Clinical features, etiological spectrum, and outcomes of neurological patients initially presenting with psychiatric...

Neurological disorders can manifest with psychiatric symptoms as the initial presentation (PSIP), leading to diagnostic challenges and delayed treatment. Data on this patient population remain limited.

We conducted a retrospective cohort study of patients admitted to a tertiary neurology department between 2019 and 2023 with PSIP. A structured screening protocol using predefined behavioral keywords was applied, followed by independent case review by two neurologists and a psychiatrist to confirm eligibility. Final diagnoses were adjudicated by consensus using contemporary diagnostic criteria. Poor outcome was defined as modified Rankin Scale score >2 at discharge. Multivariable logistic regression was used to identify independent predictors of poor outcome, and a risk score was developed based on these factors.

Of 16,473 screened admissions, 76 patients (mean age 55.8 ± 18.2 years; 42.1% female) met inclusion criteria. Most patients presented with acute-onset (92.1%) non-specific behavioral disturbance (63.2%), and nearly one-third (31.6%) had isolated psychiatric symptoms without any accompanying neurological signs. The leading etiologies were CNS infections (55.3%), predominantly viral encephalitis (40.8%), followed by cerebrovascular diseases (14.5%) and autoimmune encephalitis (13.2%). Poor outcome occurred in 32 patients (42.1%). Independent predictors of poor outcome were hyponatremia on admission (OR, 3.9; 95% CI, 1.3-11.8), viral encephalitis etiology (OR, 3.1; 95% CI, 1.1-8.7), and ICU admission (OR, 4.8; 95% CI, 1.3-17.6). A risk score combining these three factors effectively stratified patients (AUC 0.88; 95% CI, 0.80-0.96), with poor outcome rates ranging from 7.1% (score 0) to 100% (score 3). Subgroup analyses revealed that among viral encephalitis patients, those with PSIP had significantly higher rates of hyponatremia (41.9% vs. 15.2%, p = 0.002) and poorer outcomes (58.1% vs. 88.4% good outcome, p < 0.001) compared to those without PSIP. Additionally, patients with isolated psychiatric symptoms were younger and had a higher proportion of autoimmune encephalitis (20.8% vs. 9.6%).

PSIP represents a critical clinical situation in which underlying neurological disorders, particularly viral encephalitis and autoimmune encephalitis are common. Hyponatremia serves as a readily available diagnostic clue and independent predictor of poor prognosis. The absence of neurological signs does not exclude serious underlying pathology. However, these findings are derived from a single tertiary center with a modest sample size and require validation in broader populations. Early comprehensive evaluation, including CSF analysis and neuroimaging, is essential to improve outcomes in this diagnostically challenging population.