Memory outcomes in patients with autoimmune encephalitis-a study of the Australian autoimmune encephalitis consortium.

Abstract

Background & Objective Patients with autoimmune encephalitis (AE) can present with a variety of memory complaints. However, it is difficult to draw strong conclusions regarding memory as there has been significant heterogeneity in the assessment of memory in this group. Methods 52 patients who met criteria for possible AE were recruited prospectively across four hospitals. Patients underwent a comprehensive examination of memory using 4 established scales of memory. Summary statistics were computed to compare memory scores to normative data. Independent samples t-tests were computed between different AE groups. Exploratory cluster analysis was performed to identify memory subgroups. Results Comparing AE cohort to normative data, none of the memory measures were significantly below expectations in the AE cohort. Frequency data demonstrated that 20% of the total cohort demonstrated impairments on delayed visual memory, acquisition of a word list and interference and long-delay recalls of this list. The anti-LGI-1 ab-mediated AE group performed poorer on the task of delayed story recall than the anti-NMDAR ab-mediated AE group. Exploratory cluster analysis identified 3 clusters-1) 20.93% of patients and characterised by scores above the normative mean, 2) 41.86% of patients and characterised by memory scores below the normative mean, and 3) 37.21% of patients which suggested heterogeneity in memory performances. Discussion While patients with AE can have similar memory scores compared to age/sex-matched non-AE counterparts, a frequency and cluster analysis suggests that a proportion of AE patients can present with memory impairment across tests of memory.