Once upon a time, medical experts believed that the adult brain couldn’t make new brain cells, or more specifically, new nerve cells aka neurons. The process of manufacturing neurons, known as neurogenesis, seemed limited to the young.
Fortunately, we now know this is not the case. Although it’s true that neurogenesis surges during our early years of life and declines significantly as we age, new neurons do continue to be born.
In fact, the adult brain makes hundreds of new nerve cells every day, and they are being produced in an area of the brain that is intimately involved with memory, mood, learning, and emotion—the hippocampus. Therefore, it appears that we have a chance to help our memory as we get older—good news, indeed.
According to Jonas Frisen from the Karolinska Institutet in Sweden, the adult brain produces an estimated 700 new neurons daily in the hippocampus. Given that the human brain consists of billions of neurons, 700 new nerve cells doesn’t seem like much.
However, as Dr. Sandrine Thuret of Kings College London said during a TED talk, “By the time we turn 50, we will have all exchanged the neurons we were born with in that structure [hippocampus] with adult-born neurons.”
Since the adult brain has this ability to make new brain cells, two critical questions immediately come to mind:
- Which of our activities or behaviors can disrupt neurogenesis?
- How can we promote neurogenesis and thus help memory, learning, mood, and emotional health?
The answers to these two questions mostly involve lifestyle choices but include health issues as well. For example, Thuret explained how research has shown that depression is associated with lower production of neurons. However, treating depression with antidepressants can increase new nerve-cell production while contributing to a decline in depressive symptoms.
Similarly, cancer patients treated for their disease often report depression even after the cancer is cured, and that’s because the cancer treatment, including radiation, can have a significant negative effect on neurogenesis. Over time, however, new nerve cell production can begin again.
