Psychiatric and behavioural sequelae following encephalitis: a systematic review and meta-analysis.

Survivors of encephalitis frequently experience chronic neuropsychiatric sequelae, yet the prevalence and patterns of mental health outcomes remain poorly characterized. We conducted a systematic review and meta-analysis to quantify the prevalence of psychiatric and behavioural symptoms following encephalitis. We also aimed to compare infectious with autoimmune encephalitis, explore specific aetiological associations as well as age-related differences. Following PRISMA guidelines, MEDLINE, EMBASE, PsycINFO, CINAHL, and PubMed were searched through 13 December 2024. Observational studies reporting psychiatric outcomes ≥3 months post-encephalitis were included. Two reviewers independently screened titles/abstracts and extracted data on symptom prevalence, study design, aetiology, and demographics. Random-effects meta-analyses estimated pooled prevalence of depression, anxiety, disinhibition, emotional instability, and other neuropsychiatric domains. Subgroup analyses compared infectious versus autoimmune causes and paediatric versus adult cohorts. Meta-regression assessed the influence of follow-up duration, sex percentage and cohort age. One hundred one studies (n = 4703 patients; weighted mean age 36.5 years) met inclusion. Across all aetiologies, pooled prevalence estimates included: depression, 26.9% (95% CI 22.2-32.3%); anxiety, 22.8% (95% CI 14.2-32.0%); disinhibition, 20.5% (95% CI 15.1-27.3%); emotional instability, 22.9% (95% CI 15.6-32.4%). Infectious encephalitis demonstrated higher rates of mood symptoms (75.2% versus 30.9% in autoimmune; P < 0.001). Meta-regression revealed that follow-up duration, mean cohort age, and female proportion influenced the prevalence of several neuropsychiatric symptoms. Heterogeneity was substantial across analyses, reflecting aetiologic, methodological, and demographic diversity in included studies. Psychiatric sequelae following encephalitis occur at rates comparable to neurological complications, with depression, anxiety, disinhibition, and emotional instability each affecting at least one-quarter of survivors. The substantial heterogeneity across studies highlights the need for prospective comparative cohorts, consistent diagnostic criteria, and the development of a standardized mental health outcome set to improve both care and research.