Brain Cells

Do they continue to grow at elderly age?

By Navid Amarlou
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Given the increasing life expectancy, the elderly population is growing. This makes understanding how the brain reacts to aging all the more important. A particular interest of scientists is in neurogenesis in the hippocampus, or the production of new neurons in the hippocampus of the brain. This is a part of the brain that is vital in turning short term memory into long term memory, along with other tasks such as navigation.

For years now, we have had an understanding that neurogenesis halts with age and subsequently the matter has been debated upon heavily. In rodents and primates similar to humans, the ability to produce new neurons slows with age and so it was a widely believed idea accepted by the scientific community that the human brain must surely do the same. Given that a part of the brain called the Dentate Gyrate, which plays an important role in the formation of new memories, shrinks in size.

This idea has recently been revisited by researchers in Columbia University and New York State Psychiatric University, which conducted an experiment in hopes that they may finally reach a conclusion.

Previous studies explored hippocampal volume in aging humans, but the results were greatly affected given the technological limits at the time as to accurately scanning the brain.

In order to circumvent these issues, the researchers inspected the whole, autopsied hippocampi of 28 men and women, ages ranging from 14–79, who had died suddenly. None of these individuals had long-term health problems or cognitive deficits, or had a significantly stressful life event in their last 3 months of life. They also made sure that the subjects had not been depressed or taking antidepressants given a prior study they did that showed that antidepressants had negative effects on neurogenesis.

The study was the conducted the first to asses the number of newly formed neurons and blood vessels in the human hippocampus following the subjects death. The conclusions of this study were that older men and women can generate the same number of brain cells as younger people.

”We found that older people have similar ability to make thousands of hippocampal new neurons from progenitor cells as younger people do,” according to Dr. Maura Boldrini, a associate professor of Neurobiology at Columbia University. “We also found equivalent volumes of the hippocampus (a brain structure used for emotion and cognition) across ages.”

Where they did find that neurogenesis does not halt, there are issues that become more prominent with age. A primary issue expressed in the study was decreased vascularization in the brain and decreased progenitor cells. To make this more clear, the cells in the hippocampus do continue to be produced though they are less connected and have a reduced supply of nutrients and oxygen.

Dr. Boldrini wants to continue research on neurogenesis  and how it is affected by thing such as transcription factors, hormones, and other biochemical pathways. This research can potentially open many doors in helping us understand the brain and how it changes as we age.

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