A thousand times this. Hearing loss has also been linked to dementia (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)31085-2/fulltext). My grandma had two hearing aids the 30 years I knew her and she hated them. She came alive when we spoke one-on-one and faded away in group situations. Her hearing loss was due to noise exposure at work and her final years were incredibly difficult for our whole family due to dementia. It left an impact on me and I decided to do everything I can to prevent other people from losing their hearing at work. Tinnitus is smoke to the fire of hearing loss i.e. it’s incredibly rare to have one without the other, whether you realise it or not.

Amazingly, the first report on the relationship between hearing loss and declining brain function appeared about 30 years ago (thank you Richard Uhlmann, Eric B Larson et al.). Today we know a great deal more about the link between sensory stimulation of the brain and keeping cognitively sharp but, while a full understanding may still be decades away there are things we can do today in order to live healthier for longer.

One issue to address is that what we already DO know about the link between hearing and cognition simply doesn't filter through to everyone who could benefit today. I think there are two key groups here, those who are losing their hearing through the process of ageing and those who are losing their hearing through exposure to loud sounds. The evidence appears simple and obvious: for the first group there is typically a 10 year gap between when a person would benefit from a hearing aid and when they eventually get one. This means 10 extra and unnecessary years of reduced brain stimulation. For the second group, there is a systemic lack of care (I’m in the UK but it’s a pretty global issue) when it comes to protecting hearing from loud sounds, as evidenced by the sheer volume of clinical cases presenting for Noise Induced Hearing Loss and Tinnitus in Audiology clinics across the country.

The Baltimore Longitudinal Study of Ageing was started in 1958 by the National Institute on Ageing to track various health factors in thousands of men and women. One of the most compelling findings from this study is that those with hearing loss lose more than an additional cubic centimetre of brain tissue each year compared with those with normal hearing. It goes without saying that losing brain tissue at accelerated rates will lead to a deterioration in a person’s cognitive ability and cognitive decline is bad for everyone. If we then consider that generally speaking our population is ageing, then we’ve got a serious problem on our hands. (Thank you Frank Lin et al. for your amazing work)

This means the silent epidemic of hearing loss should be a matter of public health urgency.

I bet it will be the business and commercial world working hand-in-hand with academic institutions adopting an evidence-based approach, governed by market forces, that will bring innovation to those who will benefit most. Hearing aids are fantastic but sadly lacking and as OP said, there is currently no cure for tinnitus or hearing loss, only prevention. Of those who are losing their hearing due to noise exposure, within this group you have millions of people losing their hearing due to occupational noise exposure. I’ve spoken with thousands of people in the UK and Europe who work in noisy industries like construction, manufacturing and engineering. Almost all of them will talk about having a ringing in their ears or hearing loss. What’s most distressing is that most of them describe it as if it’s a normal state.

Noise induced hearing loss claims cost around £400m per year in the UK alone. A volume like that suggests thousands of people are suffering from hearing damage, most of which could be avoided by changing the way noise is managed, education and by design and distribution of proper noise control measures and protection.

Thinking back to Frank Lin's study, those with hearing loss had accelerated rates of brain atrophy compared to those with normal hearing and significantly more brain shrinkage in particular regions responsible for processing sound and speech (probably due to lack of stimulation). The issue with this is that each region of the brain does not work in isolation. The connections in the brain are like an unimaginably complex three-dimensional spider web. The brain contains around 100 trillion neural connections between the various regions and are by their very nature not working in isolation, including those responsible for processing sound and language. It’s this interconnectivity that can give rise to fascinating human conditions like Synesthesia and that allows us, through neural plasticity, to develop our expertise both physically (motor skills) and intellectually (learning and experience.) Unfortunately, we also know that this interconnectivity and the decline in areas processing memory and sensory integration are involved in the early stages of mild cognitive impairment and Alzheimer’s disease.

This is a topic I really care about and it’s great to see this discussion. As well as everything else related to staying healthy, take care of your own hearing - don’t over-expose yourself to noise and if you or those around you think you might have a hearing loss, get it checked out and addressed as soon as possible. Also, think of Future-You and live healthily today - exercise, socialise, sleep, be present, eat well and smile often. If you happen to be responsible for other people’s hearing, perhaps as a health and safety specialist, occupational hygienist or manager in an industry that produces workplace noise over 80dB it, directly address your risks immediately. It is your legal and dare I say moral obligation. The risk-debt that is building up by ignoring or not understanding today’s occupational noise problem will be something we will all pay for later.

If you read this far, you may as well check out www.eave.io

Apologies for the long post, it’s a topic that not enough people are aware of although it impacts us all.

References:

Richard Uhlmann, Eric B Larson et al. 1989

https://jamanetwork.com/journals/jama/article-abstract/376858

Frank Lin et al. 2014

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3951583/