The Connection Between Cannabis & Cognitive Mental Health:

Can Cannabis Therapy Help Protect Against Cognitive Decline?   Pros and Cons…

As cannabis gains popularity for its therapeutic benefits and recreational use, its impact on cognitive health is a growing topic of research. Much of this research is particularly focused on certain populations, especially populations in the older age groups. A recent study conducted through SUNY Upstate Medical University in Syracuse, New York sheds interesting light on a possible interactive relationship between cannabis use and cognitive function in adults over 45. Essentially, this brief article will explore whether cannabis use (especially as it regards age and level of usage) may negatively or positively affect your long-term cognitive ability to think and function.

Pros: Exploring Cognitive Health and Cannabis

On April 9, 2024, Neuroscience News published “Cannabis Use Linked to Lower Dementia Risk,” a study by Professor Roger Wong (Ph.D., MPH, MSW) and Zhi Chen (MPH); read: (https://neurosciencenews.com/cannabis-dementia-neurology-25884/). Based on data from the CDC’s 2021 Behavioral Risk Factor Surveillance System (BRFSS), this research revealed a seemingly positive relationship between recreational cannabis use and daily cognition. The study was first published in the multidisciplinary, peer-reviewed medical journal Current Alzheimer Research.

This study is remarkably unique because it was geared to specifically target older adults. 4,744 Adults from the ages of 45 and older who were part of the 2021 (BRFSS) were evaluated for potential Subjective Cognitive Decline (SCD). SCD refers to patient self-reported issues regarding memory, thinking abilities, confusion or memory loss, which may interfere with common daily activities.

SCD can often be an early indicator of cognitive disorders, such as dementia.

Interestingly, findings revealed that adults who reported some degree of recreational cannabis use had a 96% lower instance of experiencing SCD. This suggests that cannabis may protectively inhibit negative effects upon cognition in midlife and older adults.  

As more longitudinal research to understand the long-term impacts are being called for, these findings are opening the door for a more thorough understanding of the effects of recreational cannabis use on lifelong cognition in older adults. Lately, much of the public and academic conversation surrounding cannabis use is beginning to focus on a distinction between the effects of recreational and medicinal use. For instance, medical-grade cannabis is going to be higher in CBD, than THC. Conversely, recreational-grade cannabis is higher in THC, than CBD.

Pros: Does Frequency or Method Matter?

According to Wong, all of the dimensions of cannabis use were examined in this study (smoking, vaping, eating and/or dabbing). Surprisingly, the study found no significant link between the frequency and/or method of cannabis use, and cognitive decline. Whether the participants who used cannabis were occasional or habitual consumers, the results remained consistent.

Likewise, whether participants consumed cannabis via inhalation, edibles or ingestion through other means, again the results remained consistent. There was no significant link between the various methods and cognitive decline. Therefore, both frequency and method of cannabis consumption were not found to be significantly associated with SCD.

Being afflicted with SCD puts an individual at a 2x higher risk for eventual dementia later in life than non-afflicted SCD individuals.

The strengths of the study are reflected in the fact that a national data group was used which gives a broad canvas of information from across the country. The study also pointed out that there are differences in the grades of cannabis which alter the outcomes of those studied in the data group.  

 Pros: Why Might Cannabis Protect Cognition?

Although the exact mechanisms are unclear, researchers speculate that cannabis’s interaction with the body’s endocannabinoid system may play a role in cognitive health.

The endocannabinoid system regulates various functions, including mood, memory and inflammation. Cannabinoids such as THC and CBD are active compounds in cannabis and may reduce neuroinflammation and oxidative stress. These are two factors which are often linked to cognitive decline and neurodegenerative diseases.

According to the National Institute of Health (NIH), “Recent studies have shown that THC can promote neurogenesis, restore memory and prevent neurodegenerative processes and cognitive decline in animal models of Alzheimer’s Disease.” “Cannabis Effects on Brain Structure, Function and Cognition: Considerations for Medical Uses of Cannabis and Its Derivatives” by Burggren, Shirazi, Ginder & London; February 18, 2020. This study has led to a focus on “considerations for age limits and guidelines for use.” For more detailed information on cannabis and neurogenesis, read: (https://pmc.ncbi.nlm.nih.gov/articles/PMC7027431/?fbclid=IwAR1KosfIgEXolh9jW-q6bI7GPLlKt8weTSqfaXkatZ6skAgjuY5tU0oJV4I).

Cons: Cautions and Limitations

The results of Wong and Chen’s study are a “snapshot of a year,” which is a notable departure from earlier research on younger populations. In these earlier studies, cannabis use was often associated with negative effects on cognitive function in younger adults. Essentially, the recent results suggest a potentially different interaction between cannabis and the biochemistry of the younger vs. older human brain.

Research recently published addresses the issue of age, as it relates to cannabis therapy. In The American Journal of Psychiatry, the study, “Long-Term Cannabis Use & Cognitive Reserves and Hippocampal Volume in Midlife”, Vol. 179, #5, 3/8/2022: (https://psychiatryonline.org/doi/full/10.1176/appi.ajp.2021.21060664) examined over 1,000 individuals (ages 3-45 but primarily ages 18-45) for cannabis-related cognitive decline, in the country of New Zealand. Results showed that people who engaged in heavy use earlier in life (at least weekly to 4x’s a week) showed impaired cognitive function across many areas. Furthermore, the impairment was more severe than heavy alcohol or tobacco use. These long-term users showed smaller hippocampi (the region of the brain that is responsible for learning and memory).

However, those who used less than once a week did not show cannabis-related cognitive deficits. According to Kevin Hill (MD, MHS) & Michael Hsu (MD) of Harvard who reviewed the study, this suggests that “there is a range of recreational use that may not lead to long-term cognitive issues,” which also factors in age. For Hill and Hsu’s complete review of the New Zealand study in The American Journal of Psychiatry, read: (https://www.health.harvard.edu/blog/cognitive-effects-of-long-term-cannabis-use-in-midlife-202206142760). So it seems that the earlier an individual’s heavy use begins, the more likely you may experience issues related to cognitive decline. This implies that light use may be a useful and safer therapeutic range for cannabis therapy, than chronic, heavy over-use.

Neuroscientist Staci Gruber, EdM ‘95, Ph.D. is a Harvard Medical School Associate Professor of Psychiatry. She directs both the Cognitive and Clinical Neuroimaging Core (CCNC) and the Marijuana Investigations for Neuroscientific Discovery (MIND) program at McLean Hospital, the flagship mental health hospital of Harvard Medical School.  

According to Gruber, heavy recreational cannabis use before age 16 will impede the physical development of the brain and, therefore, cause cognitive decline, as opposed to people who began heavy recreational use later in life. Prior to adulthood, while the brain is still developing, adolescents will perform poorly when it comes to cognitive tasks involving the frontal cortex, which addresses memory, attention and judgment.

Gruber also states that neuroimaging of the brains of early-onset cannabis users (16 and younger) has revealed changes in white matter, the neural fibers which are critical for efficient communication among the regions of the brain. For more information on this subject, read D. Bradley Ruder’s “Cannabis and the Brain”, Spring 2020, published in Harvard Medical School’s Publication Archive: (https://hms.harvard.edu/news-events/publications-archive/brain/cannabis-brain).

Consequently, while the findings of Wong and Chen’s study are promising, researchers caution against drawing broad conclusions. The study was observational, meaning it captures a snapshot of behavior and outcomes at a single point in time. It cannot establish a specific causation: whether or not cannabis itself directly reduces the risk of cognitive decline or if other factors may play a role in this reduction.

Moreover, Wong and Chen’s study relies on self-reported data, which can sometimes lack precision or be influenced by biases. Wong (an assistant professor for the Department of Public Health & Preventive Medicine at SUNY Upstate Medical University) emphasizes the need for future longitudinal studies, which follow participants over a longer time period. This longer period would allow researchers to better understand cannabis’s long-term effects on younger vs. older cognitive health.

Furthermore, Wong asserts that we do not know yet if recreational cannabis use leads to better cognition or if individuals who already have better cognition are just more likely to use recreational cannabis. This is the distinction that needs to be studied. However, this is currently very difficult to do since cannabis is still federally illegal, which greatly hinders any attempts at studying cannabis in the United States. Furthermore, state-by-state differences in cannabis legislation also hinder current research.  

On a side note, Wong also points out that his and Chen’s study revealed some possible limits regarding CBD. He states that they “don’t see the CBD in medical cannabis being beneficial for cognitive health.”

The Bigger Picture: Cultivating A Balanced Perspective

The various studies and research in the specific area of cognitive development and wellness have discovered some intriguing results in cannabis therapy. Among these results are developmental, structural and functional differences in the human brain which are linked to light vs. heavy cannabis use. Some of these results have spawned some early theories and conclusions.

It’s essential to approach these findings with a sense of balance. While cannabis studies have shown promise as a potential aid for cognitive health, it’s not without risks. Overuse or improper use can lead to side effects. In addition, the analysis of long-term side effects on both young and aging brains remains under-researched, given the current restrictions governing cannabis legislation in the United States. Moreover, cannabis’s benefits may or may not vary based on the individual’s age, diet, level of physical activity, general state of health (both mental and physical), physical state of their environment, personal genetics and/or their method of consumption. In the studies mentioned in this article, age seems to be a critical factor.

On a positive note, this study opens the door for further exploration and investigation into how cannabis therapy may support brain health as we age. It challenges long-standing assumptions about cannabis and cognition, while emphasizing the importance for nuanced, empirical, evidentiary-supported research in forming new theories and opinions. For now, these findings offer a glimmer of hope for those seeking a so-called “natural,” non-pharmaceutical approach to maintaining overall brain health.

However, as far as risks go the relationship between cannabis and cognitive health is growing into an ever-growing, critical area of study but again it’s still in the early stages of development. New studies revealing interactive characteristics concerning cannabis are emerging piecemeal. As cannabis legalization expands and as more adults incorporate it into their wellness routines, pursuing a professionally unadvised course could lead to negative complications down the road. The path to objectively understanding the nuances of cannabis therapy and how issues such as age affects its interaction with the human body is vital when incorporating it into your life. This is especially true if you’re considering cannabis therapy for children and/or adolescents. Consequently, for those considering cannabis therapy, especially for cognitive health or other health-related purposes, consulting a healthcare professional is wisely advised. Personalized advice based on your individual medical history can help you better navigate the potential benefits and risks of cannabis therapy.

Hence, as cannabis legislation evolves and new research is pursued, there is the promise of more intriguing insights to come addressing the pros and cons of cannabis use. In the meantime, again, it remains important to always include your cannabis use in your discussions with your personal physician or health care professional. This will ensure that your knowledge, awareness and practice of cannabis therapy is always as up-to-date as possible.

Cannabis’s role in cognitive health may still be in its early stages of understanding but studies like this are paving the way for enlightening possibilities. Whether for recreation or wellness, cannabis therapy continues to challenge perceptions and redefine its role in human health in the 21st century.

Key Points to Remember:

• Wong and Chen’s study states that recreational cannabis use was linked to a 96% reduction in the risk of SCD (in adults over 45).
• SCD can be an early indicator of cognitive disorders, such as dementia. Furthermore, being afflicted with SCD puts an individual at 2x the risk for dementia, later in life.
• Wong and Chen’s study showed no significant differences were found based on frequency or method of cannabis use, as it applies to the risk of SCD.
• More longitudinal studies are needed to confirm long-term effects and establish exact causation, as cannabis therapy applies to SCD.
• Studies under Harvard Medical School and published in psychiatric medical journals found that heavy use showed negative symptoms in brain development and (especially among those aged 16 and under) changes in brain matter, as well as a smaller hippocampus.
• There is a range of recreational use that may not lead to long-term cognitive deficits, depending upon many factors. For example, the age when recreational and/or heavy, chronic cannabis use began can affect the risk of SCD.
• Professor Wong states that CBD in medical cannabis showed no significant benefits in managing cognitive health.
• The National Institute of Health states that THC may promote neurogenesis, restore memory and prevent neurodegenerative processes and cognitive decline in animal models of Alzheimer’s Disease.
• Keep yourself informed and updated about medical studies regarding current breakthroughs in cannabis therapy through your personal physician.
• Always consult a medical professional before including any kind of cannabis therapy into your health routine.

Further Reading

1. “Subjective Cognitive Decline (SCD)” refers to self-reported memory or thinking problems that may indicate early cognitive impairment. For more information, visit the CDC’s page on SCD.
2. Wong and Chen’s research on SCD is based on data from the CDC’s Behavioral Risk Factor Surveillance System (BRFSS), a national survey collecting health-related data.
3. Further reading/research on cannabis therapy and cognitive health can be found in medical journals and publications, such as Neuroscience News, The American Journal of Psychiatry, The National Institute of Health (NIH) and Harvard Medical School: Harvard Health Publishing, Publication Archives.

Author: TMcCain