Adult Cannabis Use May Improve Cognitive Function


Using marijuana on a regular basis for three months resulted in improved task performance and executive brain functioning among a small group of study participants, according to a new findings from McLean Hospital and Harvard Medical School researchers.

The findings are supported by changes to the study participants’ brain activity, which the researchers assessed using before-and-after MRI imaging. The brain activity features a “normalization” pattern that closely mimics brain signals among healthy people, says the study.

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Additionally, study participants who turned to medical marijuana for one or more of a wide range of symptoms, from depression to pain, were less likely to use opioids and other substances that have been linked to overdose and addiction.

The study follows a prior look at the effects of medical marijuana from the same team of researchers that found improved cognitive tasks. The researchers note that a collection of other studies has not drawn the same conclusions, but their new findings again support a brain benefit.

“In our own recent pilot investigation, the only study to date to examine the impact of whole plant-derived [medical marijuana] products on cognitive performance, we found that [medical marijuana] patients did not demonstrate decrements in performance on measures of executive function,” they write. “In fact, patients generally demonstrated improved performance on a number of measures, particularly those assessing executive function.”

Shifting Attitudes on Marijuana

The study touches on a trend in America that continues to position medical marijuana as something other than a dangerous drug.

“Since societal attitudes toward marijuana (MJ) have generally warmed, an increasing number of individuals are turning to [medical marijuana] to help treat a variety of medical conditions, as patients often do not achieve full symptom alleviation with conventional medications and experience unwanted side effects,” write the researchers.

The researchers analyzed the results of a three-month period of marijuana use on 22 people. The study included a degree of independence among the participants, allowing them to choose how to consume the product.

Related: Marijuana May Reverse Brain Aging, Boost Memory: Study

“After completing pre-treatment assessments, patients began [medical marijuana] treatment at their discretion … patients selected their own products and determined their own treatment regimens,” they write.

All patients used marijuana regularly, from about one to two times per week on the low end to multiple times per day on the high end.

“Patients also indicated various routes of administration, including smoking and vaporizing flower, as well as use of oil and concentrates (vaporized and oral administration), tinctures, edibles and topicals,” describe the researchers.

Finding Cognitive Gains, Improved Scans

The 22 patients exhibited “notable changes in brain activation patterns” on MRI scans the researchers took prior to the study compared to those taken three months later.

When wrapping in self-reported data, the researchers also discovered that patients saw improvements “on measures of mood and quality of life,” along with improvements on ratings of depression, impulsivity and sleep.

Using the multi-source interference test (MIST), which measures the brain’s executive function and cognitive control, researchers also found that “patients exhibited improved task performance.”

The researchers are unsure as to why their findings show a discrepancy compared to other studies that haven’t linked marijuana use to improved brain function, but they speculate that most other studies include a population that’s heavily skewed toward adolescence, when a person’s neural networks are still forming.

The study appeared in the journal Frontiers in Pharmacology.

Related: Treating Chronic Pain With Cannabis Could Be Less Addictive Than Opioids