In a paper recently published in the journal Nature Medicine, a group of researchers from Spain detail their study of the brains of deceased people, indicating that our “neck-tops” are perfectly capable of growing brand new cells well into advanced age.
This finding comes as somewhat of a surprise in light of the recent debate among scientists regarding the brain’s capacity for neurogenesis in the years following childhood, as well as the specific parts of the brain where this could be happening, and the survival rates of the new cells (if they form at all, that is).
For the study, the research team relied on a state-of-the-art preservation method, whereby the brains of deceased people are suspended in a liquid solution known to keep neuronal tissue fresh, and examined them within mere 10 hours of death.
Samples were taken from the hippocampi of people with or without Alzheimer’s disease (AD) for comparison. The hippocampus was chosen due to the reason that previous studies have pinpointed it as the most likely site of adult neurogenesis.
A new, more reliable technique of preserving human brains after death indicates that new neurons are generated even in aging brains, including those beset by Alzheimer's disease (albeit to a much lesser extent). Image: Mohamed Hassan via pxhere.com, CC0 Public Domain
To sort out old neurons from new ones, the researchers looked for doublecortin, which is a protein found in neurons during early stages of development. Doublecortin can be detected by looking at tissue through a microscope.
The research team announced that it has found “thousands of immature neurons” within the brain of “neurologically healthy human subjects up to the ninth decade of life”. In sharp contrast, “the number and maturation of these neurons progressively declined as AD advanced”.
“These results demonstrate the persistence of AHN [adult hippocampal neurogenesis] during both physiological and pathological aging in humans and provide evidence for impaired neurogenesis as a potentially relevant mechanism underlying memory deficits in AD that might be amenable to novel therapeutic strategies,” wrote the authors in their paper.
While this may not be final proof that adult brains are capable of neurogenesis, the findings are quite striking, especially considering the advanced preservation technique, which could potentially explain their discrepancy with regards to past studies.
Sources: abstract, medicalxpress.com