CARDIOVASCULAR AUTONOMIC DYSREGULATION IN USERS OF MDMA (ECSTASY)

The present study examined resting heart rate variability (HRV; an ind ex of parasympathetic tone) and heart rate response to the Valsalva ma neuver (Valsalva ratio; an index of overall autonomic responsiveness) in 12 repeat users of 3,4-methylenedioxymethamphetamine (MDMA-''Ecstas y''), and a matched comparison group of presumed nonusers. HRV and Val salva ratio were smaller in users than in controls. Three out of 12 MD MA users but no controls had Valsalva ratios below 1.50, the cut-off f or autonomic dysfunction. In several users, there was a total absence of post-Valsalva release bradycardia. All MDMA users were polydrug use rs. Parasympathetic cardiovascular tone appears impaired in repeat MDM A users, although the ubiquitous problems in such epidemiologic design s (including lack of testing before the first use of the drug and conf ounding with use of other drugs) preclude definitive causal interpreta tions.