Marijuana for Alzheimer’s Disease

Cannabis therapy might reverse dementia symptoms by reducing the pathology

Posted Nov 07, 2014

Proof that smoking marijuana can slow the advance of Alzheimer’s disease has not previously existed. The evidence has been quite circumstantial and often seemed rather secondary to the known actions of cannabinoids in the brain.  Things have changed recently.

Our human brain produces its own endogenous marijuana-like chemicals. One of them is call 2-AG and is the most abundant of the endogenous marijuana-like chemicals. 2-AG has been repeatedly shown to protect the brain from many different harmful toxins and mutant proteins.  2-AG is destroyed by an enzyme called MAGL. Selectively inhibiting MAGL leads to elevated levels of 2-AG in the brain.  A recent study demonstrated that elevated levels of 2-AG causes a suppression in the production of a toxic protein, beta-amyloid, that is one of the hallmarks of Alzheimer’s disease (AD) and is thought to contribute to the death of cells in the brain as the dementia symptoms progress.

This discovery by a group of neuroscientists at Louisiana State Medical School is important because it suggests that stimulation of the brain’s endogenous marijuana system might actually reduce the symptoms of the dementia.  My own research has also demonstrated the positive effects of stimulation of the endogenous cannabinoid neural system in the aging brain. This new report outlines a new group of cellular targets for drugs that might actually stop the progression of the pathology underlying AD.

During the past few years scientists have found that activating the brain’s marijuana systems may offer protection from the consequences of stroke, chronic pain, migraines and psychic pain due to separation or loss.  Surprisingly, marijuana may also protect against some aspects of age-associated memory loss that leads to AD. Ordinarily, we do not view marijuana as being good for our brain.  How could a drug that clearly impairs memory while people are under its sway protect their brains from the consequences of aging?  The answer likely has everything to do with the way that young and old brains function and a series of age-related changes in brain chemistry that might be initiated by a build-up of beta-amyloid.  When we are young, stimulating the brain’s marijuana receptors interfere with making memories.  However, later in life, marijuana might actually help your brain, rather than harm it. If you’d like to know more about this topic, please watch my TED talk.

© Gary L. Wenk, Ph.D. Author of Your Brain on Food (Oxford University Press)

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