Neuroimaging in Pursuit of Neurobiology: Strengths, Limitations, and the Quest for New Paradigms in Depression and Mood

Abstract

Alterations in regional cerebral blood flow (rCBF) and glucose metabolism (rCMRglc) have been consistently identified in patients with mood and other psychiatric disorders when compared with control subjects without current or past psychopathology. 1. Lesser IM Mena I Boone KB et al. Reduction of cerebral blood flow in older depressed patients. Arch Gen Psychiatry. 1994; 51: 677-686 Google Scholar , 2. Baxter LR Phelps ME Maziotta JC et al. Cerebral metabolic rates for glucose in mood disorders: studies with positron-emission tomography and fluorodeoxyglucose18. Arch Gen Psychiatry. 1989; 42: 441-447 Google Scholar , 3. Bench CJ Frackowiak RSJ Dolan RJ Changes in regional cerebral blood flow on recovery from depression. Psychol Med. 1995; 25: 247-251 Google Scholar , 4. Bonne O Krausz Y Shapira B et al. Increased cerebral blood flow in depressed patients responding to electroconvulsive therapy. J Nucl Med. 1996; 37: 1075-1080 Google Scholar , 5. Buchsbaum M Wu J Siegel B et al. Effect of sertraline on regional metabolic rate in patients with affective disorder. Biol Psychiatry. 1997; 41: 15-22 Google Scholar Techniques such as positron-emission tomography (PET), single photon-emission computed tomography (SPECT), and Xenon133 inhalation have each been utilized to better characterize the physiological correlates of the major psychiatric disorders. 1. Lesser IM Mena I Boone KB et al. Reduction of cerebral blood flow in older depressed patients. Arch Gen Psychiatry. 1994; 51: 677-686 Google Scholar , 2. Baxter LR Phelps ME Maziotta JC et al. Cerebral metabolic rates for glucose in mood disorders: studies with positron-emission tomography and fluorodeoxyglucose18. Arch Gen Psychiatry. 1989; 42: 441-447 Google Scholar , 3. Bench CJ Frackowiak RSJ Dolan RJ Changes in regional cerebral blood flow on recovery from depression. Psychol Med. 1995; 25: 247-251 Google Scholar , 4. Bonne O Krausz Y Shapira B et al. Increased cerebral blood flow in depressed patients responding to electroconvulsive therapy. J Nucl Med. 1996; 37: 1075-1080 Google Scholar , 5. Buchsbaum M Wu J Siegel B et al. Effect of sertraline on regional metabolic rate in patients with affective disorder. Biol Psychiatry. 1997; 41: 15-22 Google Scholar , 6. Drevets WC Geriatric depression: brain imaging correlates and pharmacologic considerations. J Clin Psychiatry. 1994; 55 (98–100): 71-82 Google Scholar , 7. Kennedy SH Javanmard M Vaccarino FJ A review of functional neuroimaging in mood disorders: positron-emission tomography and depression. Can J Psychiatry. 1997; 42: 467-475 Google Scholar These in-vivo central nervous system (CNS) probes were initially used in cross-sectional studies to demonstrate differences in neocortical and subcortical physiological indices between patients with psychiatric illnesses and control subjects. Subsequently, their application in clinical neuroscience has broadened to include the monitoring of physiological change over time and to examine blood flow and metabolism before and after successful treatment of depression. 3. Bench CJ Frackowiak RSJ Dolan RJ Changes in regional cerebral blood flow on recovery from depression. Psychol Med. 1995; 25: 247-251 Google Scholar , 4. Bonne O Krausz Y Shapira B et al. Increased cerebral blood flow in depressed patients responding to electroconvulsive therapy. J Nucl Med. 1996; 37: 1075-1080 Google Scholar , 5. Buchsbaum M Wu J Siegel B et al. Effect of sertraline on regional metabolic rate in patients with affective disorder. Biol Psychiatry. 1997; 41: 15-22 Google Scholar , 6. Drevets WC Geriatric depression: brain imaging correlates and pharmacologic considerations. J Clin Psychiatry. 1994; 55 (98–100): 71-82 Google Scholar , 7. Kennedy SH Javanmard M Vaccarino FJ A review of functional neuroimaging in mood disorders: positron-emission tomography and depression. Can J Psychiatry. 1997; 42: 467-475 Google Scholar Although several important observations have emerged from these early neuroimaging endeavors, discrepancies in the findings from different groups, together with difficulty in replicating certain observations, have limited the definitive conclusions that could be drawn from these data.