Decreased resting state metabolic activity in frontopolar and parietal brain regions is associated with suicide plans in depressed individuals

Suicide plans are a major risk factor for suicide, which is a devastating outcome of depression. While structural and functional brain changes have been demonstrated in relation to suicidal thoughts and behaviour, brain mechanisms underlying suicide plans have not yet been studied. Here, we studied changes in regional cerebral metabolic activity in association with suicide plans in depressed individuals. Using 18FDG-PET, a comparative study of regional cerebral glucose metabolism (rCMRglu) was carried out in depressed individuals with suicidal thoughts and suicide plans, depressed individuals with only suicidal thoughts, depressed individuals without suicide thoughts and plans, and healthy controls. When compared to the other groups, depressed individuals with suicide plans showed relative hypometabolism in the right middle frontal gyrus and the right inferior parietal lobe (Brodmann areas 10 and 39). Suicide plans in depressed individuals appear to be associated with reduced activity in brain areas that are involved in decision-making and choice, more particularly in exploratory behaviour.