Which neurotransmitter is often linked to anxiety, depression, and aggressiveness?

• A. GABA
• B. Norepinephrine
• C. Dopamine
• D. Serotonin

Answer: (D)

Serotonin is the chemical behind mood regulation and emotional control. It helps balance how we feel, think, and act, influencing mood, worry, and impulse control. When serotonin signaling is off, people often experience depressive symptoms and persistent anxiety, and they may also have less control over aggressive impulses. Because of its central role in sustaining stable mood and moderating arousal and aggression, serotonin is the neurotransmitter most commonly linked to anxiety, depression, and aggressiveness. Clinically, treatments that raise serotonin levels, like selective serotonin reuptake inhibitors, are commonly effective for depression and anxiety, which reinforces how important serotonin is to these states.

Other transmitters contribute too: GABA generally has a calming, inhibitory effect on brain activity and can reduce anxiety when functioning normally; norepinephrine is tied to arousal and stress responses and can heighten anxiety; dopamine relates to reward and motivation and can influence mood and behavior. But the combination of mood disruption, anxiety, and aggression is most consistently associated with serotonin in research and practice.