Pre-treatment functional connectivity of the cingulate cortex predicts anti-suicidal effects of serial ketamine infusions

Abstract

Background: Although ketamine can rapidly decrease suicidal ideation (SI), its neurobiological mechanism of action remains unclear. Several areas of the cingulate cortex have been implicated in SI; therefore, we aimed to explore the neural correlates of the anti-suicidal effect of ketamine with cingulate cortex functional connectivity (FC) in depression.Methods: Forty patients with unipolar or bipolar depression with SI underwent six infusions of ketamine over two weeks. Clinical symptoms and resting-state functional magnetic resonance imaging data were obtained at baseline and on day 13.Remitters were defined as those with complete remission of SI at day 13. Four pairs of cingulate cortex sub-regions were selected: the subgenual anterior cingulate cortex (sgACC), pregenual anterior cingulate cortex (pgACC), anterior mid-cingulate cortex (aMCC), and posterior mid-cingulate cortex (pMCC) and whole-brain FC for each seed region was calculated.Results: Compared with non-remitters, remitters exhibited increased FC of the right pgACC-left middle occipital gyrus and right aMCC-bilateral postcentral gyrus at baseline. A high area under the curve (0.91) indicated good accuracy of the combination of the above between-group differential FCs as a predictor of anti-suicidal effect. Moreover, the change of SI after ketamine infusion was positively correlated with altered right pgACC-left middle occipital gyrus FC in remitters (r = 0.66, p = 0.001). Conclusions:Our findings suggest that the FC of some cingulate cortex sub-regions