Research update: A New Hypothesis for Understanding Cognitive Decline
- Koorosh Nejad
- Jun 14
- 3 min read
Updated: 6 days ago
There is some interesting research on the human auditory system and how hearing loss affects humans' cognitive function. I thought I should share a summary of two recent research papers with you in this post. For a full research paper about human cognition, please see the reference section of this post.
How Losing Your Hearing Can Supercharge Your Other Senses
The sensory cortex, the part of the brain responsible for processing input from our five senses, isn’t divided into isolated, self-contained areas, each responsible for one sense, and one sense only. Instead, it functions as a highly connected system, where each sensory region works together and shares information to help us interpret and respond to what is happening around us.
The article argues that as our senses of hearing, vision, touch, smell, and taste diminish, our brains compensate for what is lost and find new ways to maximise the sensory input we have.
The auditory cortex is the region responsible for processing sound, but when hearing is lost, the brain doesn’t simply let this area go dark and unused. Instead, it rewires itself through a process called cross-modal neuroplasticity, where other senses—such as vision and touch—step in and take over parts of the auditory cortex. Essentially, the brain repurposes its resources to make the most of the sensory information it still receives. This has been confirmed by multiple functional MRI studies, which show that in people with hearing loss, the auditory cortex is restructured and repurposed to enhance other senses.
Our vision is usually the main sense to step in and take control if we lose our hearing. People who are deaf or hard of hearing learn how to “hear with their eyes,” relying on visual cues such as sign language and body language, lip-reading, and environmental signals to interpret their sound-free world.
The good news is that the brain's neuroplasticity allows reversal of sensory allocation of cognitive resources back to the auditory cortex. The brain scan in the comparison shots in the above comparison demonstrates how the cognitive resources have been reallocated back from vision to the auditory cortex of the patient's brain after 6 months of using hearing aids.
The Cognitive Maladaptation Hypothesis: A new theory on hearing and brain health
The bad news is that, according to this theory, over time, these adaptive changes may become maladaptive, resulting in the inaccurate reallocation and inefficient processing of sensory input, increased mental effort, and greater cognitive fatigue. Rather than simply filling in the blanks, the cognitive maladaptation hypothesis suggests that the brain may recalibrate in response to suboptimal input from hearing and vision, thereby causing confusion and straining cognitive resources.
One study cited in the article, for example, found that adults with untreated age-related hearing loss showed earlier frontal-lobe responses on auditory tests, and those early responses were linked to worse speech-in-noise understanding. In other words, the brain might be “jumping the gun,” trying too hard to compensate, but doing so inefficiently.
The result? A possible vicious cycle: untreated hearing and/or vision loss may lead to brain changes, which reduce auditory and visual processing efficiency and increase mental strain, ultimately contributing to long-term degradation and cognitive issues.
Takeaways from these articles
If you feel your vision or your hearing is suboptimal, make sure to take action quickly.
When should I start addressing my hearing loss?
My advice is to treat your hearing loss like other health issues; the sooner, the better. If one of your teeth is sensitive to cold or warm beverages, it can be a sign of decay forming in that tooth. Early treatment of a toothache could be much more effective from a financial, comfort and effectiveness of the treatment points of view. This is quite valid for other health matters. As you noticed in this article, a hearing loss could cause other health issues, including reallocation of cognitive resources in your brain, which may not be fully reversible when you decide to start managing your hearing loss with hearing aids. Often, the maladaptation shows itself as a lack of speech clarity in noisy situations.
Did you enjoy this article?
If you found this article useful, please click on one of the social share buttons below and share it with a friend looking for professional advice on hearing aids and hearing care. After all, sharing is caring. Thank you.
I absolutely agree. All the studies point to the fact that the earlier you start using a HA the better results you achieve regarding understanding speech.
The paradox is that you are inclined to make excuses (I have a cold, it is noisy, another person attending also could not hear).
I was fitted with a hearing for mild hearing loss by Mr. Nejad and I am very satisfied with the result.
Excellent article. It all makes sense.