact, with the exception of using PET and SPECT scans to confirm the diagnosis of Parkinson’s disease, Mayberg documents that there have been almost no neurological clinical applications for neuroimaging. Despite the early optimism, over time it has become apparent to researchers that clinical syndromes such as ADHD and depression don’t map onto the brain as well as expected.

“There has been a maturation to realise that the syndrome has component parts, but it’s not linear,” Mayberg explains, “It isn’t that a bunch of components affects certain areas of the brain and added together makes a syndrome.”

But as Amen’s case demonstrates, outside the laboratory the hype shows few signs of subsiding - a problem which extends further than the medical world. A strong movement has emerged which has successfully peddled the use of brain scans as evidence in US criminal court rooms where the fate, and in some cases the life, of the defendant is at stake.

In 2009 fMRI brain scans were accepted as evidence for the first time in the case of Brian Duggan, a convicted murderer and rapist sentenced to life for two murders in the 1980s. Duggan was accused of a third killing for which he faced the death penalty. His defence team called on Kent Kiehl, a neuroscientist at the University of New Mexico who has been performing brain scans on psychopaths for 20 years. According to Kiehl, his scans prove that psychopathic brains are different to normal brains, showing damage to the paralimbic system - a network of brain regions associated with regulating emotion.

Duggan underwent an fMRI scan in the hope that Kiehl’s research could persuade the jury he was a psychopath who couldn’t control his impulses. This, they hoped, would result in a lesser sentence of life in prison. The jury rejected the evidence and Duggan was sentenced to death. However, many neuroscientists felt that a dangerous precedent had been set, contending that there is not yet sufficient evidence to justify the use of such brain scans in the court room.

Psychopathy is normally diagnosed using the Hare Checklist, a set of 20 personality traits - such as pathological lying and superficial charm – which are measured in a structured interview. If the subject is deemed to have a sufficient number of traits he may receive a clinical diagnosis.

“Meeting criteria for psychopathy on the checklist is the basis for doing brain scans to identify what psychopathy looks like in the brain,” says Mayberg, “You need to know from those studies the pattern that on average all psychopaths on the Hare checklist meet, then you have to determine whether you can actually distinguish that pattern in individuals and how often you correctly spot a psychopath from their brain scan…It’s well-intentioned but it’s not ready and if you’re going to say it’s ready then you’d better have good data.”

Kiehl maintains that he wants to help remove the stigma against psychopaths, but there is a danger his work could have the opposite effect. In the US, criminals branded psychopaths are routinely denied parole on the basis of their diagnosis which is taken as evidence that they are likely to reoffend. Use of the Checklist is now so widespred even its inventor, Dr. Robert Hare, has expressed grave reservations telling NPR in 2011:

“I’m very concerned about the inappropriate use of this instrument for purposes that have serious implications for individuals and for society.” Now there is a fear the premature use of brain scans could make matters worse.

Furthermore, there is evidence to suggest neuroimaging can have an overly persuasive effect on the lay public, including juries, parole boards and psychiatric patients. In 2008, a study published in the Journal of Cognitive Neuroscience found that subjects were more likely to believe an explanation which contained neuroscience, even when the neuroscience information was irrelevant to the logic of the explanation.

“Explanations of psychological phenomena seem to generate more public interest when they contain neuroscientific information. Even irrelevant neuroscience information in an explanation of a psychological phenomenon may interfere with people’s abilities to critically consider the underlying logic of this explanation,” it concluded.

Yet despite their concerns, the authors of the Hastings Center Review are also keen to counter criticism which suggests all research involving neuroimaging is futile. “On the one end one of our concerns is that groundless promises are being made on the basis of neuroimages and that’s not a good thing,” says Erik Parens, a bioethicist and senior research scholar at The Hastings Center. “On the other extreme is the claim that neuroimaging is nothing more than 19th Century phrenology dressed up a bit. It strikes me that that too is an exaggerated and unfortunate claim.”

This view is shared by the Obama administration which earlier this year launched the the BRAIN (Brain Research through Advancing Innovative Neurotechnologies) initiative - a $100 million project which hopes to use neuroimaging to develop “a revolutionary new dynamic picture of the brain that, for the first time, shows how individual cells and complex neural circuits interact in both time and space.”

Helen Mayberg is equally positive. “I obviously could be considered an enthusiast, I’ve spent since 1985 doing imaging research so I obviously don’t think it’s a stupid method. It’s just harder than I was hoping but we make inroads,” she concludes.

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