- Adolescents who had used cannabis in the last year had worse episodic memory
- There were no significant differences between the 9 to 10 year old groups.
- READ MORE: Daily marijuana smokers have up to 60% higher risk of suffering from these problems
Smoking cannabis as a teenager could affect memory and learning skills, both crucial indicators of intelligence, a study suggests.
Researchers at the University of California, San Diego found that 13- to 14-year-olds who had used cannabis in the past year had worse memories than those who had never used the drug.
The study used data from the Brian Adolescent Cognitive Development study, which tracks 12,000 youth across the United States from ages 9 to 10 through late adolescence.
The researchers looked at a subset of participants who had hair samples collected when they were between 13 and 14 years old.
and participants They underwent comprehensive cognitive evaluations each year.
The researchers found that adolescents who used cannabis performed worse on tests measuring memory and experienced declines in word and sentence comprehension.
Smoking cannabis in adolescence may decrease cognitive function, study suggests
Marijuana use has increased across all age groups between 2002 and 2020, as the graph above shows.
For the study, hair samples were taken from the subjects and analyzed for three substances in cannabis; THC, THCCOOH and cannabidiol (CBD).
Tetrahydrocannabinol (THC), the main psychoactive element in the plant and is what gives a person a high. It acts on cannabinoid receptors in the brain and is believed to increase the risk of psychosis and other mental illnesses by altering parts of the brain responsible for information processing and behavior.
THCCOOH is a substance created from THC by the body, which remains in the body longer than THC.
cAnnabidiol (CBD) is a non-toxic compound found in marijuana and hemp.
Hair samples were combined with self-reported cannabis use and cognitive performance was assessed using several neurocognitive tests.
At the end of the four-year study, 601 participants had provided a hair sample and 123 of them had used marijuana.
These participants were compared with 123 adolescents who did not report cannabis use or who did not have cannabinoids detected in their hair.
Participants were matched by age, sex, race, ethnicity, and socioeconomic status to isolate cannabis use as the main difference.
The researchers found that adolescents who used cannabis showed markedly worse performance on tasks measuring episodic memory (the ability to remember specific events from the past) and small decrements in word and sentence comprehension.
Furthermore, higher concentrations of THCCOOH in hair were related to lower scores on both word and sentence comprehension and attention tasks.
Study author Natasha Wade, an assistant professor at the University of California, San Diego, told PsyPost: “When we carefully determined the group status of cannabis use in adolescents ages 13 to 14 and compared those with cannabis use to Sociodemographically matched controls, I do see that there are group differences in memory, and that greater cannabis use was associated with poor verbal skills, inhibition, working memory, and episodic memory.
‘All our analyzes were cross-sectional, so causality cannot be inferred.
“It is interesting to note, however, that when participants were initially enrolled in the study when they were between 9 and 10 years old, there were no significant differences between the groups in cognitive performance.”
Cannabis is believed to affect the neural tissue in the brain that deals with memory.
According to the National Institute on Drug Abuse, memory impairment from marijuana use occurs because THC alters the way the hippocampus, an area of the brain responsible for memory formation, processes information.
As people age, they lose neurons in the hippocampus, which reduces their ability to learn new things. Exposure to THC could accelerate this loss of hippocampal neurons.
The study was published in the journal Addictive behaviors.