Neurofilament Light Chain as a Biomarker in Geriatric Psychiatry Practice: A Narrative Review

Area of Science:

• Geriatric Psychiatry
• Neuroscience
• Biomarker Research

Background:

• Neurofilament light chain (NfL) is an axonal protein released upon neuroaxonal injury.
• Blood NfL measurement is a recognized marker for neurodegeneration.
• Its utility in geriatric psychiatry requires further definition.

Purpose of the Study:

• To review studies on serum/plasma NfL in older adults with neurodegenerative or psychiatric disorders.
• To synthesize data on normative values, determinants, and diagnostic comparisons.
• To develop a clinical interpretative framework for blood NfL in geriatric psychiatry.

Main Methods:

• Narrative review of peer-reviewed studies.
• Searched MEDLINE/PubMed up to October 31, 2025.
• Synthesized data on NfL levels, biological factors, and diagnostic associations.

Main Results:

• Blood NfL increases with age and is influenced by comorbidities (e.g., renal function).
• Neurodegenerative diseases show higher NfL than psychiatric disorders; most psychiatric conditions overlap with age-adjusted norms.
• Higher baseline NfL and steeper increases correlate with neurodegeneration risk in mild behavioral impairment and late-onset psychiatric syndromes.

Conclusions:

• Blood NfL interpretation in geriatric psychiatry should integrate age, comorbidities, clinical context, and longitudinal changes.
• Age- and comorbidity-adjusted NfL aids risk stratification.
• NfL can serve as an adjunctive biomarker to identify patients needing further neurological assessment or monitoring.