Expanded summary (6th grade reading level):

Kratom is a plant that some people use as a drug. The main chemical in kratom is called mitragynine. This study looked at how mitragynine affects the brains and behavior of mice. The researchers gave different doses of mitragynine to mice for 28 days. They also gave some mice drugs like morphine and THC (the main chemical in marijuana) to compare the effects.

The researchers found that high doses of mitragynine made the mice more active and interested in sweet rewards. It also made the mice have trouble learning and remembering things. These effects were similar to the effects of morphine and THC. However, low doses of mitragynine did not have these effects. The researchers also found that giving the mice a drug that blocks the cannabinoid (CB1) receptors in the brain could reverse the negative effects of mitragynine, morphine, and THC. This suggests that the CB1 receptors are involved in the way these drugs affect the brain.

This study was done in a lab, using mice as the subjects. The researchers did not study humans directly

Key takeaways:

• High doses of mitragynine, the main chemical in kratom, can cause similar effects in mice as morphine and THC (the main chemical in marijuana)
• These effects include increased activity, increased interest in rewards, and problems with learning and memory
• Low doses of mitragynine did not have these negative effects
• The cannabinoid CB1 receptor in the brain seems to be involved in the way these drugs affect the brain and behavior
• This study was done in mice, not humans

For further reading:

Link: https://www.frontiersin.org/articles/10.3389/fphar.2021.708055/full

Full Citation:

Iman, N.I., Ahmad, N.A.Z., Mohd Yusof, N.A., Talib, U.N., Norazit, A., Kumar, J., Mehat, M.Z., Hassan, Z., Müller, C.P. and Muzaimi, M. (2021). Mitragynine (Kratom)-Induced Cognitive Impairments in Mice Resemble 9-THC and Morphine Effects: Reversal by Cannabinoid CB1 Receptor Antagonism. Frontiers in Pharmacology, 12, p.708055