Thus , the current state of research does not allow for the conclusion that long-term use of MDMA affects decision-making behavior in general .
Different cognitive impairments have been reported as a result of long-term MDMA/ecstasy use .
Increased impulsivity and altered decision-making have been shown to be associated with the development and maintenance of addictive disorders pointing toward the necessity to underst and a potential impairment of decision-making due to MDMA use .
Thus , assessing the long-term effects of MDMA is crucial in order to evaluate its controversially discussed therapeutic use .
The aim of this systematic review was to summarize the scientific literature on potential effects of chronic MDMA use on higher order decision-making processes in humans .
Low-Serotonin Levels Increase Delayed Reward Discounting in Humans
Previous animal experiments have shown that serotonin is involved in the control of impulsive choice , as characterized by high preference for small immediate rewards over larger delayed rewards . Previous human studies under serotonin manipulation , however , have been either inconclusive on the effect on impulsivity or have shown an effect in the speed of action – reward learning or the optimality of action choice . Here , we manipulated central serotonergic levels of healthy volunteers by dietary tryptophan depletion and loading . Subjects performed a “ dynamic ” delayed reward choice task that required a continuous up date of the reward value estimates to maximize total gain . By using a computational model of delayed reward choice learning , we estimated the parameters governing the subjects ' reward choices in  low- , normal , and high-serotonin conditions . We found an increase of proportion in small reward choices , together with an increase in the rate of discounting of delayed rewards in the low-serotonin condition compared with the control and high-serotonin conditions . There were no significant differences between conditions in the speed of learning of the estimated delayed reward values or in the variability of reward choice . Therefore , in line with previous animal experiments , our results show that low-serotonin levels steepen delayed reward discounting in humans . The combined results of our previous and current studies suggest that serotonin may adjust the rate of delayed reward discounting via the modulation of specific loops in parallel corticobasal ganglia circuits
Thus , the current state of research does not allow for the conclusion that long-term use of MDMA affects decision-making behavior in general .
Different cognitive impairments have been reported as a result of long-term MDMA/ecstasy use .
Increased impulsivity and altered decision-making have been shown to be associated with the development and maintenance of addictive disorders pointing toward the necessity to underst and a potential impairment of decision-making due to MDMA use .
Thus , assessing the long-term effects of MDMA is crucial in order to evaluate its controversially discussed therapeutic use .
The aim of this systematic review was to summarize the scientific literature on potential effects of chronic MDMA use on higher order decision-making processes in humans .