Each year, more than 300 cochlear implant surgeries are performed at Vanderbilt University Medical Center, making it the highest-volume center in the country. Unlike hearing aids, which largely amplify sounds, cochlear implants process sounds and send signals directly to the auditory nerve, which relays this information to the brain. The brain recognizes those signals as sounds, but it takes time after surgery for the brain to accurately interpret the new electrical signals.
Researchers in VUMC’s Implantables, Hearing Enhancement and Amplification Research (I HEAR) Laboratory have launched a study of neuroplasticity, or the brain’s ability to adapt to new information, in cochlear implant outcomes.
“After cochlear implant surgery, neural networks must reorganize in order to process the new sound information coming from the device,” said René Gifford, PhD, Fred H. Bess Professor of Audiology and director of the I HEAR Laboratory in the department of Hearing and Speech Sciences. “Previous studies from our lab have measured some of the changes in brain activity following cochlear implantation using functional near-infrared spectroscopy (fNIRS). While cochlear implants dramatically change how the brain responds to sound — a mark of neuroplasticity — we also know that some medications, like donepezil can further enhance neuroplasticity. Donepezil is one of the most commonly prescribed medications for enhancing cognition in patients with Alzheimer’s disease and has not yet been evaluated in conjunction with hearing rehabilitation.”
In this study, “Effect of Donepezil on Speech Recognition in Cochlear Implant Users,” participants will increase their daily cochlear implant use while taking either donepezil or a placebo for three months. According to Gifford, because there are no FDA-approved medications or therapeutics for sensorineural hearing loss, findings may support the use of neuroplasticity-promoting agents for hearing rehabilitation.
“Cochlear implants can be life-changing for many adults, but some cochlear implant recipients still struggle with speech understanding, especially in noisy environments. The results from this study may offer hope for these patients,” said Ansley Kunnath, study coordinator and MD/PhD candidate. “Decades of research have shown us that cholinergic drugs like donepezil promote neuroplasticity in the auditory cortex, but this is the first study to apply this approach to cochlear implant outcomes through a randomized controlled trial.”
“This could have implications for other sensory disorders as well,” Gifford added. “Data from our lab suggest that increasing daily cochlear implant wear time improves speech recognition. We hypothesize that donepezil will enhance these benefits even further.”
The study, which began in May and will continue enrolling patients until December 2024, is funded by a grant from the Vanderbilt Institute for Clinical and Translational Research (VICTR). Study participation involves three study visits to the I HEAR Lab — at the beginning of the study, at one month and at three months. Participants will perform tasks of speech understanding, cognition and brain activity in response to both auditory and visual stimuli via fNIRS neuroimaging.
Adult cochlear implant users must be 18 years or older, physically healthy, not pregnant or nursing and have at least six months of cochlear implant experience. Other criteria include:
- Onset of deafness after age 5
- No history of neurologic disorders, sensory disorders, visual impairment, traumatic brain injury or structural brain abnormalities
- No smoking or use of nicotine products in the past month
- No known allergy to donepezil or piperidine derivatives
- No current use of cholinergic or anticholinergic medications
- Effective contraception or abstinence during the study for all patients with childbearing potential
“This study provides an exciting and unique opportunity to pilot the use of a well-established medication on the market with the intent to improve outcomes for adults with cochlear implants,” said Aaron Moberly, MD, Guy M. Maness Professor of Otolaryngology. “We hope to see that this medication will enhance plasticity and adaptation to sounds provided by a cochlear implant.”
Patients enrolled in the study will receive a $50 gift card for each visit and can be reimbursed for travel expenses. Those interested can contact study coordinator Ansley Kunnath at ansley.j.kunnath@vanderbilt.edu.
