Intensity dependence of auditory evoked dipole source activity in polydrug ecstasy users: evidence from an 18 months longitudinal study

Abstract

Numerous animal studies have been able to demonstrate neurotoxic damage to central serotonergic systems after exposure to 3,4-methylenedioxymethamphetamine (MDMA, ecstasy). It has been suggested that a high loudness dependence of auditory evoked potentials (LDAEP) and, particularly, of the tangential N1/P2 source activity is associated with a low functioning of serotonergic activity. Therefore, the LDAEP may be used as a non-invasive indicator for a possible neurotoxic damage caused by the long-term use of ecstasy in recreational users. We recorded auditory evoked potentials (AEP) with a passive listening paradigm in 18 polydrug ecstasy users at baseline (t1) and after 18 months (t2). Several aspects of ecstasy use, such as frequency of use, cumulative lifetime dose or period of abstinence were associated with the LDAEP for several tangential dipoles at both measuring times. However, we failed to demonstrate any significant relationship between drug use reported at follow-up and AEP changes from baseline to follow-up. Despite some incertitude these data suggest, yet do not unambiguously con.rm, the hypothesis that abstinent ecstasy users present with diminished central serotonergic activity. This feature of information processing is potentially related to the neurotoxic potential of ecstasy. However, alternative interpretations of these data refer to possible preexisting traits and the potential impact of other illicit drugs, particularly amphetamine, since ecstasy users typically exhibit polydrug use patterns. Thus, further research with larger sample sizes and prospective study designs are needed to definitively establish a causative link between ecstasy use and neurotoxicity-related dysfunctions in sensory processing.

Determination of the loudness dependence of auditory evoked potentials: single-electrode estimation versus dipole source analysis

“…Guille and colleagues had compared drug effects on both methods (with no significant differences reported) but did not perform a baseline comparison between the single‐electrode method and DSA (Guille et al , ). However, a large number of studies using either the single‐electrode method (e.g., Kawohl et al , , ; O'Neill et al , , ; Roser et al , ); Oliva et al , or DSA (e.g., Juckel et al , ; Daumann et al , ; Juckel et al , ) exists. We therefore suggest to continue with multichannel measurements in the future and to perform both single‐electrode estimations and DSA in order to be able to relate the results to the existing literature.…”

Loudness dependence of auditory evoked potentials (LDAEP) correlates with the availability of dopamine transporters and serotonin transporters in healthy volunteers—a two isotopes SPECT study

“…However, these results could not be duplicated by other research groups (Daumann et al 2006;Guille et al 2008;Juckel et al 2007;O'Neill et al 2008a;Roser et al 2009). According to the review by O'Neill et al (2008a), the LDAEP shows more promise as a potential predictor of antidepressant treatment responses Lee et al 2005;Linka et al 2005;Mulert et al 2007;Pogarell et al 2007a), although the acute depletion studies in humans that provide little evidence of LDAEP is sensitive to the acute changes in 5-HT function (Debener et al 2002;Norra et al 2008;O'Neill et al 2008b).…”

Intensity dependence of auditory P2 in monozygotic twins discordant for Vietnam combat: Associations with posttraumatic stress disorder

“…Abstinent users of "ecstasy" (methylenedioxymethamphetamine), a drug shown to have neurotoxic effects on central serotoninergic systems in animal research, also show increased intensity dependence compared with control subjects [27][28]. An 18-month follow-up study also found that prior ecstasy use was associated with increased intensity dependence [29]. However, changes in ecstasy use at follow-up were not related to changes in intensity dependence, leading the researchers to speculate whether the increased intensity dependence exhibited by ecstasy users represents a preexisting trait or is an irreversible change in 5-HT function.…”