A Curious Consensus: "Brain Scans Prove Disease"?

Article excerpt

Presumably in recognition of the fact that there is no chemical test that can be used to diagnose any of the alleged mental illnesses, journalists and medical opinion leaders have proclaimed that brain scans-particularly, functional imaging studies-can be used to confirm the presence of psychiatric disease. Although the scientific record contradicts these assertions, the news media have ignored a critical evaluation of what, exactly, the new technologies purport to explain. The article that follows presents a critical analysis of the theoretical, practical, and philosophical limitations of the functional neuroimaging modalities (fMRI, PET, SPECT), and why these methods are not used outside of the research setting in the clinical practice of psychiatry today.

Keywords: neuroimaging; functional MRI; PET; neurovascular coupling

Recently, a series of physicians have appeared on national news programs, reassuring the public that psychiatric disorders have been confirmed as "real" diseases of the brain. Perhaps the context of these announcements-a heated exchange between two Hollywood celebrities who have clashed over the medicalization and treatment of postpartum depression-has prevented the media from noticing serious inaccuracies in the recorded testimony of their selected discussants:

When you don't have enough neurotransmitters firing, making the connections, your brain doesn't act like it should. And you can see what a normal brain should look like. That is an objective measure. (Doss, 2005)

Dr. Sanjay Gupta

neurosurgeon/CNN senior medical correspondent

. . . we can see differences between brain images of someone who is depressed and someone who is not depressed. And if we give medications, the brain of the depressed person goes back to looking like a person not depressed. (Doss, 2005)

Dr. Nada Stotland

psychiatrist/secretary, American Psychiatric Association

As none of the featured authorities has clarified the essential distinction between anatomic and functional studies of the human brain, a corrective analysis is necessary and overdue.

DIFFERENCE BETWEEN ANATOMIC AND PHYSIOLOGICAL STUDIES OF THE BRAIN

Anatomic studies depend upon technologies such as computed tomography (CT) and magnetic resonance imaging (MRI) to capture static images of the brain. Because these techniques have been well replicated and validated, they are routinely used by physicians to identify somatic abnormalities, such as tumors, abscesses, or vascular malformations. Despite attempts to the contrary, however, more than 50 years of research have failed to confirm radiographie evidence linking any psychiatric condition to a structural defect within the brain (Dougherty, Rauch, & Rosenbaum, 2004; Hales, Yudofsky, & Talbott, 1999; U.S. Department of Health and Human Services, 1999).

Functional studies, on the other hand, depend upon technologies such as functional MRI (fMRI) and positron emission tomography (PET). These methodologies employ strong magnetic fields or radioactive isotopes, respectively, for the purpose of evaluating brain processes when a person is at rest or engaged in specific activity. Intra- and interindividual investigations of this kind seek to identify the underlying substrates of the nervous system that are presumed to be uniquely involved in certain mental and psychological phenomena (e.g., brain regions that are active or silent during the processes of remembering, learning, perceiving, emoting, intending).

Referring to the images on a functional brain scan in the course of a recent television broadcast, Dr. Sanjay Gupta repeatedly avowed that the new technologies display a visual record of brain activity:

An ADHD brain is on the left side there. You can see, it's mainly on the right side of the brain that things are activating. They should be activating all over and on the left side as well. You see a non-ADHD brain, again, it's different than the ADHD brain. …