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 (BA 25)), a region found to be hypoperfused with treatment-resistant depression. From 2007 to 2010, we have extended our analysis to include nine additional completed suicides. In all, 27 healthy, age- and gender-matched subjects from a previously acquired healthy brain study served as controls to our 21 completed suicides. All 21 suicides had been previously diagnosed with depression according to Diagnostic and Statistical Manual of Mental Disorder-IV criterion. Voxel-by-voxel analyses were performed using statistical parametric mapping to compare the differences in technetium-99m hexamethylpropylene amine oxime brain uptake between the groups. Factor analysis of the data identified the top 10 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 18 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 risk for suicide completion in subjects with depression or treatment-resistant depression. Further investigation of this work is necessary to better understand the predictive value of this finding.

Figure 1

Three-dimensional (3D) surface images showing global brain single-photon emission computed tomography (SPECT) decreases in suicide subjects versus healthy brain subjects. Cortical surface views show decreased regional cerebral blood flow in suicide subjects at P<1 × 10⁻¹⁰, family-wise error (FWE ). Significant decreases are in blue. No increases were observed.

Figure 2

Three-dimensional (3D) surface images showing regional cerebral blood flow (rCBF) deficits predictive of suicide. Cortical surface views show areas of decreased rCBF, which predict suicide at P<0.05, family-wise error (FWE). Significant decreases are in blue.

Figure 3

Image sections showing regional cerebral blood flow (rCBF) decreases predictive of completing suicide. Transverse, coronal and sagittal sections showing predictive areas of suicide: Transverse 49—postcentral left; 69—right and left frontal areas; 88—frontal inferior right, postcentral right, caudate right, thalamus right, precuneus right; 94—frontal inferior right, postcentral right, caudate right, thalamus right, precuneus right; 97—insular cortex right, caudate right, insular cortex left, precuneus right; 113—insular cortex right, frontal inferior orbital left (Brodmann area (BA) 25). Coronal 36—left and right frontal lobes; 49—frontal superior right, frontal superior left, insular cortex; 56 frontal superior right, frontal superior left, inferior frontal right, frontal inferior orbital left (BA25); 74—insular cortex right, caudate right, insular cortex left; 104—rolandic operculum right, thalamus right, postcentral left, 144—precuneus right. Sagittal 45—rolandic operculum right; 60—frontal cortex right, insular cortex right, frontal inferior cortex right (BA 25); 76—frontal cortex, caudate right, precuneus; 80—frontal cortex, caudate, thalamus right, precuneus; 97—frontal inferior orbital left (BA 25), thalamus; 138—postcentral left.

Figure 4

Three-dimensional (3D) surface images showing global brain single-photon emission computed tomography (SPECT) decreases in suicide cohort versus depressed non-suicidal cohort. Cortical surface views show diffuse regions of decreased regional cerebral blood flow in suicide subjects at P<1 × 10⁻⁵, family-wise error (FWE) in comparison to non-suicidal subjects with matched diagnostic profiles. Significant decreases are in blue. No increases were observed.

Figure 5

Three-dimensional (3D) surface images showing regional cerebral blood flow (rCBF) deficits predictive of suicide completion in suicide cohort versus a depressed non-suicidal clinical population. Cortical surface views showing areas of decreased rCBF predictive of suicide in completers versus depressed non-suicidal subjects with matched diagnostic profiles at P<0.01, without family-wise error (FWE). Significant decreases are in blue.