Which powerful and addictive stimulant produces temporarily increased alertness and euphoria and blocks dopamine reuptake?

• A. Methamphetamine
• B. Nicotine
• C. Cocaine
• D. Ecstasy

Answer: (C)

Blocking dopamine reuptake in the brain’s reward circuits causes a quick, intense surge of dopamine, which leads to temporary increases in alertness and euphoria. Cocaine achieves this by blocking the dopamine transporter, preventing dopamine from being reabsorbed into the neuron and leaving more of it in the synaptic cleft to stimulate receptors. That rapid dopaminergic spike drives the strong reinforcing effects and high addiction potential. Methamphetamine also boosts dopamine, but mainly by increasing release and reversing transporters rather than primarily blocking reuptake; nicotine increases dopamine indirectly through nicotinic receptors rather than blocking reuptake; MDMA mainly increases serotonin with secondary dopaminergic effects, so its primary action isn’t blocking dopamine reuptake.