Why Antidepressants Lack Efficacy in Kids

Although depression is increasingly prevalent in children and teenagers, the most commonly prescribed antidepressants afford limited therapeutic benefit to kids.

In an effort to explain this reduced efficacy, researchers set out to identify the biological mechanisms preventing selective serotonin reuptake inhibitors (SSRIs) from relieving depressive symptoms in children.

SSRIs increase levels of serotonin, a brain chemical that helps regulate mood, by blocking the transporters that clear the chemical from the space around neurons in the brain. The research team theorized that auxiliary transporters unaffected by SSRIs could be partially responsible for decreased serotonin levels in children treated with antidepressants.

The authors discovered an auxiliary “vacuum cleaner for serotonin” that was more active in juvenile mice than in adult ones. Blocking this plasma membrane monoamine transporter triggered effects similar to those produced by antidepressants in juvenile mice, but not in adults.

These findings suggest the weakened response to SSRIs in children and teenagers may result from increased activity of this auxiliary transporter.

The results of this study were presented at the American Society for Pharmacology and Experimental Therapeutics Annual Meeting on March 31, 2015.