Short summary

Autoimmune encephalitis (AE) is a devastating neurological condition associated with significant long-term morbidity, affecting both young and elderly people. Recent emerging studies have shown compromised cognitive and social functioning in post-AE patients. In this clinical, cross-sectional study we will evaluate the cognitive, neurological and paraclinical long term consequences of the disease as well as patient quality of life and caregiver burden.

Rationale

In recent years, autoimmune neurological diseases, in which the immune system produces antibodies against cell-surface proteins in the brain, have become an emerging field. The antibodies are directly pathological causing autoimmune encephalitides (AE), presenting with symptoms such as impaired memory, psychiatric symptoms, seizures and movement disorders. Although these symptoms are commonly shared in all subtypes of autoimmune encephalitis, there are antibody-dependent variations in the different AE syndromes. The two most frequent syndromes are AE with antibodies against receptors of the N-methyl-D-aspartate type (NMDA) and the voltage-gated potassium channel associated protein (leucine-rich glioma inactivated 1; LGI1). In addition to anti-NMDA receptor and anti-LGI1 autoimmune encephalitis, more than 15 other cell surface antibodies associated with AE have been identified, and new antibodies are described at an astonishing pace of 2-3 per year. AE is often highly responsive to immunotherapy, with a good outcome if diagnosed and treated early. Prognosis depends on aggressive immunotherapy, often with corticosteroids, intravenous immunoglobulin, plasma exchange and in some cases anti-CD20 therapy or cyclophosphamide. Evaluation of patient outcomes, and thus prognosis, have been mostly done using physical examination with the modified Ranking Scale (mRS), originally developed for measuring the degree of disability of people who suffered a stroke. However, AE involves the brain more globally than a stroke and often involves the temporal lobes and limbic system responsible for memory, learning, behavior and emotions. Thus, knowledge of residual non-motor symptoms and cognitive deficits are scarce and often based on a short follow-up time of 1-2 years. Recent studies are beginning to unravel the long-term cognitive and social functioning outcomes of AE patients around the world. Not much is known about the socio-economic burden of AE both in relation to the patient and caregivers and to society. Denmark is known for its healthcare digitalization and a variety of National Health Registers based on the unique personal identification number. The National Health Registries can provide information on a variety of subjects such as contact with hospital system, diseases, treatments, cause of death, health economics, employment, income, educational level. In the present study, we aim to thoroughly evaluate long-term cognitive outcome, residual symptoms and quality of life in the National Danish AE cohort and their caregivers, which consists of all auto-antibody positive AE patients from 2009-2019. Additionally, we want to estimate the socio-economic burden of AE for patients and the healthcare system in Denmark.

Description of the cohort

All patients with antibody-positive, definite autoimmune encephalitis identified in Denmark from 2009-2022 and their primary caregiver. Patients are registered in the Danish Autoimmune Encephalitis Study (DANAIMS).

Data and biological material

Demographic data, neurological examination scores, neuropsychological testing scores, MRI/PET of the brain and categorical descriptions, blood and cerebrospinal fluid samples, questionnaire data.

Collaborating researchers and departments

Department of nuclear medicine, OUH

• Peter Grupe

Department of radiology, OUH

• Consultant Nina Nguyen

Department of clinical immunology, OUH

• Clinical lecturer, Anna Christine Nilsson

Department of Neurology, Charité Hospital Berlin

• Professor Carsten Finke

Publications associated with the project

Nissen MS, Ørvik MS, Nilsson AC, Ryding M, Lydolph M, Blaabjerg M. NMDA-receptor encephalitis in Denmark from 2009 to 2019: a national cohort study. J Neurol. 2022;269:1618-1630