[Editor's note: Science writer Jude Isabella recently attended the American Association for the Advancement of Science annual conference in Chicago, and her dispatches are running on The Tyee this week. Stay tuned for more.]
To live a dementia-free life, exercise, have at least one friend, live an interesting life, don't fret, and bring your library books back on time.
Well, it's not so much about bringing the books back on time as showing conscientiousness, and conscientiousness is good for your brain. Although if you're neurotic and fret about bringing your books back on time, that's probably bad for your brain.
It's a complex road to resilient aging, and what each of us wants to know is the key to growing old without losing too many marbles. "It's not likely to reside in any one elixir," said Elizabeth Stine-Morrow, a psychologist at University of Illinois, Urbana-Champaign. "There's a lot of snake oil out there."
That whole idea of brushing your teeth with your left hand if you're right-handed? And vice versa? There's no evidence that increases cognition. You can, however, drink in moderation, maybe even smoke, and have fun (with other people). Phew.
Brain health is a pressing public health concern. A century ago, four to five per cent of people in North America were over age 65. Now it's up to one-fifth of the population in some areas. (In 2011, the proportion of seniors in Canada was among the lowest of the G8 countries.)
No matter how hard they try, at least when it comes to brain health, Baby Boomers will never turn 70 into the new 20. But some of the most recent science behind resilient aging, presented at last weekend's American Association for the Advancement of Science conference in Chicago, offers a few hopeful, practical suggestions for delaying dementia as long as possible.
Call in the reserves
So, where to start? First, build up your brain reserves, said Yaakov Stern from Columbia University.
"We know that specific changes in the brain that are responsible for Alzheimer's probably occur 20 or 30 years before someone experiences symptoms," Stern said. "Clinical symptoms appear later if you have more reserves, sooner if you have little reserves."
Brain reserves accumulate over a lifetime of experiences, and there are a few ways to boost them. It's good to get an education earlier in life, for example. Low levels of education double the risk of Alzheimer's.
"It's not that education prevents Alzheimer's, but it allows people to cope with the dementia process better and for longer before they succumb," Stern said.
Stern's results come from the Washington Heights-Inwood Columbia Aging Project (WHICAP). The effects of formal education are the easiest to measure, but Stern said other, informal education is probably equally as effective in warding off symptoms.
The other two ways to build reserves are through your mid-life occupation and your leisure activities later in life. If you spend eight hours a day sorting coatroom checks in a factory (one of my winter break jobs while at university), you're likely not building up brain reserves. As for leisure, people who engaged in more relaxing, fun activities later in life had half the risk of Alzheimer's.
Even though everyone's brain shrinks as they age, people with higher reserves tolerate volume loss, Stern concluded. "I think that people with reserves have more efficient networks, more resilient networks, [and] alternative ways of doing tasks to allow them to function," he said.
In other words, education, a stimulating job, and the leisure time to pursue an interesting life translate into more efficient brain networks, leading to resilience. "Reserves are not something you're born with," Stern says. "[They're] influenced by every stage of life."
Since a person's socioeconomic status influences all three of these reserve-builders, it might be a good idea for governments to invest in education, a diversified economy, and to promote a 32-hour work week.
In fact, we even know the cost of not investing in brain reserves -- Americans spent $172 billion on the care and treatment of Alzheimer's patients in 2010, and that number is projected to be over $1 trillion by 2050. The Alzheimer's Society of Canada believes that by 2040, Canada will spend $293 billion on Alzheimer's patients each year.
There is something a person can do on an individual level, though: exercise.
Kirk Erickson at the University of Pittsburgh studies how the brain responds to exercise, particularly the hippocampus, critical for memory formation and a part of the brain that shrinks considerably with Alzheimer's. Wonder where it is? Put your fingers in your ears (not too far -- every other doctor says to put nothing smaller than an elbow in your ear) and you're basically pointing at your hippocampus.
Erickson conducts brain intervention research, and after in-depth study he's certain that inactivity is a big risk factor for dementia.
First, researchers looked at rodents. Exercise a rat, and its hippocampus stays robust. No exercise, and its hippocampus atrophies. In humans, researchers have looked at fitness (measured in lung capacity), and over the years the results have become irrefutable -- whether old or young, the fitter you are, the larger your hippocampal volumes. But unlike brain reserves, at any age exercise can alter the hippocampal volume.
Erickson's lab brought in 120 older sedentary adults and randomly placed them in either a brisk walking group, or a stretching and toning group. They came into the lab three days a week and walked for 30 to 40 minutes at a time, getting their heart rate up. The stretching was a non-aerobic activity. (Attendance was 80 per cent, considered very good for a study.) After only a year of exercise, researchers saw a significant increase in the hippocampus of the group that walked.
"This shows plasticity in older adult brains," Erickson said. The hippocampus was easily modified with the modest exercise regime. "I still know of no pharmaceutical treatment that can demonstrate the same effect."
Take that, Big Pharma.
Aside from the startling effect on the hippocampus, exercise increases the brain's white matter, important for connections, and it positively affects the pre-frontal cortex, where the brain's executive functions lie.
Now, what about people who show less improvement with exercise or take longer to improve compared with others? Do they just have the wrong genes? We can't fight our genes, can we? Well, yes, we can.
Erickson took on the gene question by looking at what's called the BDNF gene, which produces a molecule also called BDNF. It is critical in long term memory function, of which gobs are found in the hippocampus. (Alzheimer's patients have less BDNF in many regions of the brain compared to those without Alzheimer's.) The gene is polymorphic, meaning you have a couple of versions, and Erickson wondered if this polymorphism moderates the effect of exercise.
Studies of rodents have shown that exercise increases the expression of BDNF. Erickson's research looked at 1,000 people -- those who were genetically at risk and those who were not. Those at risk were only at risk if they didn't exercise. Turns out, physical activity trumps the effect of genes on memory performance.
The takeaway? Exercise is great for brain health, but you don't have to run marathons to see the effects. "There's only so much room to grow," Erickson said. "There must be some plateau where brains no longer respond to exercise."
Take time for a challenge
Exercise is undeniably good for brain health, and so are cognitive challenges. Ulman Lindenberger, director of the Center for Lifespan Psychology at the Max Planck Institute for Human Development, is interested in cognitive plasticity in adulthood.
"With advancing age, people get more and more dissimilar as to how much decline they show," Lindenberger said. "So individual differences in aging increase with age. You have some older adults who are top performers, and we all want to know how they ended up there."
Lindenberger's idea is that when people consistently put themselves in a situation where their cognitive demand is bigger than their cognitive supply, the tension creates a need for plasticity and the brain begins to change, provided it has the biological potential to do so.
"Think of plasticity as a dynamic interplay, with the demands of the situation on one hand, and the supply on the other," he said. It's a mismatch of supply-demand, but the mismatch must be within reach of the person, i.e. studying black holes with Stephen Hawking might be out of reach for some of us.
Lindenberger and his colleagues turned to a couple of studies (COGITO and SPACE) to investigate the malleability of the adult brain.
In the COGITO study, 101 people (aged 20 to 31) and 103 people (aged 65 to 80) visited the lab two to three times a week and performed 12 cognitive tasks for one to 1.5 hours, for a total of 100 training sessions. The tasks focused on perceptual speed, working memory, and episodic memory; it was like a cognitive exercise regime. At the brain level, researchers noticed an improvement in white matter integrity and less pronounced shrinkage in the cerebellum of people who took the cognitive training compared with an untrained group. They also found that younger people in the training group showed general improvements in working memory, reasoning and episodic memory. Older adults only improved in working memory.
In the SPACE study, researchers looked at the hippocampus by putting 23 younger and 23 older participants on a treadmill and having them spatially navigate a virtual zoo, looking for animals in 50-minute sessions, 42 times. No surprise -- the combined activity attenuated age-related shrinkage of the hippocampus. Adult brains have plastic potential, and plasticity contributes to resilience in cognitive aging.
Note the SPACE study combined intellectual and physical activity -- the idea behind it being that evolutionarily we spent a lot of time walking around, orienting ourselves in the world, avoiding the stuff that could hurt us (a poisonous snake?), and training ourselves to notice the good things (such as where we might find water).
Sharing good times
Okay, we're not done yet. Turns out, personality and loneliness can also influence someone's chances of developing dementia.
Daniel K. Mroczek at Northwestern University studies personality traits and how they affect mortality, concentrating on conscientiousness and neuroticism (in other words, self control and emotional stability). If you have self-control, you're more likely to do things like eat right, drink moderately, exercise, and save money for retirement. If you're emotionally stable, you don't overreact to stress. (And if you're an astronaut or test pilot, you don't react emotionally at all.)
Neuroticism does, and can, change over time. In a 2007 study looking at over 1,500 people, those who maintained a high level of neurosis died earlier than those who were more emotionally stable or became more emotionally stable as they aged. In another study of 181 men, published in the Dec. 2013 issue of Gerontology, interventions in emotional stability (training people to avoid overreacting) showed improved immune function and an increase in brain regions that promote positive effects.
"Dynamic aspects of personality, whether macro (long term) or micro (over days), are both part of [brain] resilience," Mroczek said.
So go ahead, make fun of the West Coast's preoccupation with mindfulness, but it's a good way to lessen neuroticism.
Finally, loneliness. John Cacioppo, director of the Center for Cognitive and Social Neuroscience at the University of Chicago, studies the effects of social connections on people.
"Interacting with others is one of most enjoyable daily activities people engage in," he said, adding that the type of interaction matters. "Obligatory interaction, like dealing with bosses, is as unpleasant as spending time alone."
The Chicago Health, Aging and Social Relationship study has confirmed that feelings of loneliness (perceived isolation) increase the risk of depression, affecting well-being in the long term.
"Social isolation -- of being on the social perimeter -- is not only unhappy, it is dangerous," Cacioppo said. "For instance, fish on the edge of a group are more likely to be attacked by predatory fish, not because they are the slowest or weakest, but because it is easier to isolate and prey upon those on the social perimeter. The behavioural expression of self-preservation when on the social perimeter by fish illustrates a more general principle, specifically, that the brain's perception of social isolation activates neural, neuroendocrine, and behavioural responses that promote short-term self-preservation."
In the biological pathways of people who feel socially isolated, researchers have seen an increase in cortisol (the stress hormone), altered gene expression, and a decrease in inflammation control, which leads to decreased immune function.
So loneliness can be a predictor of who gets dementia. The good news? It's the quality of our social connections that makes a difference. Having even one friend hugely improves health outcomes, Cacioppo said. "It's very under-appreciated, sharing good times," he added.
Wait, what about smoking?!
One more thing: you're dying to know about smoking, right? Isn't it bad?
It's not so much smoking, but the nicotine that can be helpful in warding off dementia. And that's true of other drugs of abuse, like coffee, which can lead to certain increases in cerebral function (although if you smoke you're more likely to die before reaching an age for dementia to set in).
But that's a story for another day.