Decreased cerebral blood flow in the limbic and prefrontal cortex using SPECT imaging in a cohort of completed suicides.

ABSTRACT:
Suicide has a high comorbidity with impulsivity and depression, and finding imaging biomarkers indicative of patients at high-risk for suicidal behavior is invaluable to the clinician. Using single-photon emission computed tomography (SPECT) imaging, we have previously reported regional cerebral blood flow (rCBF) decreases in the medial prefrontal cortex, ventral tegmental area, and subgenual cingulate cortex (Brodmann Area 25), a region found to be hypoperfused with treatment-resistant depression. From 2007-2010, we have extended our analysis to include nine additional completed suicides. Twenty-seven healthy, age-gender matched subjects from a previously acquired healthy brain study served as controls to our twenty-one completed suicides. All twenty-one suicides had been previously diagnosed with depression according to DSM-IV criterion. Voxel-by-voxel analyses were performed using statistical parametric mapping (SPM) to compare the differences in 99mTc-HMPAO brain uptake between the groups. Factor analysis of the data identified the top ten regions of hypoperfusion in the suicidal group including the bilateral superior frontal lobes, the right precuneus, the rolandic operculum, postcentral gyrus, left caudate and insular cortex. We also demonstrate more focal decreases in rCBF in the subgenual cingulate cortex (BA 25) in eighteen subjects, supporting our previous hypothesis that hypoperfusion of BA 25 may be a risk factor for suicide in depressed patients. This work suggests that SPECT might be useful in predicting suicidal tendencies in subjects with depression or treatment-resistant depression. Further investigation of this work is necessary to better understand the predictive value of this finding.