Diagnostic Traps in Adult Onset Amnesia: How Autoimmune Encephalitis Mimics Neurodegeneration

Differentiating primary neurodegenerative conditions from secondary, reversible causes of cognitive impairment remains a cornerstone of clinical neurology. When short-term memory declines rapidly over weeks or months while remote memory, executive function, and visuospatial orientation remain intact, inflammatory pathways within the limbic system should be evaluated immediately.

Unlike Alzheimer's disease or vascular dementia, autoimmune limbic encephalitis involves acute or subacute autoimmune attacks directed against neuronal surface antigens like LGI1, NMDAR, CASPR2, or AMPAR. A comprehensive diagnostic workup includes CSF analysis, EEG monitoring for temporal epileptiform discharges, and systemic screening for underlying malignancies or thyroid autoimmunity. Identifying these autoantibodies allows clinicians to reverse neurological deficits using early immunomodulatory strategies before permanent hippocampal damage occurs