Marijuana may increase risk of Alzheimer’s, study suggests

November 30, 2016 Providence Health Team

As more states legalize the recreational use of marijuana, a new study suggests the drug contributes to abnormally low flows of blood to the brain, especially to the region that plays a key role in Alzheimer’s disease.

Researchers found the lowest flow of blood to the hippocampus, which is the brain’s key memory and learning center. That finding suggests marijuana users are more vulnerable to Alzheimer’s disease than are non-users, they said.

“As a physician who routinely sees marijuana users, what struck me was not only the global reduction in blood flow in the marijuana users brains, but that the hippocampus was the most affected region due to its role in memory and Alzheimer’s disease,” said Elisabeth Jorandby, M.D., of the Costa Mesa, Calif.,-based Amen Clinics and co-author of the study. “Our research has proven that marijuana users have lower cerebral blood flow than non-users.”

Added Jorandby: “This work suggests that marijuana use has damaging influences in the brain – particularly regions important in memory and learning and known to be affected by Alzheimer’s.”

Shifting political winds

Voters around the country have shown an increasing willingness to legalize or decriminalize the use of marijuana. Already, 26 states and the District of Columbia allow people to use marijuana legally for either medical or personal purposes, or both. This fall, three more states passed measures to permit legal use.

Marijuana is sometimes prescribed to treat:

  • Pain, especially related to nerve damage
  • Nausea that accompanies chemotherapy
  • Muscle spasms related to multiple sclerosis
  • Seizures
  • Crohn’s disease
  • Pain, weight loss and poor appetite related to a chronic illness

“There is more public support for marijuana law reform than ever before with new polls showing more than half the country is in favor of legalizing marijuana,” says the Drug Policy Alliance, an advocacy group. “DPA believes marijuana should be removed from the criminal justice system and regulated like alcohol and tobacco.”

The findings of the new study, along with the Norwegian study, will surely enter into the policy debate.

“Open use of marijuana, through legalization, will reveal the wide range of marijuana's benefits and threats to human health,” said George Perry, M.D., editor of the Journal of Alzheimer’s Disease.  The Amen Clinics study, he said, “indicates troubling effects on the hippocampus that may be the harbingers of brain damage.”

Further resources

Providence has services for those interested in the medical effects of marijuana, from treating addictions to dealing with dementia. You can find a Providence provider here.

Here is the report on the blood-flow study: “New study shows marijuana users have low blood flow to brain.” And here is the study itself: “Discriminative Properties of Hippocampal Hypoperfusion in Marijuana Users Compared to Healthy Controls: Implications for Marijuana Administration in Alzheimer’s Dementia.”

Here is the report on a Norwegian study: “Cannabis abuse possible cause of psychosis.”

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