A low-dose treatment with a marijuana compound can reverse the brain’s ageing processes, such as
memory loss and cognitive decline, according to a new study that paves the way for novel treatments to combat dementia.
Scientists at the University of Bonn in Germany and The Hebrew University of Jerusalem in Israel, found that old mice were able to regress to the state of two-month-old mice with a prolonged treatment with a cannabis active ingredient.
Cognitive ability decreases with increasing age. Although this process is normal, it can also promote dementia. Researchers have long been looking for ways to slow down or even reverse this process. Scientists have now achieved this in mice.
Mice have a relatively short life expectancy in nature and display pronounced cognitive deficits even at twelve months of age. The researchers administered a small quantity of THC, the active ingredient in cannabis, to mice aged two, twelve and 18 months over a period of four weeks.
Afterwards, they tested learning capacity and memory performance in the animals – including orientation skills and the recognition of other mice. Mice who were only given a placebo displayed natural age-dependent learning and memory losses.
In contrast, the cognitive functions of the animals treated with cannabis were just as good as the two-month-old control animals.
“The treatment completely reversed the loss of performance in the old animals,” said Andreas Zimmer at the University of Bonn. The researchers had earlier discovered that the brain ages much faster when mice do not possess any functional receptors for THC.
These cannabinoid 1 (CB1) receptors are proteins to which the substances dock and thus trigger a signal chain. CB1 is also the reason for the intoxicating effect of THC in cannabis products, such as hashish or marijuana, which accumulate at the receptor.
THC imitates the effect of cannabinoids produced naturally in the body, which fulfil important functions in the brain. “With increasing age, the quantity of the cannabinoid naturally formed in the brain reduces,” said Zimmer. “When the activity of the cannabinoid system declines, we find rapid ageing in the brain,” he said.
To discover precisely what effect the THC treatment has in old mice, the researchers examined the brain tissue and gene activity of the treated mice.
They found that the molecular signature no longer corresponded to that of old animals, but was instead very similar to that of young animals.
The number of links between the nerve cells in the brain also increased again, which is an important prerequisite for learning ability. “It looked as though the THC treatment turned back the molecular clock,” said Zimmer.
“It looked as though the THC treatment turned back the molecular clock,” said Zimmer.
The results are now presented in the journal Nature Medicine.