With more than 12% of adults of all ages affected by a decreased sense of smell or other olfactory system disorders, and an even higher percentage in adults ages 65 and older, attaining a deeper understanding of the mechanisms involved in olfactory function is an important step in identifying more effective therapeutic options than those in existence today.
New research programs and collaborations in Duke’s Department of Head and Neck Surgery & Communication Sciences are taking shape under the leadership of otolaryngologist Bradley J. Goldstein, MD, PhD, who specializes in rhinology and sinus surgery. He discusses the limitations of current treatments, the ways in which Duke is working to improve diagnostics and treatments, and the hope for future therapeutic strategies for olfactory disorders.
Q: Why is olfactory function decline an important area of research for Duke?
Goldstein: It’s a big problem that is increasing with our aging population, and these disorders are frustrating for both physicians and patients because we lack sufficient treatment options. There are two broad categories of causes of olfactory disorders:
- Conductive/obstructive problems, which can be subtle but are often treatable. These can be due to allergies, inflammation, or infection. For these, we have medical and surgical options that can offer relief to some, but not all, patients.
- Problems that damage the delicate sensory structures in the olfactory pathway, which are quite common but poorly understood. Post-viral damage, post-head trauma damage, or wear and tear from aging can all potentially impair peripheral olfactory system function.
For both of these categories, we believe there are potential new treatments on the horizon, and that’s what is driving our research program. We also believe it’s important to raise awareness about unproven, potentially harmful therapies, as there’s a lot of misinformation in the public domain. Another area of research is the association between olfactory loss and neurodegenerative conditions, such as Alzheimer’s or Parkinson’s disease.
Q: Are there any new strategies available now that can improve symptoms?
Goldstein: For patients with partial loss of their sense of smell or diminished olfactory function, we sometimes consider newer strategies like olfactory training therapy, which is analogous to physical therapy for strengthening damaged muscles, and has shown some promise in early studies. In this therapy, patients sniff a few different categories of odors twice a day, and over time, that stimulation of the olfactory system can actually help it recover from damage. It’s easy to do, with no risks or harmful side effects, and high-quality studies have shown that patients with a variety of hyposmia conditions do seem to recover better. It’s not magic, but in appropriate patients, it can be helpful.
Q: What plans does Duke have to improve diagnostics and find new treatments for these conditions?
Goldstein: We’re currently developing a new smell disorders clinic to thoroughly evaluate patients with olfactory complaints and investigate new treatment options. There aren’t many specialty clinics like this one—we’ll be able to take the time required for complete evaluation and assessment, detailed physical examination, targeted imaging, and nasal endoscopy when indicated. We’re very eager to give patients and their providers this new clinic option.
Another exciting development is our new collaboration with the Duke Center for the Study of Aging and Human Development. The center’s clinicians and researchers have worked with vision, hearing, and cognitive decline in older patients, but until now there hasn’t been a formal focus on olfactory function decline. We see a unique potential in this collaboration to develop new therapies for aging-related sensory declines and further study of conditions like Alzheimer’s disease that are associated with early olfactory function loss.
Q: What are the promising areas of research that could result in future treatments?
Goldstein: There’s a lot of excitement around new therapeutic strategies for certain olfactory problems, but they’re not yet ready for human trials. One area for optimism is viral gene therapies that can be delivered directly to the nose for specific forms of olfactory loss. Another area being investigated is cell-based therapies: In mouse models, we were able to see that delivering an appropriate neural progenitor cell suspension to the olfactory area resulted in the production of new olfactory neurons that improved function. Repurposing available medications that may have a role in stimulating recovery after nerve damage or developing implants to stimulate the olfactory nerves are other promising possibilities and worthy of much more study.