Screening for neuronal antibodies in cognitive impairment and dementia clinics: a prospective multicenter study.

BACKGROUND: AIE can sometimes present as chronic and insidious, whereas some dementia patients develop symptoms at a young age or experience rapid cognitive decline. We aimed to assess the prevalence of antibody-mediated encephalitis in outpatients presenting with cognitive impairment. METHODS: One hundred ten Thai volunteers were recruited from three tertiary care centers: 23 patients with dementia and 87 patients with MCI. Serological tests for neuronal antibodies and Hashimoto’s antibodies (anti-TPO and anti-TG) were performed. RESULTS: The mean age of the participants was 68.82 ± 6.08 years, with a female-to-male ratio of 2.3:1. The onset of memory impairment was approximately 36 months (range from 0 to 180 months). Sixteen patients (14.5%) had abnormal blood tests, including 15 (13.6%) with Hashimoto’s antibodies and one (0.9%) with anti-LGI1. However, anti-TPO and anti-TG levels were significantly elevated in only 5 patients (4.5%). At the 1-year follow-up, 3 patients still had elevated levels of Hashimoto’s antibodies, while 1 patient with an anti-LGI1 antibody was repeatedly negative. All participants had no other symptoms that fulfilled the diagnostic criteria for Hashimoto’s encephalitis or AIE. CONCLUSIONS: Broad neuronal antibody screening appears to have low diagnostic yield and limited additional value in patients in their 60s with symptoms of cognitive impairment lasting longer than 36 months and without other significant neurological signs. CLINICAL TRIAL NUMBER: Not applicable.