Weed and Dementia: Can THC Treat or Cause Dementia?

dementia and weed
By Rebecca Olmos Updated May 16th

Fact-checked by Alexandra Arnett, MS

Medically reviewed by Dr. Brian Kessler, MD

Dementia is a progressive disease characterized by a decline in mental functioning, particularly affecting memory. It is a broad diagnosis that encompasses several other conditions, like Alzheimer’s disease. 

Although anyone can develop dementia, it predominantly affects adults 65 and older. According to the CDC, 5.8 million people are diagnosed with dementia-related conditions, with 5.6 million being senior citizens. Still, about 200,000 of those diagnosed are under 65.

As legalization has developed across the country, there has been an increase in older adults using cannabis for various reasons. Many have questions regarding how cannabis may affect different ailments, including those related to dementia, so much so that the Alzheimer Society of Canada has even addressed it. 

A dementia diagnosis can be frightening, and treatment isn’t always clear or simple. While cannabis shows promise, understanding the intricacies of the effects associated with cannabis and their relationship with dementia symptoms is essential to making an informed treatment decision.

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What is Dementia?

Dementia is the steady deterioration of cognitive functioning. It happens when healthy neurons in the brain stop functioning properly and lose connection with the rest of the brain. These damaged areas of the brain are believed to occur heavily in the hippocampus, which affects learning and memory. 

The disease starts with mild symptoms, but as it progresses, thinking, remembering, and reasoning continuously decline enough to the point where they interfere with daily life. While dementia does not cause death directly, the ailments it triggers and the age at which most people develop the condition ultimately lead to death. Dementia mainly affects older adults over 65 but can develop at any time. 

This neurodegenerative diagnosis of dementia is an umbrella term. It includes other conditions, including: 

  • Alzheimer’s disease
  • Frontotemporal dementia
  • Lewy body dementia
  • Vascular dementia
  • Limbic-predominant age-related TDP-43 encephalopathy
  • Chronic traumatic encephalopathy (CTE)
  • Parkinson’s disease dementia
  • Creutzfeldt-Jakob disease
  • Huntington’s disease
  • Mixed dementia

Each of these diagnoses has symptoms specific to them. While there is no one cause of dementia, several factors can contribute to increased risk:

  • Age
  • High blood pressure
  • Diabetes
  • Excessive weight or obesity
  • Smoking
  • Repetitive head trauma
  • Excessive alcohol use
  • Sedentary lifestyle
  • Social Isolation
  • Depression

General signs and symptoms of dementia include:

  • Memory Loss
  • Difficulty concentrating
  • Struggling to complete daily tasks
  • Struggling to follow and engage in conversations
  • Confusion
  • Mood changes 
  • Hallucinating
  • Paranoia
  • Impulsivity
  • Mobility and balance issues

These symptoms can develop further or trigger other symptoms like insomnia

Can Weed Help Treat Dementia Symptoms?

weed and dementia

Cannabis interacts with the body through the endocannabinoid system (ECS), affecting various functions throughout the body and its neurological systems. Since cannabis can potentially deliver a wide variety of therapeutic benefits, it’s understandable that people wonder how it may impact diseases like dementia and its symptoms. 

While there is no cure for dementia, prescription medications, like cholinesterase inhibitors and memantine, can be taken to help relieve symptoms. Other treatment includes occupational therapy, modifying the individual’s environment, and simplifying tasks. 

When it comes to cannabis and dementia, there are limited analyses that discuss the two simultaneously. One review of the few studies available found that cannabis may be beneficial in treating some of the symptoms that develop after diagnosis, like mood changes and sleep difficulties.1 However, the researchers disclose that the quality of those studies where positive results occurred was lower than those that showed no correlation at all between symptoms of dementia and cannabis use. 

Another review of the literature also found little to no correlation between cannabis and improved cognitive functioning in those with dementia.2 It’s worth noting that many of the studies included in the assessment were done on mice. A separate study conducted on a small sample of human participants did find a positive correlation between THC and dementia symptoms, where irritability and level of caregiver distress both improved with cannabis consumption.3 

Some individual components of cannabis have been studied in their ability to aid dementia symptoms. Pinene, a terpene that is found in many cannabis cultivars, is known to be a neuroprotectant and, in one study on rats, was found to prevent neuroinflammation in the hippocampus, which is a critical player in the development of diseases related to dementia.4

It is also understood that traumatic brain injury may trigger the development of dementia. Some studies show that cannabis may help alleviate symptoms of TBIs like concussions, but further research is still needed.

In general, cannabis can provide a relaxing experience that can alter an individual’s mood, which is another reason people may consider turning to cannabis for the treatment of dementia and its symptoms. 

One study looked into this relationship and found no definitive conclusion because of the varying dosages distributed to patients. However, the researchers did acknowledge that some findings suggested ratioed THC and CBD or just CBD alone helped reduce agitation in dementia patients.5

With all the conflicting findings in these limited studies, it makes sense that cannabis isn’t a recommended form of treatment by dementia specialists. The small amount of evidence that supports cannabis’ ability to alleviate the disease’s symptoms will hopefully prompt the medical research community to study the relationship between cannabis and dementia further.

Can Weed Cause Dementia?

Can Weed Cause Dementia

There’s a respectable amount of research done on how cannabis affects the brain in a variety of different capacities, and it is well-documented that consumption can affect memory and the ability to complete tasks. So it makes sense that some people might wonder: can weed cause dementia?

The impact on memory happens because THC affects the hippocampus, which is responsible for memory and processing details. Although cannabis may only affect memory in the short term, science is still learning about the impact of prolonged heavy cannabis use on the brain. 

One study suggested that extended cannabis use does not appear to have any long-term effects on the hippocampus,6 but others have conflicting findings.7 Although there have been promising insights into cannabis and dementia, more research is needed.

If you or someone you care for with dementia is curious about cannabis treatment, consult your doctor. Since THC and dementia affect similar parts of the brain, cannabis consumption is only recommended for dementia sufferers with a doctor’s recommendation and under appropriate medical guidance. 

What About CBD and Dementia?

CBD and Dementia

Cannabidiol, better known as CBD, is another cannabinoid found in generous quantities in the cannabis plant, especially hemp varieties. This component doesn’t cause the same intoxicating effects as THC but has many therapeutic benefits. While CBD does interact with the hippocampus like THC, it increases blood flow rather than harm its functioning.8

CBD has also been studied for its neuroprotective properties9 and how it may aid in recovering TBIs.10 One study specifically examined cannabis users and their hippocampus functioning. The results showed that those who consumed isolated THC (with no cannabidiol) showed more damage than those who consumed high CBD or abstained from usage altogether.11

These promising findings are why many people have started to inquire about using cannabis – and CBD, specifically – as a potential treatment for conditions relating to the brain, like dementia. Regardless, before beginning any sort of cannabis treatment for dementia or its symptoms, consult with a doctor. 

Precautions When Using Weed for Dementia

Weed for Dementia

If you’re considering using cannabis to treat dementia or its symptoms, it’s crucial to speak with a medical professional first and consider any additional medicine you may be taking. Then, if cannabis is discussed and recommended for treatment, a few factors should be considered. 

While there are limited studies, some suggest that THC may not be the best cannabinoid for dementia patients because it can adversely affect the same area of the brain the disease affects. CBD, however, has been looked at for the treatment of dementia because of its neuroprotective properties. That said, products with both CBD and THC have shown the potential to aid in symptoms of dementia related to mood. 

There is no standard recommended cannabis dosage for dementia patients. Still, since THC can cause intoxicating effects, starting with CBD-rich products or more balanced options may be best. Start with a small dosage, which may depend on your tolerance level, comfort level, and other medications in your routine. Take note of how you feel and adjust your dosage as needed and with the support of a qualified medical marijuana doctor. 

There is also no recommended mode of consumption for dementia patients, but methods like tinctures, capsules, or edibles may cause less damage to the body than traditional inhalation methods like smoking or vaping

Some medical cannabis states, like Arizona, list dementia as a qualifying condition for cannabis treatment. Regardless of your state’s qualifying conditions, purchase cannabis (or hemp) products from a trusted licensed retailer to ensure they are properly tested for purity and potency.

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How to Decrease the Chances of Dementia

There is no known cause or cure for dementia. It’s a progressive disease that tends to develop in adults older than 65. The best thing you can do is help keep your mind and body healthy. This includes:

  • Regular physical activity
  • Eating healthy
  • Refrain from smoking (edibles are a common alternative)
  • Refrain from alcohol
  • Staying mentally active
  • Socialize

Maintaining an overall healthy, active, and balanced lifestyle is the best way to reduce your risk of developing dementia or its related diseases. 

More research is needed to understand how long-term cannabis use affects the brain in later life. If you’re a cannabis consumer, it may be most reasonable to supplement dosages of CBD into your routine or practice taking regular tolerance breaks to help the brain and hippocampus stay healthy. 


1. PMC, Europe. “Europe PMC.” Europepmc.org, europepmc.org/article/nbk/nbk546328?report=printable&client=bot.

2. Aso E, Andrés-Benito P, Ferrer I. Delineating the Efficacy of a Cannabis-Based Medicine at Advanced Stages of Dementia in a Murine Model. J Alzheimers Dis. 2016;54(3):903-912. doi:10.3233/JAD-160533

3. Shelef A, Barak Y, Berger U, et al. Safety and Efficacy of Medical Cannabis Oil for Behavioral and Psychological Symptoms of Dementia: An-Open Label, Add-On, Pilot Study. J Alzheimers Dis. 2016;51(1):15-19. doi:10.3233/JAD-150915

4. Khan-Mohammadi-Khorrami MK, Asle-Rousta M, Rahnema M, Amini R. Neuroprotective effect of alpha-pinene is mediated by suppression of the TNF-α/NF-κB pathway in Alzheimer's disease rat model. J Biochem Mol Toxicol. 2022;36(5):e23006. doi:10.1002/jbt.23006

5. Mueller A, Fixen DR. Use of Cannabis for Agitation in Patients With Dementia. Sr Care Pharm. 2020;35(7):312-317. doi:10.4140/TCP.n.2020.312

6. Koenders L, Lorenzetti V, de Haan L, et al. Longitudinal study of hippocampal volumes in heavy cannabis users. J Psychopharmacol. 2017;31(8):1027-1034. doi:10.1177/0269881117718380

7. Meier MH, Caspi A, R Knodt A, et al. Long-Term Cannabis Use and Cognitive Reserves and Hippocampal Volume in Midlife. Am J Psychiatry. 2022;179(5):362-374. doi:10.1176/appi.ajp.2021.21060664

8. Bloomfield MAP, Green SF, Hindocha C, et al. The effects of acute cannabidiol on cerebral blood flow and its relationship to memory: An arterial spin labelling magnetic resonance imaging study. J Psychopharmacol. 2020;34(9):981-989. doi:10.1177/0269881120936419

9. Bhunia S, Kolishetti N, Arias AY, Vashist A, Nair M. Cannabidiol for neurodegenerative disorders: A comprehensive review. Frontiers in Pharmacology. 2022;13. doi:https://doi.org/10.3389/fphar.2022.989717

10. Aychman MM, Goldman DL, Kaplan JS. Cannabidiol’s neuroprotective properties and potential treatment of traumatic brain injuries. Frontiers in Neurology. 2023;14. doi:https://doi.org/10.3389/fneur.2023.1087011

11. Yücel M, Lorenzetti V, Suo C, et al. Hippocampal harms, protection and recovery following regular cannabis use. Transl Psychiatry. 2016;6(1):e710. Published 2016 Jan 12. doi:10.1038/tp.2015.201

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.

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