As we progress through life we inevitably find ourselves becoming increasingly forgetful. It is not as if bouts of forgetfulness never occurred when we were younger. It’s just that it begins to happen more and more frequently – to the point where it becomes much more noticeable; even troublesome . From our mid-twenties onwards we lose more neurons (brain wires) and synapses (connections between the brain wires) than we build. The long term end point of this perfectly natural, gradual process of brain aging is dementia. By which I mean if we all lived to the impossibly grand old age of 200, every single one of us would have developed dementia of one description or another along the way. In reality very few of us will even make it to the grand old age of 100, let alone 200. Of those that do, not everyone will have become plunged into the amnesic fog of dementia. So what is the difference between individuals that do and don’t develop dementia well into their senior years? Is it blind luck? Or is there something we can do to lengthen our dementia-free status?
In the past I have written about the importance of exercise for brain health. This is largely to do with ensuring efficient blood flow. Exercise makes the heart strong, better able to keep the blood pumping to every corner of the brain throughout every day and night. There’s no room for storage in the brain so it requires a constant supply of oxygen, glucose and nutrients in the blood or the brain cells will function less efficiently and, after just a few minutes of interruption to blood flow, even die. Both smoking and a high fat diet narrow the blood vessels of the body and brain. They also makes the walls of the arteries more rigid. Not only does this reduce their capacity for carrying blood, they are also less able to snap back into place after each pulse subsides. In healthy young arteries with good elasticity this enables blood to be shunted along more efficiently. Indeed, a recent study demonstrated that smoking and being overweight has a negative impact upon cognitive abilities; causing a significant decrease in performance. So exercising regularly, quitting smoking and reducing the intake of saturated fats all help to slow age-related cognitive decline by limiting the contribution of decreases in efficiency of delivering blood to the brain at all times.
I have also described in the past how many minor illnesses or a few major surgeries can accelerate descent into dementia by cranking up the immune system. So being vigilant in terms of good hygiene to avoid minor illnesses and foregoing surgery unless absolutely necessary are also wise steps for delaying descent into dementia. In this piece I would like to revisit the concept of cognitive reserve in light of lots of new research suggesting that some of the latest brain training software can be particularly effective when it comes to helping the aging brain develop a resistance to age-related cognitive decline.
Michael Merzenich is an outstanding neuroscientist who has made a significant contribution to our understanding of the brain. Decades of his research have produced a sturdy foundation upon which the concept of neuroplasticity has been built. Neuroplasticity is the brain’s ability to adapt to the demands placed on it by complex interactions with our environment. He has become one of the foremost pioneers in producing and testing brain training computer software in terms of its ability to improve the cognitive abilities of older brains. The major difference between his approach and that of other brain training games produced by the likes of Nintendo and Lumosity is that his company, Posit Science, have formally tested their brain training games in several, scientifically-rigorous, peer-reviewed, clinical trials such as the IMPACT, ACTIVE and IHAMS studies.
Brain training essentially involves simple computer games designed to challenge brain areas involved in creating and retrieving memories, solving problems, improving visual and auditory perception, and sustaining attention for long enough to complete a complex series of cognitive tasks. The ultimate aim is not just to get better at the specific games, but for the improvements to extend to cognitive functions that are useful in everyday life. For instance, the 487 older people who participated in the IMPACT study found that they had an improved ability to remember items of a shopping list that had not been written down, their auditory acuity improved to the point that they were better able to hear what people were saying in a noisy environment and that they found it easier to bring words to mind during conversations. The overarching principle of brain training is that by regularly (ideally daily sittings), intensively (for prolonged periods of time in any one sitting) and consistently (keeping up training over many weeks and months) exercising brain areas involved in executing these mental processes the connectivity between them will be bolstered by creating new synaptic connections. The increase in interconnectivity between different brain areas improves cognitive functions required by the various exercises thus improving these abilities.
The inspiration for increasing interconnectivity in the brain comes from observations that some people can have severe damage done to their brain by the metabolic waste materials that clog up neurons as a result of Alzheimer’s disease yet exhibit no signs of Alzheimer’s dementia. In other words they may have the brain damage from the disease but not the behavioural symptoms of dementia. The people that have the damage but no apparent symptoms tend to be better educated. The current explanation for how this might be possible is that better educated people are likely to have increased connectivity within and between their neuronal networks that resulted from sustained mental effort involved in an education that lasts for many rather than a few years. This additional connectivity is thought to enable other brain areas to collectively take over the roles and responsibilities of brain areas damaged by the metabolic disease. Hence their daily behaviours are not noticeably affected to the same degree as someone with lesser lifestyle induced connectivity and a consequent poorer capacity to compensate for the damaged brain areas.
The aim with a combination of education about lifestyle choices that help keep the brain healthy well into old age in combination with a wide variety of rigorous brain training exercises adhered to over several years might help everyone, irrespective of educational attainment, develop cognitive reserve. By increasing interconnectivity between different brain areas involved in a wide variety of cognitive functions the onset of dementia may be delayed by enabling other brain areas take over the function of regions damaged by the natural metabolic processes of brain aging.
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