The Aging Brain: Brain Changes During Healthy Aging

by Ram

Self Portrait by Joan Miro *

I have written several articles in the past regarding the brain, brain pathology, the mind, and mental exercise. Much of that focused on the brain in a pathological setting in addition to modalities necessary to improve and strengthen the brain and mind including yoga, meditation, and pranayama. But an important question is: what happens to the brain during healthy aging? Do we know the changes in the structure and function of the brain as the individual ages without any underlying neuro-pathological condition? Actually, there are a number of laboratories that are focusing on brain changes during aging with hopes that this would lead to a better understanding of brain function during a pathological condition. Most of the evidence has come from magnetic resonance imaging (MRI) studies of age-related changes in brain. Thus far we know the following:

1. As a person ages, certain areas of the brain, including the prefrontal cortex (an area that covers the front part of the frontal lobe) and the hippocampus, shrink to size. Thus, the functions attributed to these two areas, namely, learning, memory acquisition and recall, planning, cognitive behavior, personality, social behavior and decision making, all are compromised as the person ages.
2. Shrinkage of the brain is associated with a concomitant increase in the ventricular space (the ventricles are cavities surrounding the brain region where the cerebrospinal fluid (CSF) is produced).
3. The cortical thickness is reduced by 0.5% and 1.0% in most brain areas.
4. The volumetric brain reduction is also associated with shrinkage of neurons, reductions of synaptic spine density and total synapses. There is a general reduction in white matter (myelin covered axons) due to neuronal death. This affects the communication between neurons resulting in reduced function.
5. Blood flow to the brain reduces with age because the arteries shrink and there is also reduction in the growth of new capillaries.
6. In some people, structures called plaques and tangles accumulate inside and outside of the brain that disrupt the communication network between neurons.
7. Aging also triggers the production of free radicals. Free radicals have a tendency to interact with cellular structures and cause their destruction.
8. The presence of plaques, tangles, and free radicals triggers inflammation. If inflammation goes unchecked, it can elicit several brain disorders.

What about mental function in healthy older people? Due to changes in the physical structures of the brain, mental capacity and functions also change. Generally people complain about a decline in mental ability, including learning new things, recalling/retrieving information, and keeping up with latest technological advances. Aged individuals will also perform poorly on complex tasks of attention, learning, and memory. In contrast, if these individuals are made to practice the same tasks, their scores are often similar to those of young adults. Furthermore, as they age, adults often show improvement in other cognitive tasks, including vocabulary, verbal knowledge, and information analysis. This may be due to the compensatory mechanisms unfolded by the brain to cope with difficulties that certain regions may be having.

While it is obvious that there may be a general decline in mental abilities, more recent evidence points out to the adaptive functions of the brain aka brain plasticity (see The Power of Mental Exercise) as people age. Learning/stimulating environments maintain, build, and remodel neural network connectivity and also trigger production of nerve growth factors that stimulate new neural connections (see How Yoga Sequences Are Brain Aerobics). The brain actively grows and rewires itself in response to stimulation and learning (see Svadhyaya, Reading, and Brain Strength). Other stimulating factors include lifestyle, environment, and genetics. 

Furthermore, the concept of cognitive reserve is being investigated to explain why some people remain cognitively healthy as they get older while others develop cognitive impairment. Cognitive reserve refers to: 1) the brain’s ability to function smoothly even when some function is disrupted and 2) the extent of brain damage required before changes in cognition are evident. Individuals differ in their cognitive reserve capacity owing to genes, education, occupation, lifestyle, or other life experiences, all of which provide immense resistance to deleterious changes and damage in the brain that occurs during aging. 

A list of lifestyle changes that older adults can implement to preserve healthy brain aging and an overall good health include:

• Controlling risk factors for heart disease, diabetes and obesity
• Maintaining a normal range of cholesterol
• Maintaining blood pressure at healthy levels
• Maintaining a healthy weight
• Getting a good night & refreshing sleep
• Enjoying regular exercise and physical activity
• Low to moderate consumption of sugary foods
• Eating a healthy diet that includes plenty of vegetables and fruits
• Engaging in intellectually stimulating activities
• Maintaining good social ties with family and friends

As discussed in previous posts (Mental Exercise, Yoga, and the Perfect Brain), a steady practice of yoga, meditation, pranayama, and cognitive exercises work beautifully as part of the preventive strategies. All the previous posts advocated incorporating some form of yoga on a daily basis that could not only add new life to the dull and routine tasks of everyday life but also keep the brain fit physically, mentally and emotionally.

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