Brain Reserve

“Brain reserve” refers to the physical amount of brain we have available and includes the actual size and thickness of your brain, the number of brain cells (also called neurons), and the number of connections that exists between those neurons (called synapses). How our brain is structured impacts how our brains respond in the face of damage (e.g., from dementia, car accident, stroke, etc.) Research has shown that people that experience damage to the same area of the brain exhibit symptoms in a different way. This difference in how our brains respond to damage is attributed to our “brain reserve”. Thus, the amount of brain we have available impacts how we present symptoms of damage to a specific area.

Cognitive Reserve

Cognitive reserve, on the other hand, helps us understand why people who experience similar types of brain damage display such disparity in mental performance. Cognitive reserve is your brain's capacity to be dynamic and adaptable in the face of challenge. Think of it as your brain's ability to improvise and find alternate ways of getting a job done. If you have experienced a stroke and it affects a certain area of your brain, that area of your brain is likely associated with very specific types of mental functions. But, if your brain has been dynamically wired, your brain has developed the capacity to work around any damaged areas in a unique way. “Cognitive reserve” is developed over a lifetime of education, learning, curiosity, and pushing yourself outside of your comfort zone. It exists when there is a mismatch between brain damage and mental performance.

Cognitive reserve is like having a good navigation system (e.g., GPS) in your car. If a major highway is closed down, your GPS can still get you to your destination using city streets or an alternate route. Analogously, “cognitive reserve” allows your brain to create multiple neural pathways to produce the same action or get to the same piece of information.

Evidence on the Concept of Reserve

How do we know that brain and cognitive reserve exists? Several researchers (based from both animal models and research on human beings) have demonstrated the concept of reserve. The concept of cognitive reserve was first proposed in 1988 – when a researcher – named Robert Katzman, made a peculiar discovery. After 137 residents living in long-term care (average age 85.5 years) passed away, Katzman looked at their brains. Approximately 75 of the residents had Alzheimer’s disease (as indicated by mental assessments collected prior to death, as well as how their brains looked after they had died). Interestingly, a group of residents was also observed to have Alzheimer’s disease based on what their brains looked like, however, these 10 residents did not show mental symptoms of the disease when they were alive. Katzman concluded that the brains of these 10 individuals had built up “reserve” over their lives, resulting in larger brains and more neurons. Due to this added “brain reserve”, these 10 individuals did not show outward symptoms of Alzheimer’s disease when they were alive – even though their brains indicated that they had Alzheimer’s pathology (e.g., plaques and tangles).

In other words, people were presenting as “normal” in terms of their mental functioning, but their brains were undergoing changes associated with the development of Alzheimer’s disease. “Cognitive reserve” is the ability to retain “normal” levels of functioning amidst having a brain that is damaged.

Building Brain Reserve

When looking at the brains of people at the same stage of dementia, imaging studies have shown that those individuals with higher levels of education, more complex occupations and higher IQs had brains with more pathology (or more disease). This observation supports the notion that individuals with more reserve can tolerate more disease in the brain – but, present with similar symptoms outwardly.

But, how do we build up our own “brain reserve”?

One researcher (Gold, 1995) reported that individuals with higher levels of intellectual ability, education and socioeconomic status were more likely to develop an engaged lifestyle, which in turn contributed to their maintenance of verbal intelligence in later life. So, even if you did not have high levels of education or socio-economic status, you can take it upon yourself to create your own engaged lifestyle right now.

Living an Engaged Life

According to Denise Park from the Centre for Vital Longevity in Dallas, Texas, engagement means acquiring new information through exposure to sustained mental challenges. The difficulty is that there is no finite list of activities that fit this requirement. Information that is new and challenging for me is different from the information that is new and challenging for you. There is no one-size-fits-all solution to brain health and successful aging. Furthermore, you have to continuously engage in mental challenges for the brain benefits to emerge. In this way, the activities that you choose for yourself should be grounded in your hobbies and/or interests to ensure that you continuously engage and challenge your brain.

Living an engaged life also means moving your body daily. Research suggests that physical activity protects the physical structures of the brain – including slowing down age-related loss of brain volume.

NOTE - the amount of physical activity that you do does not need to be extreme.

One study found that engaging in leisure-time physical activity of moderate intensity (at least 2x a week) was beneficial. Another study found benefits in a group of older adults who engaged in Tai chi (mind-body exercise), for 30-minute sessions, 3x per week for 12 months. The key is to move your body - in some way - every single day, even if that means just taking a walk around your block.

If you are interested in learning more about the benefits of Tai Chi, specifically Taoist Tai Chi Arts, listen to Episode 8 of the BrainShape Podcast.

Take Home Message

“Reserve” is created when we are exposed to enriched environments (socially, physically and mentally challenging). Our environments and experiences change our brain and equip us with the brain reserve and cognitive reserve that can ultimately impact our ability to withstand brain injury – regardless of the source of that brain damage. You can create your own engaged life through leisure activities, work, and volunteering opportunities that incorporate consistent mental challenges. Also be sure to socialize on a regular basis and to engage in physical activities that are appropriate for your current capacity level. Try something new: discover Tai Chi or take in an exploratory walk around your city. Ultimately, you want to create life experiences that help you build a strong, efficient and resilient brain