Some people have the brain changes associated with Alzheimer's disease but never develop dementia. While others experience worsening memory and thinking problems, these individuals remain mentally sharp despite signs of the disease in their brains. Scientists have long struggled to explain why.
Now, researchers at the Netherlands Institute for Neuroscience have uncovered a promising clue. Their findings suggest that a rare group of brain cells, known as immature neurons, may behave differently in people who resist Alzheimer's symptoms. Rather than simply replacing damaged cells, these neurons could help protect the brain from the harmful effects of the disease.
This remarkable ability is known as cognitive resilience. It describes how some people maintain their memory and thinking abilities even when their brains show signs of damage or disease. "Around 30 percent of older adults who develop Alzheimer's disease never experience its symptoms," says Evgenia Salta, senior author of the research.
"We really don't know why. That's a big mystery, and a very important one." Understanding this mystery could transform how scientists approach Alzheimer's, shifting attention from what causes brain cells to deteriorate toward what allows certain brains to remain healthy and functional. One possible explanation for cognitive resilience is that some brains have a greater ability to repair or protect themselves as Alzheimer's progresses.
"Perhaps they can add new brain cells to a network that is degenerating," Salta says. This possibility involves a biological process called adult neurogenesis, which refers to the production of new nerve cells (neurons) in an adult brain. Neurons are specialized cells that transmit information throughout the nervous system, allowing us to think, learn, remember, and respond to our surroundings.
Scientists have established that adult neurogenesis occurs in several animal species. Whether it continues to happen in the adult human brain, however, has been a subject of scientific debate for decades. If the human brain can produce new neurons later in life, those cells might help maintain important connections as aging and disease damage existing networks.
Extract — continue reading at the source.
