an autodidact meets a dilettante…

I read recently that regular moderate exercise sloshes up the blood, washing immune cells from vessel walls. This brings those cells back into the mainstream so to speak, where they can be more effective in combating infection. It makes no small difference – a simple study in which 500 adults were tracked for 12 weeks found that those who engaged in regular aerobic exercise sessions were found to suffer considerably less from upper respiratory tract infections – precisely my personal area of concern. Levels of immune cells in the blood double during exercise.

There’s also good news in this for those of us who couldn’t become gym junkies no matter how hard we tried. Too much exercise (but that means quite a lot) can undo all the good by raising levels of cortisol, noradrenaline and other stress hormones, which alter immune cell functioning. Stress, though, is another one of those complex indicators of health. Mild bouts of stress can be healthful, again boosting blood levels of immune cells. So don’t relax too much, but don’t overdo it.

Even so, exercise helps with everything, and that’s something worth promoting because the recommended dose of exercise isn’t being swallowed by the majority of people in the west. Of course we’ve always kind of known about the benefits of exercise, but the hard evidence has really been coming in lately. A really interesting study was published in the Lancet in 1953, at a time when the rising incidence of heart attacks was becoming a worry. It compared bus conductors to bus drivers on London’s busy double-deckers. The conductors, who spent much of their working day running up and down steps, had half as many heart attacks as their driver colleagues. This landmark study has of course been followed by many others that have confirmed the positive effects of exercise in reducing the incidence of stroke, cancer, diabetes, liver and kidney disease, osteoporosis, dementia and d barkepression.

So what exactly is the goldilocks zone for exercise? Well, anything is better than nothing, and most of us know we’re not doing enough. I’m not quite a senior citizen yet, but studies have been done with the elderly requiring them to do 40 minute walks three times a week, which is hardly strenuous. I catch a tram to work, which requires a ten-minute walk each way, and then a five minute walk each way to my workplace – 30 minutes a day, five days a week, though it would doubtless be better if those 30 minutes were continuous, and if I didn’t dawdle much of the time. The benefits of such a regime have been shown through before-and-after brain imaging. Expansion of the hippocampi, either through the growth of new brain cells, or greater synaptic connectivity, and a restoration of long-distance connections across the brain.

Mental exercise shouldn’t be forgotten either. It has been known for a couple of decades that intellectual stimulation can provide a kind of ‘cognitive reserve’ which can buffer us against the kinds of physical brain deterioration typical of Alzheimer’s and other forms of dementia, but clearer proofs of this have been gathered recently. Magnetic resonance imaging of Alzheimer’s sufferers has caught the goings-on in the brain while cognitive tasks are being performed. Highly educated people – brain workers  if you will – are better able to develop alternative neuronal networks to compensate for damaged areas. I would assume though that it’s not so much about education but about brain usage. Keep tackling new things. Keep using your brain in new ways. And your body for that matter.

Cognitive reserve is now seen as a real thing, and has been pinpointed as residing in the dorsolateral prefrontal cortex, a key area for learning, short term memory, attention and language. Increased activity in this area suggests flexibility in thinking and problem solving. Information processing efficiency is also a key to a healthy brain. Having a high IQ, something I’ve often been sceptical about in the past, is an indication of information processing efficiency, even if the information is often culturally specific. It appears that physical brain deterioration, from Alzheimer’s, stroke and and other causes, can be fended off by compensating neural network development and increased information processing efficiency in certain people, until the deterioration becomes too great to be compensated for, after which things tend to go downhill very rapidly. By the time the symptoms of Alzheimer’s appear in such people, the  physical damage is already well advanced.

A major message from all this is that you should try to develop lifestyle habits involving physical and mental exercise. Always a work in progress.

I note that one of the in terms these days is ‘hat tip’ (h/t), so h/t for this piece to New Scientist, the collection, edition 3: a guide to a better you.