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Diagnostic neuroimaging for psych patients — ethical?
Costly scans may not reveal anything useful
Does a psychiatrist offer diagnostic neuroimaging to their patients and claim to diagnose and treat psychiatric disorders using the results?
"It's misleading to tell patients that we can identify what psychiatric disorder they have, or don't have, by looking at the activity in their brains," says Seth J. Gillihan, PhD, visiting assistant professor at Haverford (PA) College and former assistant professor of psychology at the University of Pennsylvania's Center for the Treatment and Study of Anxiety in Philadelphia. "The science simply isn't there at this point."
No useful information
Under certain conditions, it's possible to distinguish a group of individuals with a particular diagnosis from a group of individuals without that diagnosis by showing that, on average, the groups differ in brain activity or brain size, Gillihan explains.
"But generally, there's great variability in the brain measures within groups, such that an individual's diagnostic status tells us almost nothing about what his or her brain will look like," he says. "Knowing a person's brain activity or structure tells us next to nothing about the diagnostic status of that individual."
Therefore, single photon emission computed tomography (SPECT) scans, in the context of a psychiatric evaluation, are not worth what they cost because they don't provide any useful information, says Gillihan.
"It would be a much bigger problem, in terms of patient care, if doctors relied solely on SPECT scans to make psychiatric diagnoses, given the low signal that comes from these scans," he says.
The fact that doctors are instead using them as collateral information in psychiatric assessments, says Gillihan, "should tell us something about the usefulness of these scans, compared to the less expensive and more reliable method of asking patients about their experiences."
"I don't know of many people who think many psych patients can benefit from neuroimaging. We just don't know enough," says Hank Greely, JD, director of the Stanford (CA) Law School's Center for Law and the Biosciences and chair of the Stanford Center for Biomedical Ethics steering committee. "And what we do know can probably be revealed by a structural scan, not a functional one."
For instance, a brain tumor in the prefrontal lobes can be a possible explanation for odd behavior without needing SPECT. "Doing useless things but charging money for it — sometimes big money- — is an ethical problem," he adds. "This is especially true if what you are doing is very expensive, involves a serious condition like autism, and really cannot lead to any generally accepted findings."
Greely says other ethical problems are interventions without clinical value involving radiation exposure to the brain, and incidental findings such as a potentially medically significant aneurysm or tumor.
"I am optimistic that we will be able to use neuroimaging — whether structural or functional and, if functional, whether SPECT, [positron emission tomography], [functional magnetic resonance imaging], or something else — regularly in diagnosis," says Greely. "We just can't now."
Seth J. Gillihan, PhD, Visiting Assistant Professor, Haverford (PA) College. E-mail: firstname.lastname@example.org.
Hank Greely, JD, Director, Center for Law and the Biosciences, Stanford (CA) Law School. Phone: (650) 723-2517. E-mail: email@example.com.
Patients and family may be "easily mesmerized"
It could appear that single photon emission computed tomography (SPECT) scans are offered to psychiatric patients largely for profit, given the cost associated with these scans and the lack of additional information that they provide, says Seth J. Gillihan, PhD, visiting assistant professor at Haverford (PA) College.
"That doesn't mean that clinicians cynically market these scans knowing that they have little value," he adds. "My guess is that many genuinely believe that they are useful."
However, even if the scans provided reliable information that duplicated information obtained through lower-tech options like talking to patients, they likely would not change treatment decisions at all, he adds.
"One potential value in these scans is that they confirm for patients that there is a physical basis for what they're experiencing emotionally," he says. "Many patients find this kind of knowledge comforting. It's just that we don't have to image their brains to know about the physical basis for psychiatric conditions."
Patients or their loved ones who are looking for answers about why they are suffering may be "especially vulnerable" to suggestions that the answers lie in looking at the brain, adds Gillihan.
"It does seem to be true that most of us are easily mesmerized by color images of the brain, and probably put more stock in what the images are telling us than we should," he says.