Two optical isomers of MDA exist. These are mirror image versions of the molecule. One version (the S-MDA) is more potent than the other (R-MDA), and possesses more psychoactive stimulant properties, similar to MDMA. Shulgin describes the effects of this version as ‘more peaceful and MDMA-like’ at lower doses. Generally, MDA seems to be longer lasting than MDMA. MDA acts on three transporter molecules in the brain, SERT, NET and DAT that cause an increase in the serotonin, norepinephrine (noradrenaline) and dopamine neurotransmitters, respectively.