A new study found that teens who use marijuana daily might suffer from poor memory when they reach adulthood.
Researchers at the Northwestern University Feinberg School of Medicine looked at the brain scans of 97 participants to determine how marijuana affects the brain of the users. The study involved healthy individuals, people who have marijuana use disorder, people diagnosed with schizophrenia but do not use marijuana, and marijuana users who also have schizophrenia. The marijuana users started using it daily when they were between 16 and 17 years old for three consecutive years.
The participants listened to a series of stories for a minute and were then asked to recall details about 30 minutes later.
The memory test showed that the schizophrenic marijuana users scored 26 percent lower than those who have the mental disorder but do not use marijuana. It also revealed that teens who abused marijuana performed 18 percent worse on the assessment than the non-users.
The analysis of the brain scans revealed that the marijuana users’ hippocampus showed more abnormalities compared to the non-users. Hippocampus is the region of the brain responsible for storing both short-term and long-term memories.
The changes were observed two years after quitting marijuana use. The longer they used marijuana, the more abnormal their hippocampus showed. The study is the first to link heavy marijuana use with abnormalities in the hippocampus.
“Both our recent studies link the chronic use of marijuana during adolescence to these differences in the shape of brain regions that are critical to memory and that appear to last for at least a few years after people stop using it,” lead study author Matthew Smith, assistant professor in Psychiatry and Behavioral Sciences, said in a university news release.
The researchers admitted that further study is needed to determine if marijuana is indeed responsible for the poor memory.
“It is possible that the abnormal brain structures reveal a pre-existing vulnerability to marijuana abuse,” Smith said. “But evidence that the longer the participants were abusing marijuana, the greater the differences in hippocampus shape suggests marijuana may be the cause.”
The study was published in the March 12 issue of Hippocampus.
