Marijuana’s main mind-altering compound, Tetrahydrocannabinol (THC), may improve memory in older people, according to a recent German study.
Research in mice showed that the older animals experienced “a dramatic improvement in cognitive functions” after they were given small daily doses of the psychoactive compound for about a month, said study co-author Andreas Zimmer, a professor of molecular psychiatry at the University of Bonn.
Previous research in young animals, as well as in teenage and young adult humans, has suggested that THC may impair cognition, but it was not clear how the compound might affect older individuals.
In the new study, which was published in the journal Nature Medicine, the scientists looked at 17 young mice, that were two months old; 24 mature mice, that were one year old; and 29 mice that were 18 months old, which is considered old for mice. The researchers implanted tiny pumps into all mice in the study.
In about half of the mice in each age group, the pumps contained a small amount of THC that was released into the mice daily for about a month. In the other half of the animals, the pumps contained a control substance, without THC.
The team went on to conduct a few behavioral experiments to test the mice’s cognitive skills, including their memory and ability to learn new information.
In one of the tasks, the researchers put the mice in a pool of water with a hidden platform that allowed them to escape the water once they located it. In the control group, the mature mice and the old mice took longer to learn to climb out than the young mice.
The mature mice and old mice that had been treated with THC learned the task faster than the control mice in corresponding age groups, however.
At times, THC seemed to improve the older mice’s memory to such an extent that some aspects of their memory were as good as those of young mice.
In contrast, THC seemed to worsen the performance of cognitive tasks in younger mice. This finding is consistent with previous research that has shown the detrimental effects that THC may have on cognition in young people and animals, according to the study.
To determine the potential mechanisms behind the findings, the scientists also examined how THC interacted with gene expression in a brain region called the hippocampus in the mice.
They found that administering the compound to the older mice led to a change in those patterns, bringing them back to a state similar to the patterns seen in the young control mice.
In contrast, administering THC to the young mice led to a gene expression pattern that resembled that of the older control mice.