Which neurotransmitter systems, besides dopamine, are commonly altered in chronic drug use?

• A. Glutamate and GABA
• B. Acetylcholine and norepinephrine
• C. Only dopamine
• D. Serotonin only

Answer: (A)

During chronic drug use, brain changes extend beyond dopamine to other major neurotransmitter systems, especially the glutamatergic and GABAergic systems. Glutamate drives learning and plasticity in the brain’s reward circuits, so repeated drug exposure can shift how cues and contexts provoke craving, involving glutamatergic projections from the prefrontal cortex to the nucleus accumbens and related pathways. GABA provides inhibition in these circuits, and its adaptations can alter the balance of excitation and inhibition, strengthening maladaptive drug‑seeking behaviors and contributing to lasting changes even after stopping use.

These glutamate and GABA changes help explain why relapse can be triggered by environmental cues and why changes persist beyond initial dopamine-related reward signaling. While acetylcholine, norepinephrine, and serotonin can be involved with certain drugs, the most consistently altered systems across chronic use are glutamate and GABA, making them the best answer.