The article, Autoimmune Encephalitis Resembling Dementia Syndromes, explores the occurrence of autoimmune encephalitis (AIE) in middle-aged and older patients, highlighting how it can mimic neurodegenerative dementia. This study examined patients with anti-leucine-rich glioma-inactivated 1 (LGI1), anti-NMDA receptor (NMDAR), anti-GABA-B receptor (GABABR), or anti-contactin-associated protein-like 2 (CASPR2) encephalitis, specifically focusing on those aged 45 and older who met dementia criteria without experiencing prominent early seizures. The study revealed that AIE often manifests with cognitive decline and behavioral symptoms similar to dementia, making misdiagnosis a potential risk if clinical signs are misinterpreted.
Out of 290 patients, 175 were over 45 years old, and 67 met the dementia criteria, with nearly half displaying rapid cognitive deterioration. Interestingly, most of these patients responded well to immunotherapy, indicating the importance of distinguishing AIE from neurodegenerative conditions. Subtle seizures were often present but were frequently overlooked, which contributed to delayed treatment. The study underscores specific "red flags" for AIE, such as rapidly progressive cognitive decline, subtle seizures, and abnormalities in ancillary testing that are not typical of neurodegenerative dementia.
The findings suggest that while MRI and cerebrospinal fluid (CSF) tests might not always reveal inflammatory signs, biomarkers like tau and amyloid-beta proteins, commonly used to assess dementia, can sometimes show abnormal results in AIE. These atypical results may prompt a mistaken diagnosis of neurodegeneration, emphasizing the need for antibody testing when AIE is suspected. The study advocates for earlier antibody testing in patients presenting with rapid dementia symptoms, especially when imaging and CSF findings do not align with typical dementia profiles.
Ultimately, the study highlights that accurate and timely diagnosis of AIE is crucial, as patients often benefit significantly from immunotherapy. The authors call for increased awareness among physicians about AIE as a potential differential diagnosis for rapidly progressive dementia, particularly in patients aged 45 and older.
