AI Article Synopsis

  • Subanesthetic doses of ketamine can rapidly alleviate symptoms of treatment-resistant depression but may also cause temporary psychotomimetic effects, including an altered sense of self.
  • A study using MRI scans on 35 healthy male participants found a negative correlation between cortical thickness in the posterior cingulate cortex (PCC) and scores of disembodiment, suggesting that thinner PCC may relate to a stronger altered self-experience after ketamine use.
  • The findings emphasize the PCC's role in developing an altered sense of self under ketamine, paralleling effects observed with other antidepressants that have psychotomimetic properties.

Article Abstract

Subanesthetic doses of ketamine induce an antidepressant effect within hours in individuals with treatment-resistant depression while it furthermore induces immediate but transient psychotomimetic effects. Among these psychotomimetic effects, an altered sense of self has specifically been associated with the antidepressant response to ketamine as well as psychedelics. However, there is plenty of variation in the extent of the drug-induced altered sense of self experience that might be explained by differences in basal morphological characteristics, such as cortical thickness. Regions that have been previously associated with a psychedelics-induced sense of self and with ketamine's mechanism of action, are the posterior cingulate cortex (PCC) and the pregenual anterior cingulate cortex (pgACC). In this randomized, placebo-controlled, double-blind cross-over magnetic resonance imaging study, thirty-five healthy male participants (mean age ± standard deviation (SD) = 25.1 ± 4.2 years) were scanned at 7 T. We investigated whether the cortical thickness of two DMN regions, the PCC and the pgACC, are associated with disembodiment and experience of unity scores, which were used to index the ketamine-induced altered sense of self. We observed a negative correlation between the PCC cortical thickness and the disembodiment scores (R = -0.54, p < 0.001). In contrast, no significant association was found between the pgACC cortical thickness and the ketamine-induced altered sense of self. In the context of the existing literature, our findings highlight the importance of the PCC as a structure involved in the mechanism of ketamine-induced altered sense of self that seems to be shared with different antidepressant agents with psychotomimetic effects operating on different classes of transmitter systems.

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Source
http://dx.doi.org/10.1016/j.jpsychires.2024.02.019DOI Listing

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