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The Five Ages of the Brain: Old Age
By Helen Thomson, newscientist.com
April
6, 2009
Not everyone ages in the same way, but what's the difference between a jolly, intelligent oldie and a forgetful, grumpy granny? (Image: LaCoppola-Meier / Photonica / Getty)
Down but not out
By the time you retire, there's no doubt about it, your brain isn't what it used to be. By 65 most people will start to notice the signs: you forget people's names and the teapot occasionally turns up in the fridge.
There is a good reason why our memories start to let us down. At this stage of life we are steadily losing brain cells in critical areas such as the hippocampus - the area where memories are processed. This is not too much of a problem at first; even in old age the brain is flexible enough to compensate. At some point though, the losses start to make themselves felt.
Clearly not everyone ages in the same way, so what's the difference between a jolly, intelligent oldie and a forgetful, grumpy granny? And can we improve our chances of becoming the former?
Exercise can certainly help. Numerous studies have shown that gentle exercise three times a week can improve concentration and abstract reasoning in older people, perhaps by stimulating the growth of new brain cells. Exercise also helps steady our blood glucose. As we age, our glucose regulation worsens, which causes spikes in blood sugar. This can affect the dentate gyrus, an area within the hippocampus that helps form memories. Since physical activity helps regulate glucose, getting out and about could reduce these peaks and, potentially, improve your memory (Annals of Neurology, vol 64, p 698).
Coordination training could also help. Studies have shown that specifically targeting motor control and balance improves cognitive function in 60 to 80-year-olds. A few sessions on the grandchildren's Nintendo Wii could bring similar benefits.
If you're struggling to find the guitar hero in yourself, however, try a cognitive workout instead. "Brain training" was once considered flaky, but a study due to be published in the Journal of the American Geriatrics Society in April concludes that computerised brain exercises can improve memory and attention in the over 65s. Importantly, these changes were large enough that participants reported significant improvements in everyday activities, such as remembering names or following conversations in noisy restaurants.
Avoiding the grumps is even easier. Dopamine receptors - responsible for feelings of positive emotions - are in decline, with the potential to cause depression, but you can give yourself a regular dose of dopamine by eating certain foods, such as yoghurt, almonds and chocolate.
In fact, your brain is doing it all it can to ensure a contented retirement. During the escapades of your 20s and 30s and the trials of midlife, it has been quietly learning how to focus on the good things in life. By 65 we are much better at maximising the experience of positive emotion, says Florin Dolcos, a neurobiologist at the University of Alberta in Canada. In experiments, he found that people over the age of 60 tended to remember fewer emotionally negative photographs compared with positive or neutral ones than younger people (Psychological Science, vol 20, p 74).
When I was young...
MRI scans showed why. While the over-60s showed normal activation in the amygdala, a region of the brain that processes emotion, its interaction with other brain areas differed: it interacted less with the hippocampus than in younger people and more with the dorsolateral frontal cortex, a region involved in controlling emotions. Dolcos suggests that this may be a result of more experience of situations in which emotional responses need to be kept under control. Older people really do see the world through rose-tinted glasses.
So while nobody wants to get older, it's not all doom and gloom. In fact you should probably stop worrying altogether. Studies show that people who are more laid back are less likely to develop dementia than stress bunnies. In one study, people who were socially inactive but calm had a 50 per cent lower risk of developing dementia compared with those who were isolated and prone to distress (Neurology, vol 72, p 253). This is likely to be caused by stress-induced high levels of cortisol, which may cause shrinkage in the anterior cingulate cortex, an area linked to Alzheimer's disease and depression in older people.
So while our brains may not wrinkle and sag like our skin, they need just as much care and attention - so don't give up on yours too soon. When you notice the signs of age, go for a walk, do a crossword and try to have a laugh - it might just counteract some of the sins of your youth.
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