Cannabis & dementia... what you need to know

Published: Mar 09, 2018

With the legalization of marijuana expected to take effect this summer, many people are interested in learning more about whether or not cannabis-derived products could be beneficial for those with dementia. Alzheimer Society of Calgary’s team has received an increasing number of questions on this topic. As a result, we’ve put together a summary to improve your understanding – based on what we know so far.

First, it’s helpful to clarify some terms. Cannabis is the formal name of the plant often referred to as ‘marijuana.’ Many different types of products can be derived from parts of the cannabis plants, including hemp (sterilized cannabis seeds, the fibre extracted from the stems).  What is frequently referred to as ‘marijuana’ are the viable seeds, leaves and/or flowers of the cannabis plant.

Cannabis plants contain several active compounds, collectively referred to as cannabinoids, in varying amounts. The best-known of these compounds is THC (tetrahydrocannabinol) and CBD (cannabidiol).  THC is the compound responsible for many of the popularly associated effects of cannabis, including a sense of euphoria or “high.”  Strains of cannabis with large concentrations of THC are often prescribed to those suffering from severe nausea during chemotherapy treatment, along with those who have lack of appetite due to HIV/AIDS or other medical conditions. 

Alternatively, CBD does not appear to have the same intoxicating effects as THC, so it is often used in an oil-based form to treat chronic health conditions, especially childhood epilepsy unresponsive to medical treatment.  There is some evidence that CBD may be useful for a variety of other medical conditions, including severe chronic pain, cancer-associated pain, anxiety and depression.

Different cannabis-derived products have varying concentrations of these active compounds.  For example, many strains of hemp have extremely low levels of THC, one reason that hemp is not a legally-regulated substance.

Several studies have examined both the effects of THC and CBD on dementia, while others have looked at the effect of cannabinoids in general. 

The few clinical trials that have taken place on the effects of cannabis for people affected by dementia have looked at whether the drug can help manage some symptoms of the condition. Symptoms such as agitation and aggression could, in theory, be counteracted by the effects of cannabis or its components. 

A few small clinical trials have assessed the effects of cannabinoids, including THC and synthetic cannabinoids such as nabilone, on behavioural symptoms of dementia. However, scientific reviews have found that the trials and studies so far have generally been small or of low quality, making it difficult to come to an informed conclusion. 

No studies or trials have looked into the effects of cannabis or its components on the underlying causes of Alzheimer's disease in people. And very often, experimental drugs that yield positive results in lab studies and animal studies perform poorly in human trials.

It is also worth noting that many of these studies have involved a particular component of cannabis in isolation. Even if one component is found to influence dementia risk, it doesn't necessarily mean that taking cannabis would have the same effect. There is also a large amount of variation in the levels of THC and CBD in different strains of the plant so the effects could depend on the type of cannabis used. 

Ultimately, we must remember that research in this area is still in its infancy.  Therefore, further research, large-scale clinical trials, and time to create a body of evidence for the use of these substances are all needed before cannabis-derived products could be recommended for the treatment of Alzheimer’s disease and other dementias.

It is important to remember that cannabis should not be used if you have serious liver, kidney, heart, or lung disease, or if you have a personal or family history of a serious mental illness such as schizophrenia, bipolar disorder, psychosis or depression. Cannabinoids can interact with several medications including sleeping pills, tranquillizers, pain medications, allergy/cold medications, some antidepressants, some heart medications, some stomach-acid medications etc. and cause serious adverse reactions. Please consult your family physician before you start taking cannabis.

And as Neel Nabar, co-author of one of the studies mentioned above, says, “It’s important to keep in mind that just because a drug may be effective doesn’t mean it can be safely used by anyone. However … [eventually] findings may lead to the development of related compounds that are safe, legal, and useful in the treatment of Alzheimer’s disease.”

For further information, please contact us.