How do SSRIs differ from SNRIs in mechanism and preferred use?

• A. SSRI s primarily block serotonin reuptake; SNRI s block both serotonin and norepinephrine reuptake and may be effective for neuropathic pain.
• B. SSRI s block norepinephrine reuptake; SNRIs block dopamine reuptake; SSRIs are used for mood only.
• C. SSRI s increase serotonin and SNRIs decrease serotonin.
• D. They have identical mechanisms and uses.

Answer: (A)

The key idea is how these antidepressants affect two brain chemicals: serotonin and norepinephrine. SSRIs selectively block the serotonin transporter, so they raise serotonin levels in the synapse and mainly help mood and anxiety. SNRIs block both serotonin and norepinephrine transporters, increasing both neurotransmitters. The extra norepinephrine boost can enhance mood further and, importantly, help with pain signaling, making SNRIs especially useful for neuropathic or painful depression. That’s why this option correctly describes the mechanism and a meaningful clinical use. The other statements misstate what is blocked or imply identical actions, which isn’t the case.