Dementia: cannabis rejuvenates mouse brains

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

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Memory decreases noticeably with age. This process cannot yet be reversed. Now, low-dose cannabis did just that in mice: they were mentally just as fit again as much younger conspecifics.

Cannabis actually has a reputation for obscuring rather than promoting intellectual performance. In fact, at least teenage brains seem to be sensitive to the drug - it could disrupt their brain development, researchers speculate.

Experiments with mice have shown that the cannabis active ingredient THC could have a positive effect on the performance of older brains. A dose so low is sufficient that there is no intoxicating effect.

Missing docking points in the brain

A research team from Bonn and Jerusalem had previously found that the brain of mice ages much faster if they lack certain receptors. Certain endogenous cannabinoids attach to these so-called cannabinoid 1 (CB1) receptors in order to trigger special reactions.

But THC can also accumulate - this is what the intoxicating effect of the drug is based on. With increasing age, the amount of cannabinoids naturally formed in the brain decreases, ”says Prof. Zimmer. "When the activity of the cannabinoid system decreases, we find that the brain is aging rapidly."

Fast aging mice

Mice naturally have a relatively short lifespan. At the age of twelve months, their intellectual capacity declines noticeably. The researchers administered a small amount of THC to the rodents at the age of two, twelve, or 18 months over a period of four weeks.

Then they tested the learning ability and memory performance of the animals - including, for example, the orientation ability and the recognition of conspecifics. Mice that were only given an active substance-free placebo showed the typical age-dependent learning and memory losses.

Fit like young animals

The mental abilities of the cannabis-treated animals, on the other hand, were just as good as those of the two-month-old control animals - even if their mental abilities had already deteriorated beforehand. "The treatment completely reversed the loss of performance in the old animals," reported Prof. Andreas Zimmer from the Institute for Molecular Psychiatry at the University of Bonn.

More nerve connections in the brain

In order to be able to understand the effects of THC in the brains of older mice, the researchers examined brain samples from the treated mice. In fact, the activity of the genes no longer corresponded to that of old animals, but was rather very similar to that of young animals.

The number of connections between nerve cells in the brain also increased again. This is an important prerequisite for the ability to learn. "It looked like the THC treatment reset the molecular clock," says Zimmer.

Does it also work for people?

In the next step, the researchers want to investigate whether THC can reverse the aging processes of the brain in humans and increase cognitive performance again. Because the fact that the effect occurs in mice does not mean that it also works in humans. Nevertheless, the researchers hope that perhaps even dementia patients could benefit from this.

Cannabis products are already approved as drugs. Among other things, they help some pain patients or relieve loss of appetite and nausea in cancer patients.

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