New Study Shows Cannabis Boosts Memory in Older Mice

A new study found that THC in marijuana appears to have actually altered the structure of the brains' of older mice, making them more like the brains of younger mice. belterz/Getty

Can ingesting low doses of tetrahydrocannabinol (THC), the psychotropic chemical in marijuana, improve the memory of the elderly? German and Israeli researchers believe so.

In a study published in the May journal of Nature Medicine, scientists from the University of Bonn and The Hebrew University of Jerusalem found that when older mice received low doses of THC, their memories improved. The discovery may give doctors a new tool to help boost cognitive development in older people, especially those with dementia.


The findings are somewhat of a shocker, considering studies have consistently shown that long-term marijuana use by adolescents can alter the structure of their brains, specifically those areas that deal with memory. In this latest research, however, scientists say the opposite is true, at least when it comes to elderly mice.

Your Brain on Cannabinoids

THC is the most powerful of marijuana's 60 cannabinoids. All of us have natural cannabinoids in our bodies that affect how our brain cells communicate with one another. Specifically, THC interacts with a special communication network called the endocannabinoid system, which is involved in many functions including movement, pain, appetite and memory. Inside that network are special receptor cells that soak up cannabinoids.

As we get older, the ability of the endocannabinoid system to do its job declines, and the brain rapidly ages. However, THC appears to have reversed this effect in the older mice. After testing was complete, researchers looked at the brain tissue of the oldest mice. They found that the cannabis turned back the "molecular clock," actually altering the structure of the older animals' brains to make it more like the brain of the younger mice. Specifically, THC had somehow increased the number of links between nerve cells, which helps in the ability to learn.


THC for a Month

During their research, scientists studied the effects of THC on mice that were 2 months old, 12 months old and 18 months old. Scientists hooked them up to tiny pumps that released 3 milligrams of THC per day for every kilogram of bodyweight. The dosage of cannabis was delivered for a month — and slowly, so the mice did not become intoxicated. Other mice put into a control group received a placebo.

Researchers next had the mice locate an object. The oldest mice given cannabis performed just as well as youngest mice not given the drug. A final test involved recognizing familiar mice. The oldest mice on THC performed well on that test also.


Of course, mice are not people, and the results might be different when the same tests are performed on humans.