Recognition performance differentiates between elderly patients in the long term course of secondary progressive multiple sclerosis and amnestic mild cognitive impairment

Abstract

Background: Cognitive impairment is a common symptom of multiple sclerosis (MS), but little is known about cognitive decline in patients in the long-term course of progressive MS. Because advancing age is the most significant risk factor for Alzheimer’s Disease (AD), AD-related pathology must be considered in elderly patients with MS. Amnestic mild cognitive impairment (aMCI) represents the prodromal phase of AD with subjects showing memory impairment that does not improve with recognition testing. Objective: We sought to identify disease-dependent deterioration patterns by comparing elderly patients with secondary progressive MS (SPMS) and with aMCI using the Consortium to Establish a Registry for Alzheimer’s Disease test battery. Methods: This study included 120 age-, education- and gender-matched participants, including healthy controls (n=40), SPMS patients (n=40), and aMCI patients (n=40). Results: Episodic memory deficits appeared in the long-term course of SPMS. Deficits were associated with deterioration of executive function, but not impairment of memory storage as recognition was preserved in SPMS in contrast to the patients with aMCI. Conclusion: Through neuropsychological testing, MS-related episodic memory impairment due to deteriorated executive function can be distinguished from AD-related encoding and storage deficits. Hence, neuropsychological testing may help to identify AD-related pathology in SPMS patients.