Can marijuana help fight Alzheimer’s Disease?

alzheimer's disease
Illustration of losing brain function. SOURCE: Fotolia.

There are few conditions as terrifying as Alzheimer’s disease. When you have seen a loved one go through the slow, slipping away of their memories, their identity, and the recognition of the people they loved, the full impact of Alzheimer’s is hard to ignore. Still a cure continues to elude us. As the sixth leading cause of death in the US, affecting nearly half of those over the age of 85, the fight against Alzheimer’s is something that touches almost everyone, whether directly or through a loved one. While Alzheimer’s currently has no cure, research suggests cannabis and cannabinoids might aid in its treatment and prevention.

In a recently published study in Nature Medicine, researchers looked at the cognitive effects of THC in older mice and found that a low-dose regimen of THC reversed age-related cognitive decline. The research consisted of multiple cognitive tests – how well mice remembered their way out of a maze or to an object, as well as how well they recognized other mice. Older mice (aged 12 months) in the control groups performed worse than younger mice (aged two months) on all measures. However, in a surprising twist, when older mice were given THC, they were able to match the performance of young mice in the control group. While THC intake slowed the performance of younger mice, it brought older mice back to the cognitive abilities of their youth, greatly aiding their performance in the cognitive tests.

there are several mechanisms by which cannabinoids can help delay Alzheimer’s onset

Researchers also reported that the THC treatment actually altered the hippocampal gene transcription patterns of older THC-treated mice so that they closely resembled those of young THC-free mice. While researchers caution that these results may not carry over to human studies, they provide a strong motivation to start clinical studies on humans. If we were to see these results in humans, it could mean an extra five to ten years of living with full cognitive function.

This isn’t the first time researchers have considered cannabis as a potential alzheimer’s treatment. Other animal studies have shown promising results, and researchers believe there are several mechanisms by which cannabinoids can help delay the onset of Alzheimer’s.

The endocannabinoid system was only discovered in the 1990’s, but scientists are quickly learning that it is crucial to bio-regulation and cell signaling. This system’s activity declines with age, and some researchers believe this may be a cause of the cognitive changes we see with aging. Introducing cannabinoids activates the endocannabinoid system, and thus may be particularly well-suited to help older animals and humans keep their minds sharp.

While the underlying causes of Alzheimer’s disease aren’t fully understood, researchers have also reported cannabis can help reverse certain correlates of the disease, such as high amyloid-beta levels, plaque build-up, excitotoxicity, mitochondrial dysfunction, and neuroinflammation.

The research supporting cannabis’ efficacy against cognitive decline in animal models is strong, but legal restrictions on cannabis has make it difficult to perform similar studies on humans. Still some, like Gary Wenk (a long-time Alzheimer’s and cannabis researcher), point to trends amongst cannabis users avoiding Alzheimer’s. Wenk found that many of his older patients without Alzheimer’s had reported using cannabis in middle age. Still, Wenk’s research, like much cannabis research in the US, has stalled due to legal restrictions.

Researchers have hope that cannabis could greatly aid in the fight against Alzheimer’s, but human clinical trials are the next step to understanding its role. Still, as long as cannabis remains a schedule 1 controlled substance, it is nearly impossible to get a human study approved. Unfortunately for researchers, Alzheimer’s patients and their loved ones – this potentially life-saving research may have to wait.

[Emily Earlenbaugh is a cannabis patient consultant and wellness researcher. She is the author of the online course ‘The Mindful Guide to Cannabis’ and has a doctorate in philosophy of science from UC Davis.]