Regenerating smell in neurodegenerative disease -translating theory into therapy

Quantitative and qualitative olfactory dysfunction are one of the earliest and most prevalent symptoms across neurodegenerative diseases, notably Parkinson's and Alzheimer's disease. These pathologies may spread bidirectionally between the peripheral olfactory system and central brain regions, supporting a model in which the olfactory system represents both an early marker and a conduit for disease propagation. This short communication aims to investigate the potential of Platelet Rich Plasma (PRP) to treat smell alteration in the neurodegenerative diseases.

We conducted a review of the literature to extract articles that discussed PRP use in the context of olfactory disorders.

12 studies were identified; 7 studies on COVID-19, 2 on unspecific smell loss, 1 on traumatic anosmia, 1 on nasal polyposis and 1 illustrated the use of PRP in long-term persistent anosmia (> 25 years).

Post COVID-19 olfactory impairment has provided insights into mechanisms of smell loss and therapeutic strategies. While olfactory training remains the best studied intervention, its benefits are modest, inconsistent, and often limited in cases with central nervous system involvement. PRP has emerged as a promising candidate due to its growth factors and immunomodulatory properties. Preclinical studies demonstrate that intranasal PRP can enhance neurogenesis, reduce neuroinflammation, and improve olfactory and cognitive outcomes in animal models of Parkinson's and Alzheimer's disease. Early clinical observations also suggest potential benefit in longstanding anosmia of diverse etiologies. Future research should define optimal delivery routes, dosing, and long-term efficacy, with well-designed clinical trials needed to translate these experimental findings into therapeutic applications.