Neuropsychiatric Features of Individuals With LGI1-Antibody Encephalitis

OBJECTIVE: Leucine-rich glioma-inactivated 1 antibody (LGI1-Ab) encephalitis is one of the most common forms of autoimmune encephalitis and is associated with prominent psychiatric features. Psychiatric phenotyping of this condition has relied on small studies and has lacked detail. METHODS: In this retrospective study, the authors reviewed the psychiatric symptomatology and clinical course among patients with a confirmed diagnosis of LGI1-Ab encephalitis. RESULTS: The mean±SD age of the study sample (N=31) was 60.7±14.2 years; 71% of patients were men. The time to diagnosis was 4.9±5.8 months, and the follow-up time was 55.8±36.7 months. Eighteen patients had documented hyponatremia, and 22 were treated as inpatients. Psychiatric (71%), cognitive (81%), and neurological (84%) symptoms were present at similar rates, despite 97% of the patients coming from neurology referrals. Patients had a diverse range of seizures, including faciobrachial dystonic seizures. Of 19 patients undergoing detailed psychometric analysis, impairments were noted in memory or orientation (100%), executive function (63%), naming (47%), processing speed (37%), attention (32%), verbal fluency (26%), language (11%), and visuospatial abilities (11%). Patients had psychotic symptoms (42%), agitation or aggression (39%), emotional lability (35%), anxiety (26%), and subjective experiential phenomena (16%). Many patients had psychiatric sequelae that resolved after treatment, but a modest proportion of patients experienced ongoing apathy (6%), behavioral disinhibition (13%), obsessive-compulsive disorder (10%), subjective experiential phenomena (13%), and sleep disorders (29%). CONCLUSIONS: These findings show that cognitive impairment and psychopathology are frequent in LGI1-Ab encephalitis. Future research could examine neuroimaging, psychiatric symptoms, and cognitive deficits in further detail.