Serum Neurofilament Light as a Neuropsychiatric Disorder Screening Test in Psychiatric Emergency Settings

The authors evaluated serum neurofilament light chain (sNfL) as a blood-based biomarker to distinguish primary psychiatric disorders from psychiatric presentations of neurological or general medical etiology (i.e., neuropsychiatric disorders) in psychiatric emergency departments (PEDs), where rapid diagnosis is essential and access to advanced tests is often limited.

Data were collected from 846 patients with psychiatric disorders (17% anxiety, 34% mood, 9% personality, 32% psychotic, and 7% substance use) and 20 patients with neuropsychiatric disorders (35% neurocognitive, 20% delirium, and 55% general medical causes). sNfL levels were measured with the SIMOA (Single Molecule Array) platform. Analysis of covariance and logistic regression were conducted to assess sNfL differences between psychiatric and neuropsychiatric patients. Receiver operating characteristic curve analysis was used to determine diagnostic accuracy, with Youden's index employed to identify optimal thresholds.

In analyses adjusted for age and sex, patients with neuropsychiatric disorders had significantly higher sNfL levels, compared with those with psychiatric disorders. The effect size was moderate (partial η²=0.24). Logistic regression confirmed that sNfL levels strongly predicted the diagnostic group. The optimal cutoff for sNfL was 30.6 pg/mL, with a sensitivity of 0.90 and specificity of 0.94. Subgroup analyses suggested that age-specific thresholds could improve diagnostic accuracy.

sNfL is a promising biomarker for rapid differentiation in PEDs between primary psychiatric disorders and psychiatric conditions of general medical or neurological origins, potentially improving diagnostic accuracy and speed. Future research is needed with more diverse, prospective cohorts with a wider range of diseases to replicate the clinical utility of sNfL.