• Slight Hearing Loss Means 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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  • Green Tea – a “smart” drug? by Dr Jack

    SYBO 1 year oldRoom For One More?

    In the Smart Drugs chapter of the book I wrote with Adrian Webster “Sort Your Brain Out” we argued that of the various nootropics available in this day and age it makes sense to give preference to substances that have been around for eons rather than the new kids on the block. This really is the only way you can enjoy the benefits without having to worry about the potential unknown long term problems and side effects.

    The brain benefits of regular coffee drinking were described, but due to space limitations we were only able to discuss a few other substances. This month’s blog highlights some of the many published studies that have indicated a wide variety of health benefits associated with regularly imbibing green tea – something that people have indeed been doing for hundreds of years.

    Green & Black

    Tea_grade_of_fermentationCamellia sinensis is the name of the plant that gives us white, yellow, green, black and oolong teas. Black tea has more than twice the amount of caffeine as green tea, whilst green tea has more polyphenols (the very antioxidant substances that mop up all those dangerous free radicals). The difference in concentrations of these substances can be accounted for by the fact that black tea requires fermentation before preparation – which increases the caffeine content and decreases the polyphenol content – whilst green tea is prepared from unfermented leaves.

    All The Tea In China

    GreenTeaPotGreen Tea has been used in traditional Chinese and Indian medicine for thousands of years where it has been exploited for it’s stimulant, diuretic and astringent properties; not to mention improving heart health, flatulence and body temperature regulation. The stimulant effects are thanks to the alkaloids contained within the tea leaf including caffeine, theobromine and theophylline. As green tea contains about half the caffeine of black tea and MUCH less than a cup of coffee, dosing yourself with green tea throughout the day is much less likely to disrupt your sleep come bedtime than the other options.

    Typing “green tea” into an internet search engine yields a huge number of websites dedicated to promoting the ubiquitous benefits of regular green tea ingestion to improve the effectiveness of exercise, improving weight loss and even helping to manage diabetes. Of course its always difficult to know which sources you can and can’t trust. Hard data is required to establish whether green tea really does help to ameliorate symptoms of the various complaints for which it has been traditionally recommended.

    Is Green Tea Really Good For You?

    Yes! When individual research studies are published in a peer-reviewed scientific journal they can provide evidence to support or reject any particular scientific hypothesis, but a single study cannot “prove” or “disprove” any given theory. Meta-analyses are much more powerful in this regard because they look at many different studies all investigating similar hypotheses. If, despite being conducted on a completely different group of subjects, often in a completely different location and undertaken by a different group of researchers, they all point towards the same conclusion this provides for a much more powerful argument to support, or refute, any given claim when the consensus points to a benefit. Just looking at the meta-analysis data it has been confirmed that green tea is effective at lowering blood pressure, reducing risk of several different cancers and improving cardiovascular/metabolic health, to name but a few.

    Any Brain Benefits of Green Tea?

    keep-calm-and-drink-green-teaDrinking green tea has long been associated with relaxation and, indeed, scientific investigation has now backed this up. Epigallocatechine-3-gallate, the most active of the tea polyphenols (known collectively as “catechins”) is found in much higher quantities in green tea than other teas and is known to inhibit an enzyme that converts cortisone to cortisol. Cortisol is a so-called stress hormone and cortisone the inactive form. By preventing the enzyme in question – 11 beta-hydroxysteroid Dehydrogenase Type 1 – from doing its job, the active ingredient of green tea is able to reduce levels of the stress hormone. (In case you were wondering, the other 5 catechins are: catechin, gallaogatechin, epicatechin, epigallocatechin and epicatechin gallate).

    Can Green Tea Can Improve Cognition?

    Yes! Anecdotal accounts of the brain benefits of regular tea drinking in the elderly inspired research to establish whether green tea really could improve cognition. Over the last ten years huge amounts of data have been generated on this topic. The more green tea a person consumes, the lower prevalence of cognitive impairment (Full article available for free). Early research trying to ascertain the mechanism by which such benefits are realised demonstrated that spatial cognition was improved in rats that drank water infused with polyphenols from green tea (full article available for free).

    In the last few years experiments dosing healthy, younger humans with green tea versus placebo have demonstrated an increase in functional connectivity between frontal and parietal brain areas during a working memory task (Full article available for free). Bearing in mind that improvements in working memory can translate into better fluid intelligence and therefore a higher score in the IQ test – swapping green tea into your daily hot drink regime might make sense for your brain’s sake as well as your body’s.

    As well as these monthly blogs you can follow me on twitter by clicking here. It’s always great to hear your suggestions on topics for my brain blogs, so please do get in touch by clicking here.

    I also do a weekly science podcast called Geek Chic’s Weird Science which you can download for free from iTunes or alternatively, if you’re not an iPhone or iPad user, you can download/stream it from a variety of online sources such as Podbay, Libsyn, and PodcastChart, amongst others!

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