Plasticity of the acoustic startle reflex in currently abstinent ecstasy (MDMA) users.

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is neurotoxic upon central serotonin systems in experimental animals and probably also in humans. Serotonin is involved in the habituation, sensitization and prepulse inhibition (PPI) of the startle reflex.

OBJECTIVES

To study the plasticity of startle reflex in currently abstinent MDMA users.

METHODS

Electromyographic responses to acoustic startle stimuli (pulse alone and prepulse-pulse trials) were recorded in 23 currently abstinent ecstasy users and 20 matched control subjects. Depending on the extent of their previous drug use ecstasy users were divided into two groups [life-time dose <90 (n=11) and > or =90 pills (n=12), respectively].

RESULTS

There were no significant differences in habituation, sensitization or PPI of the startle reflex between the entire group of ecstasy users and controls. However, sensitization of the startle reflex was stronger in the > or =90 compared with either the <90 MDMA pills or the control group. Correlations between patterns of drug use and startle parameters did not reach the level of significance, although users with a younger age at the onset of MDMA (and other drug) use tended to present with higher sensitization of the startle reflex.

CONCLUSIONS

Heavy users of MDMA (and other recreational drugs) present with strong sensitization of the startle reflex. Nevertheless, it is unclear whether this finding is secondary to the use of MDMA and its well-recognized neurotoxic potential. Alternatively, strong sensitization might reflect a pre-existing trait predisposing to drug use. A clearer picture of the impact of ecstasy on startle plasticity may be obtained from longitudinal investigations.