Elderly adults grow just as many new brain cells as 20-year-olds

Elderly people grow just as many new brain cells as youngsters, according to a new study.

Researchers at Columbia University have shown for the first time that healthy men and women as old as 79 can generate just as many new brain cells as someone aged 14 can.

There has been controversy over whether adult humans grow new neurons, and some research has previously suggested that the adult brain was ‘hard-wired’ and that adults did not grow new neurons.

But the new study, published in the journal Cell Stem Cell, counters that notion, shedding new light on possible pathways to treatments for psychological and neurological conditions like Alzheimer’s disease. 

The Columbia researchers were the first to look at the entire hippocampi of brains for signs of their abilities to form new neurons (pictured). Elderly brains were forming just as many as younger ones, they found 

Lead author Dr Maura Boldrini, associate professor of neurobiology at Columbia University says the findings may suggest that many senior citizens remain more cognitively and emotionally intact than commonly believed. 

Neurons are the building blocks of the brain’s circuitry. The stronger and more complex that circuitry is, more able to form new memories we are. 

The hippocampus also controls our emotions, so the ability to continuously form new circuits in that region of the brain is also key to psychological changes. 

This circuit-building process may break down for those suffering psychological disorders, but for most people, with age will come a fading ability to form episodic memories, which are our bank of first-person experiences. 

Scientists have previously thought that memory may begin to fail because no new neurons were growing in this part of the brain, but Dr Boldrini’s research suggests otherwise.  

OTHER RESEARCH SAID BRAIN CELLS STOP GROWING AT 13 – HOW CAN THAT BE? 

Last month, Nature published a study by the University of California, San Francisco claiming that no new brain cells form in the hippocampus after age 13. 

But it used smaller, inconsistent brain tissue samples, while the Columbia study used an unprecedented, thorough new method.  

The UCSF researchers looked at the same marker of immature neurons as the Columbia researchers did in brain tissue infants, children, adolescents and adults. 

The oldest brain that they found the immature brain cells in had belonged to a 13-year-old. 

But, Dr Boldrini of Columbia University says that the UCSF methodology left room for error.   

Brains to study are hard to come by, and most scientists collect them from various sources, preserving them in a variety of times, and sometimes as much as two days after the donor has died, and without full medical histories or toxicologies.

The UCSF researchers took brain tissue from living donors as well as some that had been dead for two days, and collected them from several different countries. 

They then examined just four or five cross-sections of the hippocampi, not the whole thing.  

But Dr Boldrini says that Columbia’s collection of brains is unique, as was her methodology. 

She and her team made sure that they froze the donor brains immediately, did extensive medical history and toxicology research on them, and used a comprehensive sampling method to make sure they examined every part of the hippocampus. 

This ensured that all of the donors had good cognitive function before death, and none of them had had drugs that could change their brains still in their systems.  

‘Nobody has done this before,’ said Dr Boldrini.  

‘We found that older people have similar ability to make thousands of hippocampal new neurons from progenitor cells as younger people do,’ Dr Boldrini said. 

She and her team looked at proteins that are harbingers of new neuron growth, and found that older people had just as many on the verge of maturation as younger ones did. 

‘We also found equivalent volumes of the hippocampus – a brain structure used for emotion and cognition – across ages.

‘Nevertheless, older individuals had less vascularization and maybe less ability of new neurons to make connections,’ Dr Boldrini explained.  

The researchers conducted autopsies on hippocampi from 28 previously healthy people aged 14 to 79 who had died suddenly.

The study is the first time researchers looked at newly formed neurons and the state of blood vessels within the entire human hippocampus soon after death.

The researchers had determined that study subjects were not cognitively impaired and had not suffered from depression or taken antidepressants, which Dr Boldrini and colleagues had previously found could impact the production of new brain cells. 

This, she says, is an important distinction from previous studies, including one published last month that claimed neuron production all but halts after age 13.  

Waning production of neurons and an overall shrinking of the dentate gyrus, part of the hippocampus thought to help form new episodic memories, was believed to occur in aging humans as well.

But ‘we all know people that are in their nineties and are sharp,’ said Dr Boldrini, and her findings reveal, in part, why that is possible.   

The researchers from Columbia University and New York State Psychiatric Institute found that even the oldest brains they studied produced new brain cells.

Dr Boldrini added: ‘We found similar numbers of intermediate neural progenitors and thousands of immature neurons.’

Nevertheless, older people form fewer new blood vessels within brain structures and possess a smaller pool of progenitor cells – descendants of stem cells that are more constrained in their capacity to differentiate and self-renew.

As people age, their neural plasticity, or the ability of their brain to change, declines (blue to brown) but the hippocampus continues to make the same number of new neurons (green to black), a graphic from the new study shows 

This can also impair the ability of these neurons to make connections. So the raw materials (the neurons) may still be plentiful, but older brains may not be able to link them up to bring them into its circuitry, Dr Boldrini theorized.  

Dr Boldrini surmised that reduced cognitive-emotional resilience in old age may be caused by this smaller pool of neural stem cells, the decline in vascularisation, and reduced cell-to-cell connectivity within the hippocampus.

She added: ‘It is possible that ongoing hippocampal neurogenesis sustains human-specific cognitive function throughout life and that declines may be linked to compromised cognitive-emotional resilience.’

Dr Boldrini says that future research on the aging brain will continue to explore how neural cell proliferation, maturation, and survival are regulated by hormones, transcription factors, and other inter-cellular pathways. 

‘What we would like to do next is to understand the molecules that regulate the survival and maturation of these cells, and could possibly compare them to the brains of people with Alzheimer’s and vascular dementia,’ said Dr Boldrini. 

By comparing the perfectly healthy brains she and her colleagues looked at in this study to diseased ones, Dr Boldrini hopes that they could find out whether connectivity is the difference between the two and ‘find a mechanism for treating diseases like Alzheimer’s that doesn’t really have any decent treatment’ she said. 



Read more at DailyMail.co.uk