• Even Slight Hearing Loss Is Associated with Cognitive Impairment

    My best mate’s dad is stubborn to say the least. Two heart attacks didn’t convince him it was time to stop smoking. And when his hearing started to go he refused to wear a hearing aid. That was 10 years ago. Today this has progressed to the stage of being really hard of hearing. He’s a quiet man by nature, usually on the edge of a discussion rather than at the centre of the debate, but his comments were always incisive and insightful when he chose to contribute. With four kids and five grandkids there were always plenty of other voices clamouring for centre stage, so he was happy just to listen in from the fringes.

    Over the past decade, when I accompany them on their annual family holiday, I’ve noticed that his contributions to the conversations were becoming less frequent. At first I just thought he was becoming more melancholy in his post-retirement years, but then in the last few years it became apparent that he simply couldn’t hear what people were saying, whether they were speaking to him or each other.

    Well into his seventies now he still manages all the accounts for the family business and had mentioned once or twice over the years, when I drop in to say hi on Christmas Day, that simple invoicing jobs were taking him much longer than usual. Straight-forward office management chores were taking all day rather then just being a few hours work in the morning or afternoon.

    He puts it down to the inexorable processes of ageing, which seemed perfectly reasonable. But research published this month in JAMA Otolaryngology makes me question this assumption. I now suspect that his dogged resistance to getting hearing aids may have done him a disservice. When it comes to the important task of holding onto your marbles in your 50’s and beyond, pouncing immediately on hearing loss is vital. Eliminating hearing loss not only fights against age-related cognitive impairment, the latest estimates indicate that it could even lead to a reduction of 9% in the diagnosis of new cases of dementia.

    It turns out that just a small decline in hearing ability predicts a fairly alarming drop in cognitive power and even more so for every additional 10dB reduction in hearing. Bearing in mind the concept of neuroplasticity, when mild hearing loss leaves a person unable to catch everything that is being said, less information will end up being pushed through the areas of the brain that extract meaning from and mull over the words that have been uttered. The less information that is pushed though any given brain network, the less the brain will selectively reinforce those pathways.

    The study under consideration here was published by Justin Golub and colleagues at Columbia University in New York City who evaluated the level of hearing loss and cognitive abilities of over 6,000 people in their fifties and upward. It provides strong evidence that the hearing impairment-related cognitive decline occurs with a drop of just 10 dB from the level considered to be perfect hearing.

    As someone that spent the early part of his teenage years standing too close to the speakers at gigs and raves, I’ve know for a long time that the hearing in my left ear is not as good as my right. For the time being this isn’t a major problem because I rarely find myself unable to hear what people are saying. When it does happen, usually only in very noisy environments, I simply switch sides. But I never miss out completely on what is being said to me. I remain deeply involved (some would say too much) in any conversation.

    Thanks to Golub and colleagues, over the next few decades I’ll be paying extra close attention to any deterioration to the hearing in my right ear to ensure I maintain my cognitive capabilities for as long as possible. Who knows, thanks to these insights I might even dodge dementia. As I described in my last book The Science Of Sin – it’s vitally important to our physical and mental health to stay socially connected to other people in our communities. Anti-social behaviour is one thing that can leave people socially isolated, but even mild hearing loss can distance people from the cognitively nourishing impact of interaction with other people. In the words of Golub himself:

    “Most
    people with hearing loss believe they can go about their lives just fine
    without treatment, and maybe some can. But hearing loss is not benign. It has
    been linked to social isolation, depression, cognitive decline, and dementia.
    Hearing loss should be treated. This study suggests the earlier, the better.”

    In addition to these monthly blogs I regularly tweet about the latest fascinating titbits of neuroscience research I find in the lay press (@drjacklewis) and now have a YouTube channel called Brain Man VR where I review Virtual Reality games and experiences every week. Currently there are 9 to choose from, but as a new episode is released every Tuesday, there’ll be more than that by now…

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