Serotonin imbalances are associated with which conditions?

• A. Depression and OCD
• B. Parkinson's disease
• C. GABA-related disorders
• D. Schizophrenia

Answer: (C)

Serotonin helps regulate mood, emotion, and some aspects of repetitive thinking and impulse control. When serotonin signaling is imbalanced, mood disturbances and obsessive-compulsive patterns tend to arise, which is why depression and OCD are the conditions most closely linked to serotonin dysregulation. Clinically, medications that increase serotonin availability in the brain (SSRIs) are frontline treatments for both major depressive disorder and OCD, reinforcing this connection.

Parkinson's disease centers on dopamine depletion in motor pathways, with serotonin playing a modulatory but not defining role. GABA-related disorders involve the primary inhibitory neurotransmitter GABA, not serotonin, even though serotonin can influence GABA systems. Schizophrenia involves multiple neurotransmitter systems, especially dopamine and glutamate, with serotonin receptors implicated in some treatments but not the core driver of the disorder. The strongest and most direct associations for serotonin imbalance are with depression and OCD.