Researchers at Columbia University find evidence that healthy older adults can generate as many new brain cells as younger people.
For well over a decade, research has shown that the brain is able to form new connections; a process referred to as neuroplasticity. Since then, there has been an ongoing debate over whether the aging adult human brain can also produce new cells (neurons). Now, a study published in the journal Cell Stem Cell shows that aging brains are capable of generating new cells, suggesting that many older adults can remain more cognitively and emotionally intact than recently believed.
A team of researchers at Columbia University and the New York State Psychiatric Institute examined hippocampi from 28 healthy individuals aged 14-79 who had died suddenly. Those individuals had to be free of prior cognitive impairment, and not have a history of depression or antidepressant use, all of which could hinder the production of new brain cells. Examining these brains, scientists were able to look for any newly formed neurons, and to see whether there were differences in the blood vessels of younger and older individuals.
The hippocampus is a brain structure that is essential for learning and memory. Prior studies with primates and rodents show that new hippocampal cell growth decreases with age, which can lead to a shrinking of the dentate gyrus, an important part of the hippocampus associated with forming new episodic memories. Based on these studies, it is believed that aging humans suffer a similar fate, which might explain some forms of cognitive decline.
To assess cell growth, researchers characterized and quantified the number of cells, including neural stem cells at various stages of maturity, tissue volume, and angiogenesis (the formation of new blood vessels) in each region of the hippocampus. For cell counts, they relied on stereology, a gold standard strategy for counting cells that allows for unbiased 3D estimates of cell numbers.
Using this approach, they discovered no evidence of a decline in the number of young brain cells with age. Specifically, similar numbers of “intermediate neural progenitors” and literally thousands of immature neurons were found among both the younger and older brains. This suggests that the brain is able to produce new hippocampal cells even at an advanced age.
There was one important difference detected between the brains of younger and older individuals. Older adults had fewer new blood vessels within the brain, and possessed fewer groups of cells that can flexibly differentiate and regenerate. This may mean that older brains are less cognitively and emotionally resilient, which may potentially explain some declines in cognitive function that many experience with age. Indeed, prior research shows that the hippocampus is particularly vulnerable to the effects of prolonged life stress.
Results of this investigation contrast those of a similar study that found that cell production becomes almost nonexistent over time, suggesting that more research will be needed before any definitive conclusions can be made.
Yoga and other healthy activities may promote brain cell growth
Although this study did not examine the relationship of lifestyle factors to an individual’s potential for hippocampal brain cell regeneration, it is possible that engaging in healthy activities may have played a role in cell growth, particularly for older adults.
Studies have shown that practices such as yoga and meditation are linked to an increased volume of the hippocampus in middle-aged and elderly adults. Functionally, there is also evidence that regular yoga practice may improve executive function in older adults.
In one study published in Biological Psychology, a sample of 118, sedentary older adults (mean age = 62 years) were assigned to attend either an 8-week Hatha yoga intervention (n=61), or a stretching control group (n=57) 3 times per week for 8 weeks. At the end of 8 weeks, yoga participants showed significantly improved working memory, cognitive flexibility and efficiency, and executive function compared to the control group.
Yoga and other forms of moving meditation integrate physical movement with breath awareness and focused attention. This can facilitate neural communication between the brain and body, and the integration of both top-down and bottom-up cognitive processing. This ability to integrate mind and body in the service of sustained focus, attention, self-awareness and self-regulation may explain why yoga and meditation may enhance cognitive capacities and impact related brain networks.
These studies paint an optimistic picture of the brain’s incredible potential to change itself throughout the lifespan. Additional research is needed to understand why and how this occurs, and whether or not mindfulness-based practices may be directly linked to the ability of aging brains to generate new neurons.
Maura Boldrini, Camille A. Fulmore, Alexandria N. Tartt, Laika R. Simeon, Ina Pavlova, Verica Poposka, Gorazd B. Rosoklija, Aleksandar Stankov, Victoria Arango, Andrew J. Dwork, René Hen, J. John Mann. Human Hippocampal Neurogenesis Persists throughout Aging. Cell Stem Cell, 2018; 22 (4): 589 DOI: 10.1016/j.stem.2018.03.015