Got this from Wikipedia, and probably explains my symptomatic improvenents

Dopamine Reuptake Inhibitors (DARI), Dopamine Uptake Inhibitors, Dopamine Transporter Inhibitors are compounds that inhibit the reuptake of extracellular dopamine back into the presynaptic cell by blocking the cell membrane-spanning dopamine transporter.[citation needed] This usually results in an elevated extracellular dopamine level.