nonusers on verbal learning tests. Heavy marijuana use (generally thought to mean 4 to 6 joints per effects on day) “exerts harmful brain tissue and mental the researchers conclude.28 health,” Another review of the scientific literature determined that the evidence points overwhelmingly to “impaired encoding, storage, manipulation, and retrieval mechanisms [in the brains] of long-term or heavy cannabis users.”29 Impact on memory near- daily marijuana users, 51 long-term users, 51 short-term users, and 33 nonusers who made up the control group. The term heavy cannabis users show impairments in conclusion: “long- memory and attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis use.”30 Impact on IQ But the granddaddy of marijuana and learning studies came out in Using marijuana 2012 and astounded even the most cautious researchers. Scientists, regularly before age 18 controlling for factors like years of education, schizophrenia, and the results in an average IQ use of alcohol or other drugs, followed a cohort of over 1,000 people of six to eight fewer for more than 25 years to investigate the effect of marijuana use on points at age 38 IQ. This study finds that using marijuana regularly before age 18 compared to those who results in an average IQ of six to eight fewer points at age 38 did not use marijuana compared to those who did not use marijuana before age 18. This before age 18. astonishing finding was still true for those regular marijuana-using teens who stopped using the drug after age hypothesis is 38. “Our One of the that we see this IQ decline in adolescence because the adolescent pioneering studies brain is still developing and if you introduce cannabis, it might on marijuana use interrupt these says lead author critical developmental processes,” and memory Madeline Meier, a postdoctoral researcher at Duke University.31 helped set in motion a series of Impact on mental health subsequent studies. Nine Marijuana users have a six times higher risk of schizophrenia32 and Australian are significantly more likely to develop other psychotic illnesses. In researchers particular, females who smoke marijuana show a great vulnerability compared the to heightened risk of anxiety attacks and depression. According to a attention, study published in the British Medical Journal, daily use among memory, and verbal-reasoning skills among four groups of individuals: 102
nonusers on verbal learning tests. Heavy marijuana use (generally thought to mean 4 to 6 joints per day) “exerts harmful effects on brain tissue and mental health,” the researchers conclude.28 Another review of the scientific literature determined that the evidence points overwhelmingly to “impaired encoding, storage, manipulation, and retrieval mechanisms [in the brains] of long-term or heavy cannabis users.”29 Impact on memory Using marijuana regularly before age 18 results in an average IQ of six to eight fewer points at age 38 compared to those who did not use marijuana before age 18. One of the pioneering studies on marijuana use and memory helped set in motion a series of subsequent studies. Nine Australian researchers compared the attention, memory, and verbal-reasoning skills among four groups of individuals: 102 near- daily marijuana users, 51 long-term users, 51 short-term users, and 33 nonusers who made up the control group. The conclusion: “long- term heavy cannabis users show impairments in memory and attention that endure beyond the period of intoxication and worsen with increasing years of regular cannabis use.”30 Impact on IQ But the granddaddy of marijuana and learning studies came out in 2012 and astounded even the most cautious researchers. Scientists, controlling for factors like years of education, schizophrenia, and the use of alcohol or other drugs, followed a cohort of over 1,000 people for more than 25 years to investigate the effect of marijuana use on IQ. This study finds that using marijuana regularly before age 18 results in an average IQ of six to eight fewer points at age 38 compared to those who did not use marijuana before age 18. This astonishing finding was still true for those regular marijuana-using teens who stopped using the drug after age 38. “Our hypothesis is that we see this IQ decline in adolescence because the adolescent brain is still developing and if you introduce cannabis, it might interrupt these critical developmental processes,” says lead author Madeline Meier, a postdoctoral researcher at Duke University.31 Impact on mental health Marijuana users have a six times higher risk of schizophrenia32 and are significantly more likely to develop other psychotic illnesses. In particular, females who smoke marijuana show a great vulnerability to heightened risk of anxiety attacks and depression. According to a study published in the British Medical Journal, daily use among