Which of the following is NOT classified as a CNS stimulant?

MDMA, also known as ecstasy, is primarily classified as a hallucinogenic and empathogenic substance rather than a central nervous system (CNS) stimulant, although it does have some stimulating effects. This makes it distinct from the other substances listed, which are all well-known CNS stimulants.

Methamphetamine, cocaine, and amphetamine are all recognized for their ability to increase alertness, attention, and energy levels through stimulating the CNS. Methamphetamine and amphetamine increase the levels of certain neurotransmitters in the brain, leading to heightened focus and activity. Cocaine achieves its stimulant effects by preventing the reuptake of dopamine, a neurotransmitter associated with pleasure and reward, thereby increasing its availability in the synaptic cleft.

MDMA, on the other hand, tends to enhance mood, emotional connectedness, and sensory perception, while having a more limited stimulant effect compared to the others, thus placing it outside the primary category of CNS stimulants. This classification highlights the nuanced differences in how these substances affect the brain and behavior.