The current study prospectively investigated the association between decision-making strategy and future first ecstasy use. We hypothesized that a risky decision-making strategy on a gambling task would predict future first ecstasy use. In our study population, only in female participants was a relationship found between decision-making strategy and future ecstasy use: Less advantageous deck choices on a gambling task resulted in a higher likelihood of future first ecstasy use. In addition, decision-making reaction time differed significantly between the total group of persistent ecstasy-naives and the total group of future ecstasy users: Future ecstasy users did not prolong their reaction times after punishments, whereas persistent ecstasy-naives did.
A possible explanation for the finding that decision-making strategy only was predictive for future ecstasy use in women and not in men might be sought in differences in working memory capacity. Some studies postulate a role for working memory in decision making (Bechara and Martin 2004
; Pecchinenda et al. 2006
), and therefore, it could be theorized that the disadvantageous responses in female subjects of our study sample are due to a decreased working memory. At first sight, there are indications that this is true because in our previous study in the same cohort, female future ecstasy users showed lower scores on working memory tasks than male future ecstasy users (Schilt et al. 2007
). However, after correction for DART-IQ and substance use, differences turned out to be non-significant (p
0.17). Consequently, it seems unjustified to ascribe the differences in decision-making performance between male and female future ecstasy users to differences in working memory.
Possibly, initiation of ecstasy use in men is influenced by other factors than in women. In men, external factors like peer influence or availability of opportunities may play a greater role in the initiation of ecstasy use than in women (Van Etten et al. 1999
), while in women, the start of using ecstasy might be regulated by more internal factors, like personality characteristics or decision-making strategies. In The Netherlands, the percentage of the population (age 15–64) that ever used ecstasy was higher in men than in women (3.7% versus 2.1% in 2001 and 6.6% versus 1.2% in 2005; Drugs Informatie en Monitoring Systeem 2006
), suggesting that for men, ecstasy use is a less unusual thing to do than for women. Women might need to show more deviant behavior to take the first step to ecstasy use.
The finding that future ecstasy users did not prolong their reaction time after punishment may imply higher impulsivity and/or lower punishment sensitivity. Higher impulsivity was also put forward by Goudriaan et al. (2006
) as a possible explanation for a lack of difference in reaction time after rewards or after punishments in alcohol-dependents (Goudriaan et al. 2006
). However, in our study population, future ecstasy users did not report higher impulsivity on a self-report impulsiveness scale (de Win et al. 2006
). This could be due to the lack of an association between self-reported impulsivity and decision-making scores (data not shown). Other studies also failed to find a significant relationship between self-report impulsivity scales and performance on the Iowa Gambling Task (Franken and Muris 2005
; Goudriaan et al. 2007
; Jollant et al. 2005
). Three other studies, however, did find significant correlations between self-reported impulsivity and performance on the Iowa Gambling Task (Christodoulou et al. 2006
; Franken et al. 2008
; Zermatten et al. 2005
), but in two of these studies, different self-report impulsivity scales were used other than the Barratt Impulsiveness Scale (BIS) used in our study. Possibly, the BIS does not capture the kind of impulsivity that is measured with the Iowa Gambling Task. As stated in “Introduction
”, impulsivity is a complex construct that consists of different dimensions (Evenden 1999
). In the study of Zermatten (2005) for example, it appeared that only “premeditation” (thinking at forehand about a future action), as part of impulsivity, was related to decision making (Zermatten et al. 2005
). Dawe and Loxton (2004
) mentioned in their review an association between decision making and “rash unplanned impulsivity” rather than “reward sensitivity/drive” (Dawe and Loxton 2004
). The fact that we did not find indications for self-reported impulsivity as an explanation for the shorter reaction times after losses in future ecstasy users does not mean that there is no connection between certain aspects of impulsivity and IGT performance. Instruments other than the self-report questionnaires used in the current study are needed to investigate this more thoroughly.
The results of this study possibly reflect lower punishment sensitivity in future ecstasy users. Individuals that start to use ecstasy may be less sensitive to the possible negative consequences of their choice. Although some studies did not find an association between substance misuse and sensitivity to punishment (Jorm et al. 1998
; Leland and Paulus 2005
), other studies showed that poor conditioning to signals for punishment is associated with an increased risk of alcohol abuse. This may be a reflection of a weak behavioral inhibition system (Finn et al. 1994
; Loxton and Dawe 2001
; Loxton et al. 2008
). Subjects with low punishment sensitivity may be more prone to try ecstasy because they do not consider the potential negative consequences of drug use.
Some limitations of this study should be mentioned. An important limitation of this study is the selection of the participants. Subjects were selected on the basis of their self-reported wish to start using ecstasy in the near future. Consequently, our study sample was not representative of the general population, which limits the generalizability of the results. This selection process could explain the small effect sizes and lack of associations between decision-making performance and self-report impulsivity questionnaires. Although the effect size for difference in IGT performance between female ecstasy-naives and female future ecstasy users was moderate (Cohen’s d
0.50), the effect size for dRT between ecstasy-naives and future ecstasy users was rather small (Cohen’s d
0.37). Another limitation is that we do not know if the persistent ecstasy-naive subjects would remain ecstasy-naive after the follow-up period of our study (11–26 months). Therefore, our results only provide information about prediction of ecstasy use in the near future, but not of ecstasy use ever. The current study provides only limited support for the use of neuropsychological decision-making tests in the prediction of initial ecstasy use. In contrast, neuropsychological measures of executive functioning and decision-making strategies appear to be stronger predictors for relapse in substance dependence or addictive behaviors (Bowden-Jones et al. 2005
; Dallery and Raiff 2007
; Goudriaan et al. 2008
; Paulus et al. 2005
). Moreover, neuropsychological tests other than the decision-making test used in our study might capture certain aspects of impulsivity better and subsequently could be superior predictors for future ecstasy use. Perhaps, other factors that we did not include in our study could better predict future ecstasy use. Some studies point at cannabis use as a risk factor for later ecstasy use (de Win et al. 2006
; Martins et al. 2007
; Pedersen and Skrondal 1999
; Zimmermann et al. 2005
). However, in the current study, cannabis and cocaine use did not significantly predict future ecstasy use. Possibly, the use of other drugs is especially predictive for frequent ecstasy use rather than for the first incidence of low-dose ecstasy use (mean ecstasy use at final evaluation was 6.3 pills, SD 12.1, median 2.0).
In summary, in this study, decision-making strategy was predictive for first incidental use of ecstasy in female participants within the 11–26 months following baseline assessment. Furthermore, decision-making reaction time differed between future ecstasy users and persistent ecstasy-naives. However, the clinical relevance is limited because effect sizes were small to moderate only. It is conceivable that decision-making strategy is more important in the continuation of ecstasy use than in the initiation of first low-dose ecstasy use. Therefore, it is important to follow this study cohort and to compare decision-making strategy (before first ecstasy use) in the subjects that become frequent ecstasy users with persistent ecstasy-naives.