Exosome-derived biomarkers as non-invasive tools in stroke, Parkinson's disease, and Alzheimer's disease.

Neurological disorders, including stroke, Parkinson's disease (PD), and Alzheimer's disease (AD), are among the most prevalent and debilitating neuropathological conditions, affecting over 50 million people globally. Effective prevention and treatment strategies require a comprehensive understanding of reliable and disease-specific biomarkers. Such insights can enhance diagnostic precision, enable early detection, and support the development of targeted therapeutic approaches. In this review, we focus on exosome-derived proteins and small non-coding RNAs as promising non-invasive biomarkers for stroke, PD, and AD, given the accessibility and stability of exosomes in biological fluids. Furthermore, we examine their potential diagnostic and therapeutic relevance, emphasizing their functional roles, specificity, and sensitivity. Finally, we discuss current limitations, emerging challenges, and future research directions to guide the advancement of exosome-based biomarker discovery and clinical translation in neurological disorders. However, we emphasize that the comparative effectiveness of exosomal microRNAs (miRNAs) versus protein biomarkers requires direct validation in future head‑to‑head cohort studies.