Kratom (<i>Mitragyna speciosa</i>) Use and Mental Health: A Systematic Review and Multilevel Meta-Analysis

Abstract

&lt;b&gt;&lt;i&gt;Introduction:&lt;/i&gt;&lt;/b&gt; Kratom (&lt;i&gt;Mitragyna speciosa&lt;/i&gt;) is a medicinal tree native to Southeast Asia. The present multilevel meta-analysis describes the association between kratom use and the positive and negative indicators of mental health. &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; A total of thirty-six articles were included in the meta-analysis to examine the associations, using a random-effects model. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; The pooled effect size showed a very small positive association between kratom use and negative indicators of mental health {&lt;i&gt;r&lt;/i&gt; = 0.092, 95% confidence interval (CI) = [0.020, 0.164], &lt;i&gt;p&lt;/i&gt; &amp;lt; 0.05}, while no significant association was found with positive indicators of mental health (&lt;i&gt;r&lt;/i&gt; = −0.031, 95% CI = [−0.149, 0.087], &lt;i&gt;p&lt;/i&gt; &amp;gt; 0.05). Pooled effect sizes of specific mental health outcomes indicated that kratom use showed only a small positive correlation with externalizing disorders (&lt;i&gt;r&lt;/i&gt; = 0.201, 95% CI = [0.107, 0.300], &lt;i&gt;p&lt;/i&gt; &amp;lt; 0.001). No significant association was found between kratom use and quality of life (&lt;i&gt;r&lt;/i&gt; = 0.069, 95% CI = [−0.104, 0.242], &lt;i&gt;p&lt;/i&gt; &amp;gt; 0.05) and internalizing disorders (&lt;i&gt;r&lt;/i&gt; = −0.001, 95% CI = [−0.115, 0.095], &lt;i&gt;p&lt;/i&gt; &amp;gt; 0.05). Multilevel moderator analysis showed that the pooled effect size of the association between kratom use and substance use disorder was stronger in Malaysia (&lt;i&gt;r&lt;/i&gt; = 0.347, 95% CI = [0.209, 0.516], &lt;i&gt;p&lt;/i&gt; &amp;lt; 0.001), and with the mean age (β1 = −0.035, 95% CI = [−0.055, −0.014], &lt;i&gt;p&lt;/i&gt; = 0.003), and the drug profile of those who were not co-using other drugs (&lt;i&gt;r&lt;/i&gt; = 0.347, 95% CI = [0.209, 0.516], &lt;i&gt;p&lt;/i&gt; &amp;lt; 0.001). &lt;b&gt;&lt;i&gt;Conclusion:&lt;/i&gt;&lt;/b&gt; The meta-analysis supports the kratom instrumentalization concept, in that a positive gain from kratom consumption can be achieved without any significant adverse associations with mental health.