I’ve been reading John Medina’s book Brain Rules for Aging Well. Medina, a molecular biologist, presents his guiding principles for healthy aging. He writes with the scientific rigour you would expect from a scientist. At the same time, Brain Rules for Aging Well is an enjoyable, reader-friendly book. Having worked my way through it, I feel more informed about what truly contributes to healthy aging. Here are a couple of my new insights.
Medina has set me straight about multi-tasking. He says: “Scientists have known for years that true multitasking is a myth. It’s impossible for any brain to monitor two attention-rich targets simultaneously. The only way your brain can track multiple targets is to use a task-switching strategy (p.116.)”
I’d always known that the aging brain, unlike younger brains, is incapable of doing two things at once. Witness the older person trying to carry on a conversation while writing a note to a friend. Younger people can do both at once. I had always attributed this to the aging brains’ inability to multi-task. Medina sets the record straight.
“Older folks concentrate on tasks just as well as younger ones, maybe even better. What’s at stake here is the increasing inability to ignore distractions. This is what makes it hard for the older person to manage two tasks at once (p. 225.)” He continues: “Our ability to ignore distractions declines from a high of 82 per cent when younger to a low of 56 per cent when older.” Scientists call this ‘divided attention,’ not ‘multi-tasking.’ It’s the increasing inability to ignore distractions (p. 115.) It simply gets harder for us to switch between tasks with age (p.115.) After all, Medina points out, we’re living in a body that was never built to handle life past thirty.
Then there’s the matter of cortisol, the steroid hormone that’s released when we’re stressed. Too much cortisol damages the brain.
“When too much cortisol hangs around too long, it can actually whittle away at hippocampal tissue, causing the organ to atrophy (p. 71.)” You will remember that the hippocampus is responsible for our memory. What older person isn’t worried about memory loss?
The bad news gets worse. As we age, we don’t calm down as quickly as we once did. That means an even greater release of cortisol.
Medina explains that this steroid hormone was meant to help the body respond to stress. That was all very well for animals or for our primitive ancestors. Their stressors were short lived. Either you managed to run faster than the tiger, or you were eaten and that was the end of it. The problem is, for us humans, stressors are usually complex, about relationships or money: not issues that are over quickly. We end up with too much cortisol in our systems and this damages parts of the brain, especially the hippocampus.
At this point I shiver with fear. Old age itself is stressful, even if your life runs smoothly. Considering my own life path and the rough road I’ve been travelling, I figure I’m doomed to memory loss. I shudder to think how much cortisol my own body’s fight-or-flight response has been dumping on my hippocampus. After all, in the past three years I’ve left a marriage after 55 years, moved four times, got really sick in Arizona and now am concentrating on recovering in a retirement home until I’m well enough to get my own apartment again.
But wait! There’s hope, says Medina. The hippocampus is capable of making new neural tissue if you practice of mindfulness. Mindfulness is about cultivating the habit of paying close attention to any task we’re carrying out and staying very present to our surroundings. If I learn to practice this, I’ll not only stay calm, I’ll give my hippocampus a chance to hold more memory.
In my next post, I’ll let you know how I’m making out with my new practice of mindfulness.