Brain never stops growing, scientists find, as elderly shown to have same number of new neurons as teens

The brain never stops growing, scientists have found in landmark discovery that could help treat degenerative diseases.

Previously researchers believed that the brain did not grow any new cells after childhood, which is why it is so much harder for adults to pick up new skills or learn a foreign language.

More recent studies suggested that if specific zones of the brain were hyperstimulated then new cells could form, as was proven in London black cab drivers studying The Knowledge who were found to have an increased number of neurons in areas linked to mapping.

But a new study has found that new brain cells are actually forming all the time in their thousands, even when people are elderly.

It suggests that problems with mental ability and memory associated with old age are not down to a loss of neurons, but rather the failure of the cells to properly communicate with each other.

Dr Maura Boldrini, associate professor of neurobiology at Columbia University, in New York, said: “We found that older people have similar ability to make thousands of hippocampal new neurons from progenitor cells as younger people do.

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

“Nevertheless, older individuals had less vascularization (blood vessel formation) and maybe less ability of new neurons to make connections.”

The breakthrough could help scientists better understand the causes of dementia and how to prevent it from occurring. There are currently 850,000 people suffering dementia in Britain with the figure expected to rise to 1.2 million by 2025.

For the research, scientists looked at the hippocampus in 28 previously healthy individuals aged between 14 and 79, who had died suddenly. None were cognitively impaired or suffered depression, which can impact brain cell development.

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

They found that even in the oldest brains, new brain cells were still forming up to death.

"We found similar numbers of intermediate neural progenitors and thousands of immature neurons," the authors concluded.

However older individuals formed fewer new blood vessels within brain structures and possessed a smaller pool of progenitor cells - descendants of stem cells which turn into neurons.

Prof Boldrini surmised said brain deterioration in old age may be caused by this smaller pool of neural stem cells, the decline in blood vessels, and reduced cell-to-cell connectivity within the hippocampus.

"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," she says.

The research was published in the journal Cell Stem Cell.