Ketamine's Altered States Meta-Analysis The Relationship Between Psychomimetic and Clinical Effects With Focus in Depression

Background: In recent years, there has been a significant focus on exploring the potential therapeutic impact of altered states of consciousness on treatment outcomes for mental illness, with the goal of enhancing therapeutic strategies and patient results. Methods: This meta-analysis was designed to investigate the potential link between the psychomimetic effects of ketamine and clinical outcomes in mental health, which adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: Eleven studies were selected for meta-analysis, and the main result did not find a significant correlation between the psychoactive effects of ketamine and clinical outcomes either in mental illness (n = 11; n's = 27; r = 0.06 [−0.05, 0.17]; P = 0.268) or depression exclusively (n = 10; n's = 25; r = 0.03 [−0.07, 0.13]; P = 0.561). High heterogeneity was found for general analysis (I2 = 80.78). Egger's regression did not indicate publication bias (intercept = 1.57; SE = 1.49, P = 0.30). No significant Kendall's rank correlation coefficient was observed (τ = 0.02, P = 0.88) indicating funnel plot symmetry. The sub-analyses, aimed at minimizing study variability by specifically examining factors such as patient disorders (limited to depression), methods of administration (exclusively intravenous), types of assessment instruments, and the timing of evaluations, also yielded no significant findings. Conclusion: This meta-analysis suggests that the altered states of consciousness experienced during ketamine sessions are not directly linked to clinical outcomes. However, it is important to acknowledge that the limited number of studies and their heterogeneity render this conclusion preliminary, warranting further investigation over time.