In a 2013 clinical trial, the widely prescribed antidepressant citalopram (sold under Celexa and other trade names) was found to reduce the agitation that is often experienced by people with Alzheimer's disease. The drug was not effective for all patients, however, and some trial participants experienced negative side effects when taking citalopram, including cognitive decline and heart arrhythmias.

Researchers have now analyzed the results of the 2013 trial more deeply and determined that citalopram is most likely to benefit those participants in the trial  who had relatively less agitation and  cognitive impairment than other participants. Citalopram appeared less likely to benefit the patients with more moderate to severe cognitive impairment and more severe agitation. Moreover, the study showed that patients with severe agitation or cognitive impairment, and those living in nursing homes, may actually have done worse with citalopram than placebo.

Some Alzheimer's patients are likely to benefit from antidepressant treatment to reduce agitation. Tweet >

The new analysis was reported January 15 in the American Journal of Psychiatry. The research team was led by Lon S. Schneider, M.D., at the University of Southern California, and included NARSAD 1997 Independent Investigator and 1987 Young Investigator Davangere P. Devanand, M.D., and 1996 Young Investigator Gregory Pelton, M.D., who are both at Columbia University Medical Center.

The Citalopram for Agitation in Alzheimer Disease trial involved 186 patients with Alzheimer’s disease showing various  degrees of agitated, disruptive, or aggressive clinical behaviors. The results, taken as a whole, suggested that the antidepressant citalopram was more effective than a placebo in reducing agitation and aggression in patients. But the drug was not without safety concerns. The current study sought to discover the patients or groups within the study who were most likely to benefit.

The researchers found no single factor that could be used to predict how an individual would respond to citalopram, but certain combinations of factors were associated with better outcomes.

Patients who responded best to citalopram tended to be those with moderate agitation and low cognitive impairment. They were also more likely to live at home than in a long-term care facility and to be between the ages of 76 and 82 (trial participants ranged from 47 to 92 years old). Those with more severe agitation and greater cognitive impairment and often resident in nursing homes, in contrast, were at greater risk for adverse responses to the drug. In this group, the researchers found, citalopram may actually have been dangerous; results with placebo were clearly better.

Takeaway: A new analysis of clinical trial data finds Alzheimer's patients with mild cognitive impairment and moderate agitation are most likely to benefit from treatment with the antidepressant citalopram.