Abstracts

Rationale: There is a limited knowledge regarding the long-term psychiatric outcomes after treatment of autoimmune encephalitis. An improved understanding of these complications and associated risk factors can inform the diagnostic screening and counseling of the survivors of autoimmune encephalitis. Hence, we aimed to characterize long-term psychiatric symptoms and disorders and associated risk factors in patients with autoimmune encephalitis.

Methods: We retrospectively identified patients ages 18-100 treated at the New York University Langone Medical Center and other New York City hospitals from 2007-2019 with a diagnosis of 1) antibody receptor positive and clinically possible autoimmune encephalitis, 2) definite autoimmune limbic encephalitis, and 3) probable seronegative autoimmune encephalitis, using Graus diagnostic criteria. Patients were then evaluated prospectively using Mini Neuropsychiatric Inventory (MINI) 7.0.2 and Profile of Mood States-2 (POMS-2). We used descriptive analysis to assess the frequency of categorical variables, Fischer exact test for group differences in binary categorical variables and logistic regression to assess relationship between variables.

Results: 27 subjects (male=9, female=18) with a mean age of 32.39 ±16 years were included. Median time to follow-up was 3.28 years (IQR 2.24-8.81). Subtypes included anti-NMDAR (33%), anti-GAD65 (19%), anti-LGI1 (15%) and antibody negative (33%) autoimmune encephalitis. 41% of subjects had been previously diagnosed with a psychiatric disorder. 67% had a new diagnosis of a psychiatric disorder on follow-up (as per MINI) and 26% reported mood disturbance (as per POMS-2). New psychiatric diagnoses included Major Depression (37%), bipolar disorder 1(7.4% each), panic disorder, current (7.4%) & lifetime (11.2%), Agoraphobia and Social Anxiety Disorder (11.2% each), and Current Mild Alcohol Use Disorder (7.4%). Only 39% of those with a new psychiatric diagnosis were receiving treatment at the last follow-up. GAD-receptor ab positivity, acute symptomatic seizures during the encephalitis phase, an abnormal MRI and a high modified Rankin Scale score on last follow-up (p=0.03) were associated with a new psychiatric diagnosis on MINI on bivariate analysis. On multivariate analysis, only acute symptomatic seizures (OR 45, 95% CI 1.2-1608, p=0.036) predicted occurrence of a new psychiatric diagnosis on MINI.

Conclusions: There is a high prevalence of psychiatric comorbidity in patients with autoimmune encephalitis and a substantial proportion of these patients remain undertreated. Acute symptomatic seizures increase the risk of a new psychiatric diagnosis on follow-up.

Funding: Please list any funding that was received in support of this abstract.: National Center for Advancing Translational Sciences (NCATS); National Institutes of Health through Grant Award Number 2KL2TR001446-06A1.