The reasons behind why it often takes people several weeks to feel the effect of newly prescribed antidepressants remains somewhat of a mystery – and likely, a frustration to both patients and physicians. How an antidepressant works on the biochemistry and behavior in mice lets researchers tease out the relative influence of two brain proteins on the pharmacology of an antidepressant. They found increased nerve-cell generation in the hippocampus and a quicker response to the antidepressant.