Brain Fitness and "Cognitive Reserve"

Over the years physicians have developed a wide variety of techniques for assessing a person's physical fitness. For example, if you have a medical your heart rate, blood pressure, cholesterol level, weight and height will all be measured and both your blood and urine will be screened for possible diseases. In fact, your whole body will be checked with the notable exception being your brain.

The reason peoples' brains are omitted from medical examination is because no one has yet come up with a reliable means of assessing the health of a brain, but that may be about to change.

In recent years scientists have been investigating a phenomenon known as "cognitive reserve". In simple terms, a person's cognitive reserve is the density of connections between the neurons in the brain. The theory is that the greater the density, the more resistant the brain is to degenerative conditions such as Alzheimer's. For example, suppose you have just one neural connection between two important cells in the brain and a degenerative disease causes that link to fail. The link will therefore be broken and whatever functions relied on that connection will be lost. However, if the same person had two or more connections between those cells, it would take much longer for the disease to sever all the connections and cause the same amount of damage.

In the same way as being physically fit does not make you immune from illness but will reduce both the likelihood of becoming ill and its severity, cognitive reserve can improve a person's resistance to neurological disorders. It can therefore be thought of as a measure of brain fitness.

The obvious next question must be; how can we improve our cognitive reserve?

Dr Joe Verghese at the Albert Einstein College of Medicine in New York was interested in the impact of the physical and mental lifestyle choices made in the over 75 age group. Over 5 years he conducted a study on 469 people, none of whom showed any signs of brain degeneration or dementia at the outset. 5 years later, more than a quarter had developed dementia. This lifestyle research showed an interesting link between mental activity and the disease - those people that exercised their brains with challenging and varied tasks were less likely to develop the disease. Interestingly it appeared that no one mental activity was better than others, but rather that it was the variety of activities that was important.

Known as the doctor who gave meaning to the phrase "use it or lose it" regarding our brains, Dr Verghese's studies offered support to the cognitive reserve theory - by being involved in varied mental activities, the brain builds a buffer (or reserve) in the brain by increasing the connections between cells and promoting cell growth. While this did not decrease the likelihood of a person developing dementia, it did appear to delay the impact of the condition and make them more resistant to its effects.

It is interesting that the study did not find any correlation between a person's physical fitness and their cognitive reserve. It therefore appears that while exercise can improve both our physical and mental wellbeing, it appears to do nothing for the brain, which instead relies exclusively on diet and mental exercise to remain fit and well.

Published January 2011

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