Biological researchers have found a link between suicide and

Biological researchers have found a link between suicide and

• A. Low activity levels of serotonin
• B. An elevated number of serotonin receptor sites
• C. High activity levels of dopamine
• D. High levels of 5-hydroxyindoleacetic acid

Answer: (A)

Low serotonin activity is most closely tied to suicidal behavior because serotonin helps regulate mood, impulse control, and inhibition of aggressive or impulsive actions. When serotonin function is reduced, this emotional and behavioral regulation weakens, which research has linked to increased suicidal risk. The finding is often reflected in lower levels of its metabolite, 5-HIAA, in cerebrospinal fluid, signaling less serotonin turnover in the brain. The other options don’t fit as well. Elevated serotonin receptor sites suggest upregulation in response to low serotonin, but the direct and most consistently observed association is reduced serotonin activity itself rather than receptor changes. High dopamine activity isn’t as clearly connected to suicidality in broad research, since dopamine relates more to reward and motivation than to the specific mood/impulse control pattern linked to suicide. High levels of 5-HIAA would indicate increased serotonin breakdown, implying higher, not lower, serotonin activity, which contradicts the established link to suicidality.

Low serotonin activity is most closely tied to suicidal behavior because serotonin helps regulate mood, impulse control, and inhibition of aggressive or impulsive actions. When serotonin function is reduced, this emotional and behavioral regulation weakens, which research has linked to increased suicidal risk. The finding is often reflected in lower levels of its metabolite, 5-HIAA, in cerebrospinal fluid, signaling less serotonin turnover in the brain.

The other options don’t fit as well. Elevated serotonin receptor sites suggest upregulation in response to low serotonin, but the direct and most consistently observed association is reduced serotonin activity itself rather than receptor changes. High dopamine activity isn’t as clearly connected to suicidality in broad research, since dopamine relates more to reward and motivation than to the specific mood/impulse control pattern linked to suicide. High levels of 5-HIAA would indicate increased serotonin breakdown, implying higher, not lower, serotonin activity, which contradicts the established link to suicidality.