Fenfluramine challenge test as a marker of serotonin activity in patients with Alzheimer's dementia and agitation

Background: Changes in serotonin (5-HT) have been described in both Alzheimer’s disease (AD) and aggressive/agitated behaviors. This paper explores a possible association between 5-HT deficits and agitation in AD, using prolactin response to d,1-fenfluramine administration as a probe for 5-HT activity. Methods: Five AD patients with agitation and 5 without agitation received a 60-mg oral dose of d,1-fenfluramine. Prolactin levels were obtained at baseline, and 2 and 3 hours following administration. Results: Change in prolactin levels from baseline to 3 hours was significantly larger among the agitated than the nonagitated Alzheimer’s patients. Further, there was a positive and significant correlation between change in prolactin levels from baseline and level of agitation. Conclusions: These findings suggest an association between 5-HT responsiveness and agitation in AD.