The human brain reaches adult size by the age of 10; but its wiring and its abilities continue to change through a lifetime.
After the age of 40, the brain begins to shrink in volume. Less blood flows through the brain, and hormone and neurotransmitter levels go down. Ageing leads to slowing down in some functions such as the learning of new tasks.
Learning requires the formation of new connections in the brain, a property called neuroplasticity. Your brain is a dynamic entity that is constantly remodelling itself in response to new experiences.
Some brain structures show greater plasticity and rewiring than others. Ageing affects them more extensively than others. One such structure is the hippocampus. Located between the ears, it plays a key role in the formation and consolidation of new and lasting memories, and thus of learning and experience. It also creates mental maps of your surroundings, enabling you to find your way home.
Experiments have shown that the brains of older mice have fewer connections, called synapses, between their nerve cells and perform poorly in finding their way through mazes — indicating deficiencies in spatial learning.
MRI studies on the brains of London taxi drivers show that they have an enlarged hippocampus — the city’s roads have been ‘mapped’ in the hippocampus, and this ‘map’ readily expands as experience is gained.
Human studies in this area, however, are confounded by large differences between individuals — some “Super Agers” can even compete with much younger people in memory tests.
Brain injuries
The brain’s capacity for rewiring and change is seen in the case of brain injuries resulting from trauma or from a stroke. A large number of brain cells die in such events, leading to a loss of some abilities. Yet over time, the brain remodels itself, leading to a full or partial restoration of lost abilities. This can be accelerated by medications, stem cell therapy and psychological interventions.
The aging process is often, but not always, accompanied by cognitive decline. Along with memory, executive functions may be impaired — these include the ability to plan and the ability to perform two or more tasks simultaneously.
These changes are a consequence of a reduced ability of the brain to rewire itself, of reduced neuroplasticity. But it is possible to change behavioral and lifestyle patterns to enhance the brain’s ability to adapt, and to function like a younger brain.
Regular exercise and sensible dietary choices are key elements in keeping your brain young, as is an aptitude for learning (mastering a new language, or musical instrument).
Benefits of exercise
In aging individuals, exercise reduces the risk from systemic disorders such as heart ailments and high blood pressure. Such disorders elevate the risk of dementia. Thus, exercise reduces the risk of dementia and debilitating conditions such as Alzheimer’s disease.
Regular exercise also helps you lose weight or at least stop gaining weight or regaining lost weight. The probability of occurrence of cancers of the lung, stomach, colon and bladder is lowered. Exercising individuals are less prone to anxiety and depression.
A significant benefit of exercise in older adults is the lowered risk of falls, and of fall-related injuries. Exercise enhances the stability of your posture, both while standing and when you are in motion, as your brain is being trained over and over to quickly respond to disturbances in your balance (Rogge et al., Neuropsychologia, 2019).
What type of exercise is better? Comparing the results from six months of aerobic endurance training (cycling indoors) with stretching/coordination training show us that in the 40-56 age group, both these activities lead to improvement in memory relative to sedentary individuals. These activities will of course improve cardiovascular fitness, and participants in the study, who showed the most improvement in their cardiovascular fitness, also had the best improvements in memory. Reverting to lethargy and lowering one’s fitness level negates the gains in memory functions (Hötting and Röder, Neurosci. Behav. Rev, 2013).
Cognitive training, meaning exercising your brain, helps your brain to stay flexible. Combining this with physical exercise shows even better results in improving the cognitive abilities of older people.
The amount of exercise required is another question that older people may worry about. Health and cognitive parameters in older individuals are often evaluated before and after a 10-minute routine involving some jogging and some walking, “enough to cause a mild sweat but not cause fatigue”. For those above 65, the World Health Organization (WHO) recommends 30 minutes of brisk walking five or more times a week.
Get in touch with the author at dbala@lvpei.org.
