Central serotonergic hyperresponsivity in late-onset Alzheimer's disease.

The prolactin response to oral d-fenfluramine (30 mg) was measured in nine patients with late-onset Alzheimer's disease and in an elderly comparison group. The serotonin-mediated prolactin response was significantly greater in the patients with Alzheimer's disease than in the comparison group. This finding suggests that central serotonin responsivity is greater in Alzheimer's disease.