Researchers Turned Back Time in the Brains of Aging Mice

vintage-clock_mediumIt’s a fact: our memory power slows down with age. But does it have to? Researchers   at the University of Bonn in collaboration with The Hebrew University of Jerusalem recently showed that when it comes to memory power, it might be possible to turn back time. In their study, these scientists were able to restore the memory powers of youth to aging mice through a prolonged low-dose treatment with a cannabis active ingredient. This may open up exciting new options for improving cognition in general and perhaps even for treating dementia, which currently has no cure. The results of the recent study were published in the journal Nature Medicine.

Why We Start Forgetting

Our brain is an organ, just like our hearts, livers, kidneys, etc. All organs age, which leads to decreased function. With regard to the brain, decreased function can mean more difficulty learning new things or increased struggle paying attention to several things at once. These changes are called “mild cognitive decline” and are considered a normal part of aging, but unfortunately mild cognitive decline is also linked to dementia. For that reason, researchers are very interested in identifying ways to slow down, prevent, or even reverse mild cognitive decline.

The Experiment that Turned Back Time

For the collaborative study conducted by scientists at the University of Bonn and The Hebrew University of Jerusalem (Israel), the researchers administered a small quantity of THC, the active ingredient in the hemp plant (cannabis), to mice. Because it was such a low dose, it had no intoxicating effect in the mice.  The THC was given for 4 weeks to 2 groups of mice, divided by age:

  • 12 months
  • 18 months

A placebo was given to a control group of mice of the same ages, 12 and 18 months. Because mice have a relatively short life expectancy, they tend to display significant cognitive deficits as early as 12 months of age. Young mice, aged 2 months, were used as a baseline for the memory and cognition of healthy young mice.

After the 4-week study period, the scientists tested all the mice for learning capacity and memory performance. Old mice given the placebo all showed the expected cognitive deficits and memory loss. Mice given the cannabis, on the other hand, tested just as well as the youthful, 2-month control mice!

“The treatment completely reversed the loss of performance in the old animals,” said Professor Andreas Zimmer from the Institute of Molecular Psychiatry at the University of Bonn.

Many Years of Research

This exciting new study follows many years of careful research. First, scientists discovered that some mice lack functional receptors for THC, and that the brains of such mice age much faster than other mice. The receptors in question are called cannabinoid 1 (CB1) receptors. CBI receptors are associated with the intoxicating effect of THC, which accumulates at the receptor. However, our bodies also produced cannabinoids naturally, and those natural
cannabinoids fulfill essential functions in the brain. Unfortunately, our natural cannabinoids drastically decline old-school-photo_facebookwith age. “When the activity of the cannabinoid system declines, we find rapid aging in the brain,” Zimmer says.

After confirming the ability of THC to return the brain function of older mice to that of young mice, the researchers wanted to know exactly what was happening in the brain tissue and gene activity of the treated mice. They were surprised to discover that the molecular signature of these mice no longer corresponded to that of old animals, but rather looked very much like that of young animals. Additionally, the links between the nerve cells in the brain also increased dramatically, an important factor for learning ability. “It looked as though the THC treatment turned back the molecular clock,” Zimmer says.

But Could it Work in Humans?

In many instances, cannabis products are already permitted for legal medical use—for example, as pain relief. Therefore, precedence exists for cannabis as a medical treatment. What is now needed is a clinical trial to test whether and to what degree THC can reverse aging in human brains and lead to improved memory and cognition.

So far, scientists have shown enthusiasm for these early results. The North Rhine-Westphalia science minister Svenja Schulze said about the study: “Although there is a long path from mice to humans, I feel extremely positive about the prospect that THC could be used to treat dementia.”

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