Marijuana use has become increasingly socially acceptable with some states legalizing the use of the drug. Several studies presented at the American Psychological Association’s 122nd Annual Convention demonstrate that regular use of cannabis, define as once a week, is not safe and may result in neurocognitive damage.
A 2012 study revealed that 6.5 % of high school seniors report smoking marijuana daily. Thirty one percent of young adults (18-25) used marijuana in the last month. A 2012 longitudinal study following 1,037 people from birth until 38 years of age found Addiction can cause loss of six IQ points by adulthood.
“It needs to be emphasized that regular cannabis use, which we consider once a week, is not safe and may result in addiction and neurocognitive damage, especially in youth,” said Krista Lisdahl, PhD, director of the brain imaging and neuropsychology lab at University of Wisconsin-Milwaukee.
Lisdahl also presented research on the impact of regular marijuana use and corresponding changes in brain structure, particularly relevant among adolescents. Abnormalities in the brain’s gray matter, which is associated with intelligence, have been found in 16- to 19-year-olds who increased their marijuana use in the past year, she said. These findings remained even after researchers controlled for major medical conditions, prenatal drug exposure, developmental delays and learning disabilities, she added.
“When considering legalization, policymakers need to address ways to prevent easy access to marijuana and provide additional treatment funding for adolescent and young adult users,” she said. She also recommended that legislators consider regulating levels of tetrahydrocannabinol, or THC, the major psychoactive chemical in marijuana, in order to reduce potential neurocognitive effects. THC produces most of the psychological effects associated with the drug and is also linked to an increased risk of depression, anxiety and psychosis.
The levels of THC have increased in different legalized strains of Marijuana, a factor that was not considered in prior research on the drug.
“Recent studies suggest that this relationship between marijuana and mental illness may be moderated by how often marijuana is used and potency of the substance,” said Alan Budney, PhD, of Dartmouth College.