Cannabis and Alzheimer’s Disease: What You Need to Know

There are presently more than 55 million people with some form of dementia, with around 10 million new cases diagnosed yearly. Alzheimer's disease—a condition that causes dementia—is highly debilitating for the sufferer and also devastating for families, who have to watch as the person they know slowly disappears in front of them.

Many people have heard of Alzheimer's, but its causes remain a mystery. Here we look at what science knows about Alzheimer's, and whether cannabis may be of any benefit to patients.

What Is Alzheimer's Disease?

Alzheimer's most commonly affects those aged 65 or over, although it can also occur in younger people. Alzheimer's affects an estimated 1 in 14 people over 65, and 1 in every six people over 80. Though the exact causes of Alzheimer's are still not fully understood, several factors indicate increased risk. These include:

• Family history of Alzheimer's
• Advanced age
• Lifestyle aspects and ailments associated with cardiovascular disease
• Untreated mental health issues, such as depression

Alzheimer's Disease vs Dementia: What's the Difference?

Alzheimer's is a disease that causes dementia. In contrast, dementia is the all-encompassing term for a general decline in mental abilities; a decline dramatic enough to impact the sufferer's quality of life.

Dementia results from Alzheimer's, other similar conditions, and injuries that directly or indirectly affect the brain. This leads to a steady decline in cognitive function.

Let's have a look at what causes Alzheimer's specifically.

What Causes Alzheimer's Disease?

The human brain comprises billions of neurons (nerve cells) that process and share information and send messages via electrical and chemical signals. Alzheimer's disease obstructs this messaging system at the neuronal level, resulting in a loss of cell function and cell death.

It is believed that Alzheimer's disease may be caused by an abnormal buildup of proteins in and around brain cells, causing a decrease in neurotransmitters involved in sending signals between neurons.

It's not entirely known why this process occurs, or what causes it. Scientists do know, however, that it begins long before symptoms appear. Over time, affected areas of the brain begin to shrink. The first area usually affected is the one responsible for memory.

So, does cannabis present any potential to impact the symptoms of Alzheimer's disease? What is it about the plant and its constituents that makes it a valid subject of scientific inquiry in this domain?

How Does Cannabis Affect the Brain?

The potential link between cannabis and Alzheimer's chiefly boils down to the herb’s effect on the brain. To start, constituents from cannabis interact with the body’s endocannabinoid system. This web of cell receptors exists throughout the body, and utilises endogenous cannabinoids—naturally-occurring cannabinoids—to mediate a wide variety of bodily functions.

There are two main types of cannabinoid receptors: CB1 and CB2. CB1 receptors are predominantly found on brain and spinal cord nerve cells, while CB2 receptors are primarily found in the immune system.

Studies suggest that when you smoke, vape, or ingest cannabis, cannabinoids like THC bind to these receptors, altering the release of neurochemicals in the brain and changing how brain cells share information. And this is where we can start to consider the potential impact of cannabis on Alzheimer’s disease.

Cannabis and Alzheimer's Disease

There is still much to learn about the long-term effects of cannabis on the brain. However, a few clinical trials have sought to determine the impact of cannabinoids on behavioural symptoms in people with dementia, most notably agitation and aggression. Interestingly, one of the most high-quality pieces of research^[1] on the subject posits that administering THC and CBD together may be more “useful” than employing either cannabinoid in isolation.

In a report published by the Alzheimer's Drug Discovery Foundation^[2], a synthetic version of THC known as Nabilone is considered for its possible effects on Alzheimer’s behavioural symptoms. The report references various relevant studies, and specifically seeks to identify if Nabilone, relative to placebo, can reduce agitation associated with Alzheimer's. Though the data is promising, especially compared to most medical research on cannabis, more extensive studies are needed before we can say with confidence whether cannabis has clinical potential in treating behavioural symptoms associated with Alzheimer's.

Is THC Good or Bad for Alzheimer’s?

Given THC’s psychotropic nature, there remains the question of whether long-term use could adversely affect the ageing brain. At present, there is not enough research to say that THC is “good” or “bad” for the brain, and it appears to be a much more nuanced conversation. Indeed, dosing and frequency play a significant role, as do age and predisposition to mental health issues.

Intriguingly, there is also talk of a potential positive effect of THC on the ageing brain. Take this 2017 study^[3], which administered chronic low doses of THC to ageing mice in hopes of reducing age-related mental decline. Though preliminary, this study, among others, clears a path for more comprehensive research on THC’s effect, positive or negative, on neurodegeneration in human subjects.

CBD and Alzheimer's Disease

There is significantly less research on the relationship between CBD and Alzheimer's. However, some early analysis^[4] has looked to determine if CBD exhibits neuroprotective properties.

Neuroprotective substances essentially protect neurons from degrading, and may offer some support against the onset and advancement of conditions such as Alzheimer's. What role, if any, CBD has to play in terms of neuroprotection is as yet unknown, but it's certainly worth investigating further.

Combining CBD and THC for Alzheimer's

As mentioned above, a 2019 study on cannabis and Alzheimer's suggests that using CBD and THC together could have a more significant impact than using eith er alone. This statement supports a theory known as the entourage effect, which claims that cannabis constituents tend to synergise when administered in tandem.

This study is not the only one indicating a beneficial relationship between THC and CBD. Indeed, the drug Sativex, which is approved to treat MS-related spasticity in the UK, features a 1:1 composition of both cannabinoids.

How to Take Cannabis for Alzheimer’s Disease

Given that cannabis is not an approved treatment for Alzheimer’s or related symptoms, we can offer no advice on using the herb for this purpose. However, in research settings, cannabis is usually administered to the test subjects in the form of an inhalable vapor or oromucosal spray, or in the form of orally or sublingually administered oils or capsules.

These methods are safer than smoking and offer greater control over dosing. In many cases, the cannabis used in clinical settings is not actually cannabis, but rather synthetic cannabinoids that mimic the ones found in the plant.

Anyone interested in utilising cannabis for holistic purposes should always consult a doctor first, as they can best assess whether it is suitable. This involves taking into account lifestyle factors, other medication, and access.

The Future of Cannabis and Alzheimer's Disease

Alzheimer's treatments are only effective in the early stages of the disease. And as the disease is still not fully understood, investigating new forms of treatment is essential.

The holistic potential of cannabis has been examined for thousands of years. Only recently has science started to explore the potential of cannabinoids for individuals living with Alzheimer's.

Traditionally, cannabis use has been linked with learning and memory problems in vulnerable people. Recent discoveries in Alzheimer's studies on animal subjects, however, point in the other direction. This is in addition to human studies administering natural and synthetic cannabinoids to small populations of Alzheimer’s patients.

Thankfully, studies are continuing apace. Many human trials are in the process of gaining funding or are underway as we speak. Hopefully, this will soon give us a definitive answer as to whether cannabis is a viable option for Alzheimer's patients.