Researchers at the University of Colorado Boulder are investigating the relationship between hearing loss and cognitive decline through detailed studies of brain activity and neural reorganization. A seminal 2011 study from Johns Hopkins University found that over 12 years, people with mild hearing loss were twice as likely to be diagnosed with dementia, while those with moderate to severe hearing loss were three to five times as likely. In 2017, the Lancet Commission on Dementia Prevention identified hearing loss as the “single largest potentially modifiable risk factor for dementia.” However, whether hearing loss causes cognitive decline and what interventions might help remain unclear.
Professor Anu Sharma’s research demonstrates that even mild hearing loss triggers cross-modal plasticity—the brain’s reorganization to adapt to sensory deprivation. Using EEG with 128 electrodes to measure brain activity while participants processed sounds and visual stimuli, her studies show that even in mild hearing loss, the brain repurposes auditory cortex regions to assist other senses. More significantly, when processing sound, people with hearing loss show limited activation in the auditory cortex while brain regions for working memory and cognition activate heavily. “Even as early as mild hearing loss, listening becomes effortful,” Sharma explained. Some theorists propose this extra cognitive load consumes “cognitive reserve,” increasing dementia risk later in life.
A 2020 study published by Sharma’s lab found that when 21 adults with untreated mild to moderate hearing loss wore hearing aids for six months, their brains began resembling those of people with normal hearing again, and most scored better on cognitive tests. However, larger studies have yielded mixed results. One 2023 randomized controlled trial showed hearing aids did not reduce cognitive decline population-wide but did in specific subgroups including people with cardiovascular disease. In 2025, Sharma and colleague Vinaya Manchaiah launched a five-year randomized controlled trial with $3.5 million NIH funding, recruiting 280 people with early untreated hearing loss divided into four groups: prescription hearing aids with professional fitting; over-the-counter aids with in-person audiologist support; OTC aids with online support; and OTC self-fit groups. Approximately 30% of adults over age 50 have age-related hearing loss, though only 15% of those who could benefit from hearing aids in the United States use them.
This article is an AI-assisted summary. All facts and figures are drawn from the original report: https://www.colorado.edu/coloradan/2026/03/09/cu-researchers-study-potential-links-between-hearing-loss-and-dementia