Author Response: Neurofilament Light Chain Levels in Anti-NMDAR Encephalitis and Primary Psychiatric Psychosis.

Abstract

We appreciate the comments of Dr. Vale on our study,1 reminding us that psychosis is a severe ailment and that patients may benefit from CSF studies. As shown by most of our work, we agree that CSF studies should be reincorporated in the evaluation of patients with new onset psychosis.1,2 Dr. Vale also indicates that there are other types of autoimmune encephalitis (AE), and the detection of NMDA receptors (NMDAR) antibodies is not essential for AE diagnosis. We are aware of this concept.3 As indicated in our manuscript, most cases of AE can associate with symptoms of psychosis, but the presence of concurrent neurologic alterations readily excludes a primary psychiatric etiology on clinical grounds. By contrast, the initial symptoms of anti-NMDAR encephalitis can mimic to perfection a first episode of psychosis due to a primary psychiatric disorder.2,4 For this reason, we narrowed our study to this specific AE. Regardless of whether neurofilament light chain (NfL) levels can be found to be elevated in many disorders with neuronal/axonal damage, determination of NfL showed clinical utility in the context of our study.