MDMA and memory, addiction, and depression: dose-effect analysis
Anagnostaras, S. G., Kim, J. L., Pantoni, M. M., Van Alstyne, K. R.
This rodent study (2022) assessed the effects of varying doses of MDMA (0.01 to 10mg/kg) on a number of fear conditioning variables. High doses of MDMA (≥ 3mg/kg) produced amnesia of fear conditioning memory, some evidence of addictive potential, and antidepressant effects, while low doses of MDMA (≤ 1mg/kg) had no effect on these behaviours. These findings suggest that the therapeutic use of MDMA below 3mg/kg is less likely to produce significant adverse cognitive effects.
Abstract
Rationale: ±3,4-Methylenedioxymethamphetamine (MDMA) is a recreational drug that shows substantial promise as a psychotherapeutic agent. Still, there is some concern regarding its behavioural toxicity, and its dose-effect relationship is poorly understood. We previously explored the role of dose in the cognitive effects of MDMA in a systematic review of existing literature and found no evidence in animals that MDMA impairs memory at low doses (< 3 mg/kg) but mixed results at high doses (≥ 3 mg/kg). Since this review is comprised mostly of single-dose studies and an assortment of methodologies, an empirical dose-ranging study on this topic is warranted.Objectives: The current study aims to evaluate the conclusion from our systematic review that 3 mg/kg may be the threshold for MDMA-induced amnesia and to further understand the dose-effect relationship of MDMA on behavioural assays of memory, addiction, and depression.Methods: We systematically examined the effects of 0.01 to 10 mg/kg MDMA on Pavlovian fear conditioning; behavioural sensitization conditioned place preference and conditioned responding, and the Porsolt forced swim test in mice.Results: High doses of MDMA (≥ 3 mg/kg) produced amnesia of fear conditioning memory, some evidence of addictive potential, and antidepressant effects, while low doses of MDMA (≤ 1 mg/kg) had no effect on these behaviours.Conclusions: The present dose-ranging study provides further evidence that 3 mg/kg is the threshold for MDMA-induced amnesia. These findings, in addition to our systematic review, demonstrate that careful selection of MDMA doses is critical. High doses (≥ 3 mg/kg) should likely be avoided due to evidence that they can produce amnesia and addiction. Conversely, there is little evidence to suggest that low doses, which are usually administered in clinical studies (approximately 1-2 mg/kg), will lead to these same adverse effects. Ultra-low doses (< 1 mg/kg) are likely even safer and should be investigated for therapeutic effects in future studies.