Can Tetrahydrocannabinol (THC) Help Reduce Alzheimer's?

Tetrahydrocannabinol (THC), the compound responsible for marijuana’s psychoactive effects, may offer hope for treating Alzheimer’s disease, at least according to a study on mice. 1 Rodents with a disease similar to Alzheimer’s were given a synthetic form of THC, which resulted in fewer lost brain cells, 20 percent less sticky plaques in the brain (which are linked to Alzheimer’s) as well as a boost in memory.

In fact, Alzheimer’s mice given THC did as well on memory tests as healthy mice, while those given a placebo lost some of their memory. 2 The study was presented at the Society for Neuroscience 2018 meeting in San Diego, California, and hasn’t yet been published, but it raises hope that a cannabis-based treatment could prove to be therapeutic for Alzheimer’s.

THC Improves Memory in Alzheimer’s Mice

The study was interesting in that it found THC — but not cannabidiol (CBD) — to be beneficial on memory function and neuron loss in mice with Alzheimer’s. Cannabidiol is the nonpsychoactive component of cannabis, which has previously been found to offer many benefits for pain relief, seizures and other health conditions.

Cannabinoids interact with your body by way of naturally occurring cannabinoid receptors embedded in cell membranes throughout your body. There are cannabinoid receptors in your brain, lungs, liver, kidneys, immune system and more; the therapeutic (and psychoactive) properties of marijuana occur when a cannabinoid activates a cannabinoid receptor.

Your body also has naturally occurring endocannabinoids similar to THC that stimulate your cannabinoid receptors and produce a variety of important physiologic processes.

So, your body is actually hard-wired to respond to cannabinoids through this unique cannabinoid receptor system. It’s likely that both THC and cannabidiol exert their effects via your body’s endocannabinoid system. According to the researchers: 3

“Endocannabinoid signaling has been demonstrated to be involved in numerous processes, including brain development, memory formation, motor control, neuroinflammation, excitotoxicity and oxidative stress.

Furthermore, several in vitro studies showed that cannabinoids reduce Aβ [amyloid beta]-induced neurotoxicity as well as cell death and facilitate neurogenesis. It could also be demonstrated that cannabinoids stimulate the removal of intraneuronal Aβ in vitro.

… Cannabinoid-treatment in … mice show the potential of the endocannabinoid system as a therapeutic target in Alzheimer’s disease influencing the molecular signature and improving memory deficits. Our findings reinforce a cannabis-based medicine as a potential AD [Alzheimer’s disease] therapy.”

THC May Reverse Brain Aging

Researchers of the featured study cautioned that people should not take the results to mean they should light up in order to preserve their brain health. When healthy mice were given THC, they actually had learning difficulties. However, previous research on mice has also found THC to be beneficial for brain health.

One such study, published in Nature Medicine, found that a low dose of THC reversed the age-related decline in cognitive performance of mice aged 12 and 18 months. 4 The dose was small enough to avoid any psychoactive effects, yet strong enough to reverse the loss of performance in the old animals (mice typically live to be 2 years old).

Further, gene activity and the molecular profile in the brain tissue of THC-treated mice were that of much younger animals. Specifically, neurons in the hippocampus grew more synaptic spines — points of contact necessary for communication between neurons.

Previous research has also shown that the brain ages much faster in mice who do not have functional receptors for THC, suggesting THC may be involved in the regulation of the aging process. 5 The next logical step would be to test marijuana and its compounds in people with Alzheimer’s, but political red tape is holding up the scientific process.

Speaking to NPR, cannabis researcher Jamie Roitman, an associate professor of psychology at the University of Illinois at Chicago, explained, “‘There are just no venues to do it.” NPR continued, “Getting approval for any study involving people and compounds related to marijuana is ‘very difficult,’ she said, despite the fact that the drug is now legal in many states.” 6

Still, cannabis therapeutics are at the forefront of the future of neurology, according to researchers writing in Frontiers in Integrative Neuroscience, and because they work via multiple mechanisms it’s possible they could be useful not only for Alzheimer’s but also for Parkinson’s disease, brain tumors, epilepsy and traumatic brain injury. They noted: 7

“The inherent polypharmaceutical properties of cannabis botanicals offer distinct advantages over the current single-target pharmaceutical model and portend to revolutionize neurological treatment into a new reality of effective interventional and even preventative treatment.”

What Else Is Medical Marijuana Good For?

Cannabinoid receptors play an important role in many body processes, including metabolic regulation, cravings, pain, anxiety, bone growth and immune function. "Medical marijuana" refers to the use of the whole, unprocessed marijuana plant or its extracts for medicinal purposes. Through traditional plant breeding techniques and seed exchanges, growers have started producing cannabis plants that have higher levels of CBD and lower levels of THC for medical use.

Since the 2018 election, which resulted in a few states approving various forms of marijuana, medical cannabis is now legal in 33 U.S. states, while recreational use is legal in 10 states and Washington, D.C. 8 Most of the areas where medical cannabis is legal permit its use under certain medical circumstances only, and some allow CBD oils or pills only. What are people using it for? Pain and anxiety are top uses, but there is also potential for its use as a cancer treatment.

For example, Harvard researchers found THC cuts tumor growth in lung cancer while significantly reducing its ability to spread. 9 Even in cases of glioblastoma, one of the deadliest types of cancer, cannabinoids may help, as they’ve been shown to inhibit the invasiveness of glioblastoma tumors and improve survival of glioblastoma patients. 10 In addition, cannabinoids have shown promise for a variety of medical uses, including: 11

Multiple sclerosis


Irritable bowel syndrome

Huntington’s disease


Eye diseases

Chemotherapy-associated nausea and vomiting

Inflammatory and neuropathic pain

Post-traumatic stress disorder

Anxiety disorders

Interestingly, it’s likely that both TCH and CBD may have a beneficial role in health. One study even found that CBD may buffer some of the psychoactive effects of THC and the two compounds may offer greater therapeutic results when administered together than alone. 12

If you’re considering the use of medical marijuana, and you live in a state where it’s legal, you can get a recommendation for a medical cannabis card from your physician, then join a collective, which is a group of patients that can grow and share cannabis medicines with each other. By signing up as a member, you gain the right to grow and share your medicine.

There are different ways to administer medical marijuana, ranging from inhalation, vaporization and smoking to sublingual (under the tongue), oral ingestion and topically. The best form for you will depend on your medical needs, so ideally work with an experienced physician to determine the best route of administration and dosage.

Keep in mind that although medical marijuana may seem like a new or trendy treatment, its medicinal properties have been valued for thousands of years, including by Traditional Chinese Medicine, in India and by ancient Egyptians, Persians and Greeks.

Coffee: Another Natural Compound That Benefits Alzheimer’s

Along with marijuana, many other natural substances may also contain properties that inhibit Alzheimer’s, and coffee is no exception. “Coffee consumption has been correlated with a decreased risk of developing Alzheimer's disease (AD) and Parkinson's disease (PD), but the mechanism by which coffee may provide neuroprotection in humans is not fully understood,” researchers explained. 13

It’s previously been suggested that the caffeine in coffee may be responsible for many of its beneficial effects, but a new study revealed similar beneficial properties for the brain among both caffeinated and decaffeinated varieties. The distinguishing factor appeared to be the type of roast, with dark roast coming out on top.

A compound called phenylindane is formed when coffee beans are roasted, with higher quantities found in darker roasts. Phenylindane is also neuroprotective, as it inhibits amyloid-beta and tau aggregation, both of which are implicated in Alzheimer’s. Researchers plan to look further into whether phenylindanes are able to enter the bloodstream and cross the blood-brain barrier.

Also similar to marijuana, coffee consumption has been linked to a lower risk of glioma brain tumor, such that people in the top category of coffee consumption were 91 percent less likely to develop glioma compared with those in the bottom category. 14

Drinking one to two cups of coffee daily has also been shown to lower your risk of Alzheimer's disease and other forms of dementia, cognitive decline and cognitive impairment compared to drinking less than one cup. 15

Top Tips for Lowering Your Alzheimer’s Risk

Alzheimer’s disease has grown to be one of the most pressing and tragic public health issues facing the U.S. With the number of people affected expected to triple by 2050, the Alzheimer’s Association estimates that by midcentury someone in the U.S will develop Alzheimer’s disease every 33 seconds. 16

Medical marijuana may one day prove to be a useful tool for Alzheimer’s prevention and treatment, but it’s not yet widely available for most people. Many other strategies that get to the root of the disease are available right now, however, like exercise to increase brain-derived neurotropic factor (BDNF), stress reduction, optimizing your sleep, which is critical for cognitive function, and nutritional support.

Important nutrients include animal-based omega-3 fats, magnesium, vitamin D and fiber. For instance, seniors with severe vitamin D deficiency may raise their risk for dementia by 125 percent, and vitamin D deficiency is associated with a substantially increased risk of all-cause dementia and Alzheimer's disease. 17 Have your levels tested and maintain a blood level of 60 to 80 ng/ml year-round.

As for omega-3, high intake of the omega-3 fats EPA and DHA help by preventing cell damage caused by Alzheimer's disease, thereby slowing down its progression and lowering your risk of developing the disorder. Ideally, get an omega-3 index test done once a year to make sure you’re in a healthy range. Your omega-3 index should be above 8 percent and your omega 6-to-3 ratio between 0.5 and 3.0.

I also recommend a cyclical or targeted ketogenic diet to help you optimize your health by converting from burning carbohydrates for energy to burning fat as your primary source of fuel. You can learn more about this approach to improving your mitochondrial function, which is also at the heart of Alzheimer’s disease, in my book, " Fat for Fuel ."

One of the most common side effects of being a sugar-burner is that you end up with insulin and leptin resistance, which is at the root of most chronic disease. Intermittent fasting is another powerful tool to jump-start your body into remembering how to burn fat and repair insulin/leptin resistance. Taken together, these lifestyle strategies remain your best defense to avoid dementia and keep your brain health strong.

For more information, be sure to pick up a copy of " The End of Alzheimer's: The First Program to Prevent and Reverse Cognitive Decline ," by Dr. Dale Bredesen, director of neurodegenerative disease research at the University of California, Los Angeles (UCLA) School of Medicine. It’s packed with tools for both prevention and treatment.