Table 2.

Summary of MDMA and dexamphetamine effects on primary and secondary driving parameters (improvement, no effect, or impairment) as well as subjective measures of arousal and sleep, alone, and in combination with alcohol

	MDMA–alcohol study			Dexamphetamine–alcohol study
	(Veldstra et al. 2012)			(Simons et al. 2012)
	MDMA	Alcohol	MDMA + alcohol	Dexamphetamine	Alcohol	Dexamphetamine + alcohol
Road tracking	Decrease SDLP^a	Increase SDLP^b	Increase SDLP^c	No effects^a	Increased SDLP^b	Increased SDLP^c
Road tracking	Decrease SDLP^a	Increase SDLP^b	Relevance of impairment undecided (95 % CI drug effect includes BAC 0.5 mg/mL as well as 0)^c	No effects^a	Increased SDLP^b	Relevance of impairment undecided (95 % CI drug effect includes BAC 0.8 mg/mL as well as 0)^c
Car following	No effect^a	No effect^a	No effect^a	No effect^a	No effect^a	No effect^a
Risk taking	No effect^a	No effect^a	No effect^a	No effect^a	Shorter gap acceptance; increased red light crossings and number of crashes^b	Shorter gap acceptance; increased red light crossings and number of crashes^c
Risk taking	No effect^a	No effect^a	No effect^a	No effect^a		Relevance of impairment undecided (95 % CI drug effect includes BAC 0.8 mg/mL as well as 0)^c
Laboratory measures of skills related to driving	Not assessed	Not assessed	Not assessed	No effect^a	Impairment of attention, tracking, and RT^b	Impairment of attention, tracking, and RT^b
Subjective measures	Decreased sleepiness^a	Increased sleepiness^b	Increased sleepiness^b	Decreased sleepiness^a	No effect^a	Decreased sleepiness^a

RT reaction time

^aNeutral effects or “stimulating effects”

^b“Impairing” effects

^cImpairments associated with a wide 95 % CI, which indicate a large variety in response; some subjects are as impaired as under alcohol, and others perform as under placebo