New research suggests that humans produce new neurons throughout their lives, refuting the some previous studies that have suggested this process ends in the late teen years. The issue has been a focus for debate among scientists, and the new findings could ultimately pave the way for new treatments for dementia and other neurological disorders, according to the Guardian.
While scientists already know that new neurons are produced in young children, it’s been unclear how far this production extends into adulthood, and whether the rate of production falls as part of the aging process, as researchers have previously observed in mice and primates. In recent years, studies had provided mixed results on the issue. But the new study, published in the journal Cell Stem Cell, sheds new light on the question.
According to the study’s first author, Dr. Maura Boldrini of Columbia University:
“The exciting part is that the neurons are there throughout a lifetime. It seems that indeed humans are different from mice – where [production] goes down with age really fast – and this could mean that we need these neurons for our complex learning abilities and cognitive behavioral responses to emotions.”
The study focused on data from deceased individuals, who unlike in other studies on the topic, were healthy up until death. The 28 individuals ranged from the age of 14 to 79, and had their hippocampus collected immediately after death. The researched look at the formation of new blood vessels, the volume, and the number of cells at different points of growth, in the part of the hippocampus where new neurons are produced, called the dentate gyrus.
Boldrini explained that prior studies have shown that humans could be born with a finite amount of “mother cells,” stem cells that can become a variety of different cell types. And the new study did find that as people aged, the number of these “mother cells” decreased in the middle and front regions of the dentate gyrus. But the “daughter cells” that these cells produce did not decrease with age.
“Those daughter cells are the ones that exponentially divide and make many more cells and differentiate towards becoming a neuron…We can still make enough neurons even with fewer left of these ‘mothers’,” according to Boldrini.
However, the team did find a decrease in the amount of cells that produce substances connected to the brain’s potential for change and adaptation, called neuroplasticity. The study notes that this may be why people may become more emotionally vulnerable with age.
According to Boldrini, the next step will be to look at this activity in the brains of Alzheimer’s patients and people with emotional problems, as a step towards finding out how to properly treat such conditions.