Psychiatry is rooted in the brain. All that we think or feel and all that goes wrong in the ways that we think and feel occurs in the brain. It has become increasingly unlikely that diagnoses as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM) represent distinct neurophysiological entities. They will likely prove to represent groups of neurophysiological processes. Individual symptoms likely represent abnormal neurophysiological processes which span across diagnoses (e.g., impulsivity is a key component of the diagnosis of Impulse Control Disorder NOS, Attention-Deficit Hyperactivity Disorder {ADHD}, Bipolar mania, and certain personality disorders; but is also seen following frontal lobe injury, as in mild traumatic brain injury {TBI}, and in Frontal Temporal Dementia). So, it only follows that functional neuroimaging will fail to reveal a singular neurophysiological process corresponding in a one-to-one fashion with a DSM diagnosis. There is substantial evidence that there are multiple neurophysiological causes and imaging findings associated with conditions such as depression1-5, bipolar disorder6-9, ADHD10-23, autism24-28, and schizophrenia29,30. Yet, a brain-based understanding of psychiatric disorders remains an alien concept, scorned by much of the psychiatric community.

Neuroimaging is the way in which medical science looks at the brain. Anatomical imaging such as CT or MRI, allows us to look at the structure of the brain. These modalities can show tumors, bleeding, fractures, and degenerative changes in the late stage of dementia. But much as looking at a circuit board will not tell you if a computer will work, anatomical imaging (CT or MRI) contribute little to knowing if the brain is working properly. Functional brain imaging, such as Single Photon Computed Tomography (SPECT), Positron Emission Tomography (PET), and functional Magnetic Resonance Imaging (fMRI), allow you to examine brain function. These forms of imaging demonstrate how many parts of the brain are functioning, including critical areas like the temporal lobes and deep nuclei. Other modalities which are described as “scans”, such as qEEG, can only provide information about superficial areas of the cortex and provide no information about critical deep structures, such as the cingulate gyri, caudate nuclei, medial temporal lobes, and striatum.

In 2011, Dr. Henderson co-chaired a symposium at the American Psychiatric Association (APA) meeting entitled, The Pros and Cons of SPECT Brain Imaging in Psychiatry31.  This was the first time in almost 10 years that SPECT brain imaging had been presented at the APA, reflecting a long-standing dismissal of SPECT by Psychiatry. At the symposium, the safety and potential clinical value of SPECT to address complex psychiatric diagnoses was presented.  Dr. Michael Devous spoke concerning the technical aspects of SPECT and emphasized its value in evaluating the base of the brain because SPECT is free of artifact compared to CT or MRI. He also emphasized the value of SPECT in the evaluation of dementia wherein his own research has shown it to have a sensitivity of 89% and a specificity of 97%32. While critical of using SPECT for psychiatric illnesses, Dr. Devous clearly articulated the established indications of SPECT brain imaging, including stroke, seizures, traumatic brain injury (TBI – see link), and toxic brain injury. Dr. Daniel Amen spoke about psychiatric applications of SPECT imaging, emphasizing that much of the time, SPECT is being used to ferret out undiagnosed TBI, toxic brain injury, partial complex seizures, and other neurological disorders that can masquerade as psychiatric disorders. He reviewed the relevant chapters of Morton’s textbook entitled Diagnostic Nuclear Medicine33 and Kaplan and Saddock’s Comprehensive Textbook of Psychiatry34, both of which state SPECT has considerable value in psychiatric indications. Dr. Amen discussed a recent study he and colleagues had completed wherein the charts of approximately 200 patients were assessed in a blind review by independent psychiatrists and a diagnosis was made. When the scan data was added to the clinical information, 75% of the cases had a change in diagnosis and indicated treatment.

In this debate, Dr. Henderson presented a scientific review of SPECT brain imaging. He began by emphasizing that SPECT scans are a form of medical test and, like all medical tests, has false negatives and false positives. Medicine accepts most other tests as “accurate”, despite the potential for false positives and false negatives; yet Psychiatry seems to hold neuroimaging to some higher standard. He further illustrated that imaging findings in radiology frequently yield multiple possible diagnoses. In Psychiatry, the situation is even more complicated, because patients often have multiple psychiatric diagnoses. This is further confounded by the fact that more than one kind of brain process can create a single psychiatric symptom – be it depression, anxiety, or inattention.

Dr. Henderson then explained the neurobiological underpinnings that allow us to visualize brain function with neuroimaging. He went on to explain the physics of PET, fMRI, and SPECT, emphasizing the strengths and weaknesses of each modality. In explaining SPECT, he underscored that SPECT and fMRI both looked at changes in perfusion as a way to assess brain function. Dr. Henderson moved on to discuss radiation safety. He illustrated the low level of radiation associated with a SPECT scan (about 0.7 rems) compared to other radiological studies and normal background radiation. He then numerous numerous large scale studies with over 100,000 subjects (mostly children) exposed to radiation doses 2-20 times higher than that received in a SPECT brain scan. Despite long-term follow-up for as much as 20 years, there was no long-term increased risk of cancer35.

Dr. Henderson pointed out the flaws in the APA position paper posted on their website in 2005, including the expectation of that psychiatric diagnoses occur in isolation – without comorbidity, the confusion between SPECT brain imaging providing supportive evidence for a diagnosis as opposed to “diagnosing” a psychiatric condition, and the expectation of a diagnostic fingerprint for each psychiatric condition. Moreover, he pointed out how the APA Position Paper confused the physics of SPECT and PET, exaggerated the risk of the associated radiation, and denied the existence of well-established normative databases. Of note, this position paper by the APA was withdrawn several years ago.

Dr. Henderson then reviewed key research studies demonstrating the efficacy of SPECT brain imaging in detecting TBI36-44, dementia45-48, obsessive-compulsive disorder49-54 (OCD), and ADHD10-23. He emphasized that TBI can often produce psychiatric symptoms. He emphasized that numerous SPECT studies and numerous fMRI studies of ADHD found identical results. He provided the audience with numerous research studies illustrating the same result – frontal cortex and orbitofrontal cortex perfusion decreases during concentration tasks in patients with ADHD (reviewed in reference 23). He provided two cases examples illustrating how SPECT brain imaging findings supported or mitigated against the diagnosis of ADHD.

Dr. Henderson built similar cases for bipolar disorder6-9 and for OCD49-54, demonstrating the SPECT research findings correlated with fMRI and PET findings leading to neurobiological processes which distinguish and identify ADHD, bipolar disorder, and OCD. Throughout, he illustrated with case examples of how SPECT brain imaging helped correctly identify the neurobiological processes in a patient and changed his/her treatment with markedly improved results.

Neuroimaging, including SPECT brain imaging, is a tool. It does not replace a careful psychiatric evaluation. Neuroimaging augments the evaluation. Neuroimaging shows us what the patient cannot tell us themselves about the brain trauma they did not think was important, the toxin exposure they may or may not know about, the brain infections they do not know they have, the disorder they have always been told is ADHD but is not, and the partial complex seizure disorder that leads them to behave in a bizarre manner at times.


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