Ketamine-Associated Brain Changes: A Review of the Neuroimaging Literature

This review (2018) examines the neural correlates of ketamine-associated brain changes in patients with depression. Although ketamine affects different areas of the brain in various ways, its most notable effects were found in the subgenual anterior cingulate cortex, posterior cingulate cortex, prefrontal cortex, and hippocampus. Ketamine affects emotional blunting, which may be associated with reduced limbic responses to emotional stimuli, and increase neural activity in reward processing. It also reduces brain activation in regions, such as the Default Mode Network (DMN), associated with self-monitoring, which may be linked to its dissociative effects.

Abstract

“Major depressive disorder (MDD) is one of the most prevalent conditions in psychiatry. Patients who do not respond to traditional monoaminergic antidepressant treatments have an especially difficult-to-treat type of MDD termed treatment-resistant depression. Interestingly, subanesthetic doses of ketamine—a glutamatergic modulator—have shown great promise for rapidly treating patients with the most severe forms of depression. As such, ketamine represents a promising probe for understanding the pathophysiology of depression and treatment response. Through neuroimaging, ketamine’s mechanism may be elucidated in humans. Here, we review 47 articles of ketamine’s effects as outlined by neuroimaging studies. Taken together, some important brain areas emerge, especially the subgenual anterior cingulate cortex. Furthermore, ketamine may decrease the ability to self-monitor, increase emotional blunting, and increase activity in reward processing. However, further studies are necessary to elucidate ketamine’s mechanism of antidepressant action.”

Authors: Dawn F. Ionescu, Julia M. Felicione, Aishwarya Gosai, Cristina Cusin, Philip Shin, Benjamin G. Shapero & Thilo Deckersbach