The secret to living longer may be all in your head after all.
A team of neuroscientists has found a way to extend the lives of lab mice by simply switching a brain pathway on and off, according to a paper published May 1 in the journal Nature.
"If we just activated this pathway in the hypothalamus, it accelerated aging," study researcher Dongsheng Cai, of the Albert Einstein College of Medicine, told Business Insider. "If we inhibit this pathway, we can slow down aging. There were lots of assessments that showed inhibiting it led to an increase of lifespan by roughly 20%. So, that's pretty remarkable."
Aging and the brain
The scientists focused on the hypothalamus because it is the region in the brain responsible for growth and metabolism — two things that change as we age. Cai and colleagues have published previous papers on the role of the hypothalamus in age-related metabolic diseases like diabetes, hypertension, and obesity.
But Cai felt that the information on what actually causes aging was lacking. Aging has systemic effects on the body: hitting many different organs and causing many different diseases at once.
He thought that chemicals in the brain associated with age-related diseases, like metabolic syndromes and cancer, might also play a role in aging.
"Aging by itself is not a disease," Cai said, "but it is a risk factor for many diseases. It is more like a ground for the development of many epidemic diseases like diabetes and neurodegenerative disorders."
Stress and inflammation
In mice, the researchers experimented with a protein complex involved in inflammation in the hypothalamus called NF-kB. Inflammation is an overreaction of our body's immune system in response to stress. Inflammation can help heal and fight disease, but too much inflammation can be dangerous.
They were surprised by how much of an impact turning off NF-kB in the hypothalamus had on how long the mice lived — about 20% longer. On the flip side, turning it to overdrive accelerated aging.
The researchers also discovered for the first time that a brain peptide involved in reproduction, called GnRH, plays an important role in neurogenesis — the growth of new brain cells. When NF-kB is turned up, GnRH is turned down, leading to fewer new brain cells and quicker aging.
Turning down NF-kB and turning up GnRH could work together to decrease inflammation in the brain and stimulate the growth of new brain cells, fighting the signs of aging and diseases that come with it, the researchers said in a press release.
A longer life
Harvard researcher David Sinclair told Nature News that this finding is "a major breakthrough in ageing research."
Scientists used to believe that we are more-or-less born with a finite number of brain cells that we gradually lose over time through aging or behaviors (like a few too many shots of whiskey).
But over the last decade or so, researchers have found that new cells grow in numerous regions of the brain, throughout adulthood.
A complex web
Researchers thought that an important factor in age-related brain cell loss might be chronic inflammation of cells. Both environmental factors and intrinsic changes in cells can contribute to inflammation in the brain, so the picture is more complex than just this pathway.
"This is only one pathway," Cai said. "Although we believe it is important one, I also think there could be other molecules involved altogether. So we can speculate that if we manipulate more than just this pathway, there could be an even greater effect."
This finding may one day give us the power to extend our lives.
"In the meantime, we also hope develop methods targeting this pathway for potentially practical treatment for human beings," Cai said. "We need to do many more assessments in mice, but eventually is could lead up to human studies."
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