Suicidal behaviour: What's the brain up to?

Individuals with suicidal behaviours are increasingly recognized as having impairments in brain metabolism. However, these are not well delineated.

To evaluate regional cerebral glucose metabolism (rCMglu) in subjects with suicidal behaviours and assess differences in rCMglu between depressed and non-depressed suicidal subjects.

Thirty-three subjects with suicidal behaviours were assessed using Columbia Suicide Severity Rating scale (CSSRS) and Beck's Depression Inventory (BDI). Brain metabolism was assessed using [¹⁸F]Fluoro,Deoxy-Glucose Positron Emission Tomography (FDG-PET).

Of 33 subjects, eighteen had depression. FDG-PET findings revealed that in comparison to mean asymptomatic controls, subjects had decreased rCMglu in right inferior frontal, left Broca's, left inferiolateral andsuperiolateral temporal, right inferior parietal and left posterior cingulate cortex. Increased rCMglu was seen in bilateral superior and medial frontal, right inferiolateral and posteriomedial temporal cortex, and midbrain. CSSRS total intensity inversely correlated with rCMglu in medial frontal cortex, left Broca's and superiolateral temporal cortex and directly correlated with rCMglu in right cerebellum. There was no significant difference in rCMglu between depressed and non depressed group.

Significant differences exist in rCMglu of suicidal individuals, chiefly in frontal and temporal regions. Understanding these would help us identify individuals more at risk for suicidal behaviours.