Cannabis and Alzheimer’s: Can Weed Cause Alzheimer’s Disease?

Alzheimer’s is a neurodegenerative condition where the brain shrinks and its cells die. Alzheimer’s disease is the leading cause of dementia in older adults, causing a progressive decline in memory, thinking, and other vital cognitive tasks. Eventually, the person may be unable to recognize their surroundings or hold a conversation.

In 2023, the Alzheimer’s Association found that 6.7 million Americans aged 65 and older have Alzheimer's. Even though it primarily affects older adults, a small number of people will develop early-onset Alzheimer’s disease in their 40s or 50s.¹

The term “Alzheimer’s disease” was first used in 1910 by Emil Kraepelin, the teacher of Alois Alzheimer. After observing a patient for five years and examining her brain upon her death, Alzheimer's linked symptoms of progressive cognitive decline to physical changes in the brain - what we now know to be a hallmark of Alzheimer’s disease.²

Much of what causes Alzheimer’s is still a mystery to scientists. Recently, experts published a study on over 1,000 brain tissues from people with and without Alzheimer's. They found that by measuring protein levels, they were able to observe similar large-scale changes across the brain samples with Alzheimer’s, a new development that will help researchers develop new tests and treatments for Alzheimer's.³

What Causes Alzheimer’s Disease?

Alzheimer’s disease happens when there is an abnormal amount of protein build-up in the brain, damaging fundamental brain cells and eventually causing them to die. It is estimated that 70% of Alzheimer’s cases are due to genetics. Different gene mutations MAY cause early-onset and late-onset Alzheimer’s. These mutations can lead to an early development of the plaque protein build-up deposits in the brain for early-onset Alzheimer’s.

In late-onset Alzheimer’s, the research is not clear on how the gene mutation causes the disease, but the protein the gene encodes for has neuroprotective effects. Another potential genetic link for late-onset Alzheimer’s may lie within the TREM2 gene, which is responsible for the modulation of inflammatory responses in the central nervous system. It is suggested that an impairment in the receptor the gene encodes for could promote the development of plaque in the brain.⁴

Other risk factors for the development of Alzheimer’s include;

• Cerebrovascular diseases (i.e., stroke)
• Hypertension
• Type 2 diabetes
• Obesity
• Elevated cholesterol
• Widowed marital status
• Stress
• Depression
• Lack of sleep
• Smoking⁴

Signs & Symptoms of Alzheimer’s Disease

People who have Alzheimer’s disease may experience one or more of the following common symptoms:

• Disruptive changes in short-term memory (the most common warning sign of Alzheimer's)
• Decreased ability for logical thinking and complicated tasks
• A decline in language skills
• Decreased spatial awareness
• Behavioral and personality changes

While the above signs of Alzheimer's are common, symptoms are usually dependent on what stage of the disease the individual is in:

1. Preclinical stage: The brain changes that lead to Alzheimer’s disease begin years before a person shows any signs of the disease. This stage is usually only referenced in research since it cannot be diagnosed in a living person.

2. Mild, early stage: The person may have some mild forgetfulness and problems with concentration, and they might even be aware of them. They may still be able to take care of themselves without assistance.

3. Moderate, middle stage: This stage is the longest and can last for many years. Problems with memory, concentration, and complex tasks worsen, and the person may experience personality, behavioral, and physical changes. They might need help remembering where they are and may need help with daily activities. 

4. Severe, late stage: Symptoms continue to grow in severity. The individual may lose some physical abilities, including walking, sitting, eating, and controlling their bladder and bowels. Often, the person is unable to communicate except for a few words or phrases. Usually, they will need help for all activities and are more prone to infection.

Can Cannabis Help Alleviate Symptoms of Alzheimer’s Disease?

Many studies investigate marijuana and Alzheimer’s disease, but the evidence is conflicting. Even so, some states have already approved Alzheimer’s disease as a qualifying condition for medical cannabis.

• Preliminary data from a 2017 in vivo study shows that CBD and CBD+THC may improve the growth of nervous tissue and reduce damaging inflammation regarding Alzheimer's.⁵ In vivo studies mentioned in a 2019 review indicated that, in the case of memory problems from dementia, the combination of THC + CBD treatment may be more beneficial than THC or CBD alone.⁶ Both studies are limited because their results must be replicated in human studies, but they support further research.

• The Alzheimer Society of Canada reports that although no studies have shown cannabis benefits Alzheimer’s disease, they launched a pilot study to investigate its effects on agitation caused by Alzheimer's. In 2019, they reported that nabilone, synthetic THC, showed potential to reduce agitation and improve overall behavioral symptoms in their 14-week trial.

• A 2022 review investigated cannabinoids and their effect on Alzheimer’s disease. Researchers concluded combinations of THC and CBD have apparent neuroprotective properties concerning Alzheimer's in the early stages and other neurodegenerative conditions, making them potential candidates for new drug therapies.⁷

• A 2022 review concluded that while cannabis seems to cause adverse effects on cognition, there is high-quality evidence that this effect is lessened with lower doses of THC. More long-term studies are needed to generate definitive evidence.⁸

No medication or substance has been shown to reverse or halt the progression of Alzheimer’s disease. The research surrounding cannabis indicates that there may be a potential neurological benefit to some cannabinoids. Still, these findings are limited by the early stage of the studies, the lack of human trials, and inconsistent study methodologies. 

If you have Alzheimer’s disease or are a caretaker for someone with Alzheimer's, consult a healthcare provider and check your state’s laws before introducing cannabis. Medical marijuana may not be available in all states for someone with Alzheimer’s. 

Cannabis may be beneficial in some cases, but results are not guaranteed, and the psychoactivity associated with cannabis may be problematic for someone already disoriented from Alzheimer’s disease. It is also possible that cannabis may interact differently in a brain affected by Alzheimer's compared to a healthy brain. 

If you are planning to use cannabis, stick to products that are CBD-rich, with low amounts of THC, or contain only CBD. While smoking dried cannabis flower may not be possible or advisable for someone with dementia caused by Alzheimer's, tinctures, capsules, oral sprays, edibles, and teas may be best. These products are easy to dose and administer to someone who cannot do it themselves. Products containing other non-psychoactive cannabinoids for dementia, like CBG, may also be used.

Legality and Doctor’s Recommendation

To determine if your state considers Alzheimer’s a qualifying condition for medical marijuana, check out our Laws & Regulations section for the medical cannabis rules for your state.

If you find that your state recognizes Alzheimer’s or its symptoms as a qualifying medical condition, you can seek a doctor’s recommendation to get your medical cannabis card in your state.

How NuggMD Can Help

NuggMD is the nation's leading medical marijuana technology platform, serving patients in over half the United States. We’ve connected more than 1,300,000 patients with their new medical marijuana doctors face-to-face via our state-of-the-art telemedicine platform. 

We believe that every human being has the right to explore the benefits of medical cannabis and are fully committed to helping each patient explore all their options in their journey to wellness. For further information on whether you qualify for medical cannabis, select your state.

Frequently Asked Questions About Cannabis & Alzheimer’s Disease

Is using cannabis with Alzheimer’s disease a good idea?

There is not enough definitive evidence for the detriment or benefit of cannabis on Alzheimer’s disease. At the same time, some states have approved Alzheimer's as a qualifying condition for medical marijuana. According to a 2019 study, a synthetic version of cannabis may be able to reduce agitation in people with Alzheimer’s disease.

Is there a cannabis-based Alzheimer’s medicine?

No cannabis-based medications have been developed for the treatment of Alzheimer’s disease or its symptoms. Cannabinoid blends of CBD and THC demonstrate therapeutic potential in animal models, but more research is needed.

Are CBD and dementia a bad combination?

While some experts believe that cannabis may have a negative effect on cognition, more research is needed to determine whether this is the case. Low doses of THC may be the way to avoid these adverse effects. Use caution when considering THC, especially in the long term, if you are at risk for dementia or Alzheimer’s.

Resources

1. Mendez MF. Early-onset Alzheimer Disease and Its Variants. Continuum (Minneap Minn). 2019;25(1):34-51. doi:10.1212/CON.0000000000000687
2. Yang HD, Kim DH, Lee SB, Young LD. History of Alzheimer's Disease. Dement Neurocogn Disord. 2016;15(4):115-121. doi:10.12779/dnd.2016.15.4.115
3. Johnson ECB, Carter EK, Dammer EB, et al. Large-scale deep multi-layer analysis of Alzheimer’s disease brain reveals strong proteomic disease-related changes not observed at the RNA level. Nature Neuroscience. 2022;25(2):213-225. doi:https://doi.org/10.1038/s41593-021-00999-y
4. Silva MVF, Loures C de MG, Alves LCV, de Souza LC, Borges KBG, Carvalho M das G. Alzheimer’s disease: risk factors and potentially protective measures. Journal of Biomedical Science. 2019;26(1). doi:https://doi.org/10.1186/s12929-019-0524-y
5. Watt G, Karl T. In vivo Evidence for Therapeutic Properties of Cannabidiol (CBD) for Alzheimer’s Disease. Frontiers in Pharmacology. 2017;8. doi:https://doi.org/10.3389/fphar.2017.00020
6. Kim SH, Yang JW, Kim KH, Kim JU, Yook TH. A Review on Studies of Marijuana for Alzheimer’s Disease - Focusing on CBD, THC. Journal of Pharmacopuncture. 2019;22(4):225-230. doi:https://doi.org/10.3831/KPI.2019.22.030
7. Coles M, Steiner-Lim GZ, Karl T. Therapeutic properties of multi-cannabinoid treatment strategies for Alzheimer’s disease. Frontiers in Neuroscience. 2022;16. doi:https://doi.org/10.3389/fnins.2022.962922
8. Wieghorst A, Roessler KK, Hendricks O, Andersen TE. The effect of medical cannabis on cognitive functions: a systematic review. Systematic Reviews. 2022;11(1). doi:https://doi.org/10.1186/s13643-022-02073-5

The information in this article and any included images or charts are for educational purposes only. This information is neither a substitute for, nor does it replace, professional legal advice or medical advice, diagnosis, or treatment. If you have any concerns or questions about laws, regulations, or your health, you should always consult with an attorney, physician or other licensed professional.