If you’re in your 20s, watching a grandparent or loved one grow older often comes with unsettling moments. In most cases, misplaced items, repeated stories or difficulty recalling names are normal slipups of aging that remind us how vulnerable memory can become over time. One of the brain regions affected during aging is the hippocampus; starting in our 60s, the hippocampus shrinks about 1-2% every year, which contributes to forgetfulness and even increases the risk of dementia. This fascinating seahorse-shaped structure in our brains is involved in memory formation and consolidation, as well as spatial navigation. Shrinkage of this integral part deep in our brains can worsen our capability to form new memories and is associated with cognitive decline as we age. For the past 20 years, neuroscientists have been devising interventions to slow the shrinkage of the hippocampus that occurs when we age. That might seem like something out of a science fiction movie; however, it leads them to a very odd but interesting question–what if we could grow our hippocampus ourselves? No external intervention, no medication, and no scary surgeries would be involved.
Neuroscientists have the answer
Turns out we actually can. Among others, a study published in Erickson (2011) provided a hopeful answer: aerobic exercise. It is a kind of physical exercise where the body burns glucose and fat for a sustained period of time to make energy. Unlike short bursts of strength training or sprinting, aerobic exercise keeps your heart rate steadily elevated. The study proved that an exercise as simple as brisk walking regularly, can actually grow the hippocampus and improve memory in older adults. Previously, animal studies in the 1990s and early 2000s (notably by Henriette van Praag and colleagues) had proved that voluntary running boosted neuronal birth in the hippocampus of rodents. Moreover, many observational studies have linked physical activity and better cognition and memory in older adults. In Erikson (2011), researchers studied 120 adults ages 65 or older over the course of a year. To control for factors that could distort the research findings, they screened for participants who did not have dementia, a condition where patients suffer from severe brain shrinkage. Selected participants were randomly assigned to either an aerobic exercise group or a control group. The aerobic exercise group walked briskly three times a week while the control group did stretching and mild muscle toning activities. The researchers measured their fitness levels, collected blood samples, scanned their brains with MRI to track changes in hippocampal size, and also tested their memory.
WHAT DOES THE RESEARCH TELL US?
The results were striking. MRI scans showed that the aerobic exercise group not only stopped hippocampal shrinkage but actually grew their hippocampal volume by about 2%. This effectively reversed one to two years of natural aging in the brain Moreover, the brain growth was linked to higher levels of a protein called BDNF (brain derived neurotrophic factor). This protein supports neurogenesis or the birth of new neurons and hence; stronger brain connections. Spatial memory was also tested and, amazingly, there were significant improvements in remembering routes or locations. On the contrary, the control group continued to experience the expected decline. In short, the study demonstrated that the aging brain is more adaptable and resilient than we once believed, and that step by step, something as simple as a brisk walk can reverse age-related brain shrinkage.Â
This resilience and adaptability of our beautiful brains is explained by the remarkable capacity of neuroplasticity. It’s the property of the brain that allows it to change, adapt and recognize neural connections throughout life by forming new neurons, making new connections and essentially rewiring to adapt to any new learning, stimuli, or even damage due to injury. In this study, the fact that the brain is growing its hippocampus and connections required for spatial learning contextualizes the concept of neuroplasticity.
What can we do about it?
If you do have aging loved ones, you have learned something powerful today: it’s never too late to protect the aging brain. Encouraging your older loved ones to develop a consistent aerobic exercise routine, even as simple as walking a few times a week, can make a significant difference in memory and spatial learning. There are numerous other established health benefits to exercise, including cardiovascular disease risk reduction, better mental health, and overall wellbeing. Another lesson from this research worth noting is that building good habits like staying active and hitting your “steps” goal for the day can truly benefit your personal long-term health. Isn’t it amazing how the secret to being a sharp and quick witted 60 year old a few decades from now lies in something as simple as a brisk walk? While we can’t completely reverse brain aging, regular aerobic activity offers a natural, low-cost way to strengthen neuronal connections and prevent natural shrinkage of certain parts like the hippocampus. So the next time you invite your grandparents for a walk, remember that those steps are more than a low intensity workout, they’re an investment in keeping memories alive, and in protecting the very structure of their brains.Â
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