Neural correlates of rapid antidepressant response to ketamine in bipolar disorder. (18th September 2013)

• Record Type: Journal Article
• Authors: Nugent, Allison C; Diazgranados, Nancy; Carlson, Paul J; Ibrahim, Lobna; Luckenbaugh, David A; Brutsche, Nancy; Herscovitch, Peter; Drevets, Wayne C; Zarate, Carlos A
• Is Part Of: Bipolar disorders. Volume 16:Number 2(2014)
• Page Start: 119
• Page End: 128
• Publication Date: 2013-09-18
• Subjects: Manic-depressive illness -- Periodicals; Depression, Mental -- Periodicals; 616.895
• DOI: 10.1111/bdi.12118
• Languages: English
• ISSNs: 1398-5647

Abstract

<abstract abstract-type="main" id="bdi12118-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bdi12118-sec-0001" sec-type="section"> <title>Objectives</title> <p>Ketamine, an <italic>N</italic>‐methyl <sc>d</sc>‐aspartate (NMDA) antagonist, has rapid antidepressant effects in depressed subjects with bipolar disorder (BD). Evidence supports a role for the glutamatergic system in the pathophysiology of BD. This double‐blind, randomized, cross‐over study sought to determine cerebral metabolic correlates of antidepressant response to ketamine.</p> </sec> <sec id="bdi12118-sec-0002" sec-type="section"> <title>Methods</title> <p>Twenty‐one subjects with BD currently in a depressed state underwent [<sup>18</sup>F]‐fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging after receiving a placebo infusion as well as after receiving a ketamine infusion. Metabolism was compared between ketamine and placebo infusions, and correlated with clinical response. Regional metabolic rate of glucose (rMRGlu) in regions of interest (ROIs) and Montgomery–Åsberg Depression Rating Scale (MADRS) scores were the main outcome measures.</p> </sec> <sec id="bdi12118-sec-0003" sec-type="section"> <title>Results</title> <p>The study found that change in metabolism between sessions was significantly correlated with percentage change in MADRS scores in the right ventral striatum; subjects who showed the greatest improvement had the largest metabolic increase after ketamine infusion compared to placebo. In a voxel‐wise analysis, subjects with BD had significantly lower glucose metabolism in the left hippocampus following the ketamine infusion than following the placebo infusion. In addition, metabolism in the subgenual anterior cingulate cortex (ACC) following the placebo infusion was positively correlated with percentage improvement in MADRS score following the ketamine infusion.</p> </sec> <sec id="bdi12118-sec-0004" sec-type="section"> <title>Conclusions</title> <p>Taken together, the results suggest that higher activity in the subgenual ACC may predict antidepressant response to ketamine. Ketamine administration altered glucose metabolism in areas known to be involved in mood disorders; these alterations may partially underlie ketamine's mechanism of action.</p> </sec> </abstract>