Short-Term Response is not Predictive of Long-Term Response to Acetylcholinesterase Inhibitors in Old Age Subjects with Alzheimer's Disease: A "Real World" Study

Background: Most of clinical guidelines recommend discontinuing treatment with cholinesterase inhibitors (ChEIs) in patients with Alzheimer’s disease (AD) who do not show an initial response to therapy as evaluated with the Mini-Mental State Examination (MMSE) scale. However, understanding the relationship between the initial response to ChEI treatment and the subsequent course of the disease is extremely important in clinical practice, but evidence is limited, particularly in the old-old population. Objective: We aimed at investigating the relationship between short-term and long-term response to ChEI therapy in old age subjects with AD in a “real life” setting. Methods: This is a retrospective longitudinal study of 628 old age subjects (≥65 years old) with AD and treated with ChEIs over three year follow-up. The sample was divided into “young-old” (≤75 years) and “old-old” (≥76 years) according to age, and as “responder” and “non-responder” according to the initial (i.e., after three months) response to treatment. Cognitive and functional evaluation was performed by means of MMSE and ADL/IADL, respectively. Results: In the long run, subjects considered as non-responders showed a lower rate of cognitive decline as compared with responders, with a mean annual decline at MMSE of 1.0 point versus 1.6 points (p < 0.0001), respectively. Old-old non-responders had a slower rate of cognitive (p < 0.0001) and functional decline (p < 0.0001) as compared with responders after three years of observation. Conclusion: Discontinuing ChEI treatment solely for the absence of an initial response is not appropriate, especially in old-old subjects.