Dr. Madeline Meier Responds to Latest IQ and Marijuana Studies

By January 19, 2016Uncategorized

Today, Dr. Madeline Meier, Professor at Arizona State University, commented on two studies (here and here ) regarding IQ and marijuana use. Dr. Meier stands firm by her previous research showing an up to 8-point reduction in IQ among heavy marijuana users. Her statement is here:

“Unfortunately for your headline writers, there is no controversy here.  Our 2012 study (Meier et al. PNAS 2012) reported cognitive decline among individuals with a far more serious and far more long-term level of cannabis use. That is, we found cognitive decline in individuals followed up to age 38 who started cannabis use as a teen and who thereafter remained dependent on cannabis for many years as an adult. This new study is different; the two papers report about completely different doses of cannabis, and about participants 2 decades apart in age.  The new study reports cognitive test scores for individuals followed up to only age 17-20, fewer than half of whom had used cannabis more than 30 times, and only a fifth of whom used cannabis daily for > 6 months. This new study and our prior study agree and both report the same finding: no cognitive decline in short-term low-level cannabis users. The message from both studies is that short-term, low-level cannabis use is probably safer than very long-term heavy cannabis use. The big problem remains that for some teens, short-term low-level teenaged cannabis use leads onward to long-term dependence on cannabis when they become adults. That is what is cause for concern.”

“Imagine if  a study reported that teenagers drinking alcohol didn’t harm cognitive function by age 17-20, would you reasonably conclude from that study that persistent alcoholism for years cannot damage the cognitive function of adults in their late thirties? Hardly.”

Kevin Sabet

Author Kevin Sabet

More posts by Kevin Sabet