Sometimes medical studies provide surprising information. Sometimes they do not. An example of that was a study that was published in the Journal of the American Medical Association open network on January 28, 2025.
The study looked at 1003 young adults. They divided them into three groups. The groups were heavy cannabis users, moderate cannabis users and nonusers.
They looked at the individuals with what is called functional MRI (fMRI). What this test does is look at areas of the brain that light up when people are using those areas of their brain. We can compare normal function in those areas to abnormal function in those areas.
They looked at 7 different tasks for the study subjects. The tasks included things like emotion and language. They also included working memory.
The working memory task involved a series of pictures. One of the tests was that they showed in the individual an image. Then they asked that individual to select the same image from a group that was subsequently presented. Another test asked the individual to identify an image that had been seen two images ago.
They checked the fMRI during these tasks. What they found was that heavy users had lower activation of their brains when asked to do working memory tasks. They also found that the results were worse when the use was more recent. There were three areas of the brain that were most affected.
They also did a test called theory of mind. This refers to the understanding that others’ beliefs, desires, intentions, emotions and thoughts may be different from one’s own.
This is one of the symptoms of autism. That is why autistic children will focus on a subject like dinosaurs or trains. Then when someone changes the subject, they go right back to it. They do not realize that others may not want to hear about the same subject as they do.
The testing suggested a problem in this area but there was not enough data to be sure. The conclusions were that this kind of study needs to be done in larger numbers of patients to see if the effects that were noted hold up when that happens. For that reason the study was not conclusive. However, it also was not a real surprise.