MICHAEL MOSLEY: The test that shows Covid has made us dumber… and what to do about it

Are we becoming slower in understanding? The answer should worry us all.

A few years ago I made a TV program called The Great British Intelligence Test, in which we measured the brainpower of the nation and conducted the largest intelligence experiment of its kind.

More than a quarter of a million people have taken our special IQ test, developed for us by scientists from the Department of Brain Sciences at Imperial College London. (You can see what we’re doing to people by searching online for “Michael Mosley IQ test.”)

Unsurprisingly, we found that when it came to problem solving, people in their early twenties performed best; they have more knowledge on their side than, say, a teenager, but their brains also work faster than those of middle-aged or older people.

The reason problem-solving skills decline with age is partly related to how well the connections between your brain cells are insulated.

As we age, the myelin sheath that surrounds the brain’s wiring thins and slows down communication between our neurons. Our brains literally slow down.

But there was good news for older people; while other cognitive skills declined with age, verbal ability increased, peaking in people in their 70s. Curiously, cat lovers scored higher on verbal skills than dog lovers (though that may have been a coincidence), as did book readers and people who love fruits and vegetables.

But the biggest surprise came much later, long after the program had aired on TV.

That’s because the test was put online in 2019, before the Covid pandemic swept the world, and researchers continued collecting data well into 2020, when the outbreak was at its worst.

At that point they had included questions about whether people had had Covid and, if so, how it affected them.

They found that people who were infected scored lower on IQ tests, especially when it came to something called executive function, a measure of mental skills such as memory, flexible thinking and self-control. If your executive function is compromised, it can make it difficult to concentrate, follow directions, and deal with emotions.

The team has since completed a larger study of more than 112,000 people, which was published last month in the New England Journal of Medicine.

This confirmed the long-term impact Covid can have on our brains. People with mild infections lost a few IQ points, but those who developed a long bout of Covid-19 saw an average IQ drop of around six points.

And the results of this study fit into another, more worrying trend, which is that IQ scores have been declining worldwide since the 1970s. In a 2018 study published in Proceedings of the National Academy of Sciences, researchers looked at the IQ scores of young men in Norway, recorded when they were called up for mandatory military service. Over a forty-year period beginning in 1970, there was a steady decline of about seven points per generation.

This phenomenon has now been recognized in other countries, including the US and Great Britain.

While no one really knows exactly what’s going on, there is some suggestion that it could be related to the rising rates of obesity and our growing reliance on ultra-processed foods, both of which are bad for the brain.

Being struck by a contagious disease, especially one that persists (like Covid), is also a surefire way to lower your IQ score.

There is also a growing concern among some researchers I’ve spoken to that the rise of artificial intelligence will increase the downward pressure on human intelligence as we increasingly rely on machines to do our thinking for us.

So what can you do to keep your brain in good shape?

There is plenty of evidence that eating a healthy diet can make a big difference. A 2021 study of 70-year-olds by the University of Edinburgh found that those who followed a Mediterranean diet (rich in olive oil, nuts, vegetables and fish) scored highest on a range of memory and thinking tests.

Even more surprising, playing computer games also seems to be good for improving your cognitive skills. That’s certainly what we found in The Great British Intelligence Test – a finding supported by a recent, more rigorous study, published in JAMA Network Open in 2022.

Scientists at the University of Vermont looked at data from nearly 2,000 children and found that those who reported playing fast-paced video games for three hours a day or more did better on tests of impulse control and working memory than children who said they never played video games. .

Not only that, but brain scans showed they had greater activity in areas related to attention and memory, the result of all those hours spent photographing things and avoiding being shot.

And last but not least, keep challenging yourself mentally. There is plenty of evidence that taking up new hobbies, such as dancing or painting, will keep your brain young.

Conversely, withdrawing from the world can lead to brain shrinkage, decreased brain cell connections, and even declining levels of hormones in the brain that are essential for long-term recovery and maintenance.

I plan to do what I can to keep my neurons firing as long as possible and, as poet Dylan Thomas put it, to “rage, rage against the dying of the light.”

One of the most difficult things to treat is a chronic wound, such as that caused by type 2 diabetes.

Now researchers at Sheffield University are using ionized gas (gas with an electrical charge) to treat chronic wounds: the gas creates a chemical cocktail in the wound, killing bacteria and speeding up healing. With antibiotic resistance on the rise, this could be a game changer.

Your dog really understands

Our dog, Tari, passed away a few months ago, and I still shout “walkies” as I walk to the front door, forgetting that she is no longer there.

I’ve often wondered if she understood the word “walkies,” or if it was my tone and behavior (i.e. the fact that I was standing at the front door with a leash in my hand) that gave her the clue.

A recent study shows that dogs understand us better than we think. Researchers at Eotvos Lorand University in Budapest monitored the brain waves of dogs when they heard their owners say words they thought the dogs knew, such as “ball.”

They found that when the dogs were given a toy that matched the word their owner said, their brain activity was different than when they were given something that did not match it.

The researchers said this is proof that dogs actually understand the meaning of words. Our canine friends are even more remarkable than most of us already believe.

Bitter-tasting vegetables can boost your mood

Many people have difficulty eating bitter green vegetables such as kale, Swiss chard and chicory. Yet these are extremely good for us – and you can read more about why here.

Bitterness is one of our five ‘basic’ tastes (the others are sweet, salty, sour and umami). Humans are particularly sensitive to bitter tastes, probably because bitterness in nature is often associated with poison, something that should be avoided.

Yet bitterness is also a sign that food is rich in beneficial plant compounds called polyphenols. Recent research by the Shibaura Institute of Technology in Japan has provided fascinating insights into why polyphenols are so good for us.

They point out that we have taste receptors throughout our bodies. For example, they are found in the intestines, where they respond to polyphenols you have eaten by releasing hormones that improve your blood sugar levels and your mood.

Men even have similar sensory receptors in the testicles that appear to play a role in the production of healthy sperm. That could explain why men who eat lots of bitter, green leafy vegetables tend to have higher sperm counts and better sperm motility.

Something to keep in mind the next time you go shopping for vegetables.