Efficacy of SSRIs on cognition of Alzheimer's disease patients treated with cholinesterase inhibitors

Background: This study examines the joint effect on cognition of selective serotonin re-uptake inhibitors (SSRIs) and cholinesterase inhibitors (AChEIs) in depressed patients affected by Alzheimer's disease (AD) living at home. Methods: The study was conducted in two different outpatient neurological clinics. 338 patients with probable AD were treated with ChEis (donepezil, rivastigmine and galantamine) as per the clinician's judgment and were observed for nine months. At study entry, participants underwent a multidimensional assessment evaluating cognitive, functional and psychobehavioral domains. All patients were evaluated at baseline, after one (T I), three (T2) and nine months (T3). Patients were grouped in three different categories (patients not depressed and not treated with SSRIs, patients depressed and treated with SSRIs, and patients depressed but not treated with SSRIs). Results: At baseline 182 were diagnosed as not depressed and not treated with SSRIs, 66 as depressed and treated with SSRIs, and 90 as depressed but not treated with SSRIs. The mean change in MMSE score from baseline to nine months showed that depressed patients not treated worsened in comparison with those not depressed and not treated with SSRIs (mean change -0.8 +/- 2.3 vs 0.04 +/- 2.9; p = 0.02) and patients depressed and treated with SSRI (mean change -0.8 +/- 2.3 vs 0.1 +/- 2.5; p = 0.03). Conclusions: In AD patients treated with AChEIs, SSRIs may exert some degree of protection against the negative effects of depression on cognition.