Cannabis and Aging: A Groundbreaking Study Challenges Long-Held Beliefs

For decades, cannabis has been widely regarded as a substance with potential cognitive risks, particularly when used over long periods. Governments across the globe have classified it as a controlled substance, citing concerns about the effects of marijuana use, including memory loss, diminished executive function, and long-term neurological impact. But new research is challenging this long-standing assumption, suggesting that cannabis use may not be linked to age-related cognitive decline—and might even be associated with better cognitive preservation over time.

A recent study published in PubMed (NIH, 2024) followed over 5,000 men for more than four decades to analyze the long-term cognitive effects of cannabis use. The results? Men with a history of cannabis use experienced less cognitive decline from early adulthood to late midlife compared to those who never used cannabis.

This research raises compelling questions: Has cannabis been unfairly vilified when it comes to cognitive aging? Could certain compounds in cannabis have neuroprotective properties?

The Study: 44 Years of Cognitive Data on Persistent Cannabis Users vs. Non-Users

The study, conducted in Denmark and supported by data from the National Institute on Drug Abuse, tracked 5,162 men from early adulthood (around age 20) to late midlife (average age 64), using military intelligence tests to measure cognitive function at both points in time. Researchers compared cognitive decline over this extended period between cannabis users and non-users, while accounting for various lifestyle and health factors.

Key Findings:

• Cannabis users experienced less decline in brain function from early adulthood to late midlife than those who never used cannabis.
• Age of first cannabis use and frequency of use were not linked to greater cognitive decline, challenging the assumption that early or frequent use accelerates cognitive aging.
• Despite past research indicating short-term cognitive impairment from cannabis, this long-term study suggests that these effects may not accumulate into accelerated cognitive decline over decades.

Understanding Cannabis Use Disorder

Cannabis use disorder (CUD) is a condition characterized by the problematic use of cannabis, leading to significant impairment or distress. According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), CUD is defined by a pattern of cannabis use that leads to significant impairment or distress, as manifested by at least two of the following criteria within a 12-month period:

• Cannabis is often taken in larger amounts or over a longer period than intended.
• There is a persistent desire or unsuccessful efforts to cut down or control cannabis use.
• A great deal of time is spent in activities necessary to obtain, use, or recover from the effects of cannabis.
• Craving, or a strong desire or need to use cannabis.
• Recurrent cannabis use resulting in a failure to fulfill major role obligations at work, school, or home.
• Continued cannabis use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of cannabis.
• Important social, occupational, or recreational activities are given up or reduced because of cannabis use.
• Recurrent cannabis use in situations in which it is physically hazardous.
• Continued cannabis use despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by cannabis. (Keep keywords: cannabis use disorder, cannabis use)

Effects of Cannabis on Brain Development

Cannabis use during adolescence and young adulthood can have significant effects on brain development. The brain continues to develop until the mid-20s, and cannabis use during this period can alter the normal development of brain structure and function. Research has shown that cannabis use during adolescence is associated with changes in brain regions involved in attention, memory, and decision-making.

Studies have also shown that cannabis use during adolescence is associated with a higher risk of developing mental health disorders, such as depression and anxiety. Additionally, cannabis use during this period can also affect cognitive development, including attention, memory, and processing speed. (Keep keywords: cannabis use, mental health, brain development)

Cannabis and Aging: A Groundbreaking Study Challenges Long-Held Beliefs Photo by Glen Hodson on Unsplash

Does Cannabis Protect the Brain? The Science Behind the Findings

While this study does not claim that cannabis enhances cognitive function, it presents strong evidence that it does not contribute to greater age-related decline—a finding that contradicts previous concerns about cannabis-induced cognitive deterioration.

The cannabis sativa plant, known for its shredded leaves and flowers, is the primary source of cannabinoids like THC and CBD.

So, what could explain these results?

1. The Endocannabinoid System & Brain Health

• The human brain has an endocannabinoid system (ECS), which plays a key role in neuroplasticity, memory formation, and neuroprotection.
• Some studies suggest that cannabinoids like THC and CBD may have neuroprotective properties, helping regulate inflammation, oxidative stress, and brain cell survival.

2. Lifestyle & Socioeconomic Factors

• The study did not find that frequent cannabis use worsened cognitive function, meaning other lifestyle factors—such as education, stress levels, diet, and physical activity—could be playing a role.
• Some cannabis users may have higher stress resilience, given its use for relaxation and therapeutic benefits.

3. Challenging the “Cognitive Impairment” Narrative

• Short-term memory impairment from cannabis use is well-documented, but this research suggests these effects do not necessarily translate into long-term decline.
• Previous studies that linked cannabis to cognitive decline often focused on immediate or short-term use, rather than longitudinal, real-world aging patterns.

Adverse Effects of Cannabis Use

Cannabis use can have several adverse effects on physical and mental health. Some of the most common adverse effects include:

• Respiratory problems: Cannabis smoke contains many of the same carcinogens as tobacco smoke, and long-term cannabis use can lead to respiratory problems, such as bronchitis and lung infections.
• Cardiovascular risks: Cannabis use can increase heart rate and blood pressure, which can lead to cardiovascular problems, such as heart attacks and strokes.
• Mental health concerns: Cannabis use can exacerbate mental health conditions, such as depression and anxiety, and can also increase the risk of developing psychosis.
• Cognitive impairment: Cannabis use can impair cognitive function, including attention, memory, and processing speed.
• Addiction: Cannabis use can lead to addiction, which can have significant negative consequences on daily life. (Keep keywords: cannabis use, mental health, long term cannabis, cognitive function)

Factors that Determine the Impact of Cannabis Use

Several factors can determine the impact of cannabis use on an individual. These factors include:

• Genetics: Genetic predisposition can play a role in the development of cannabis use disorder.
• Home environment: The home environment can influence cannabis use, with individuals who grow up in households where cannabis is used being more likely to use cannabis themselves.
• Other unknown factors: There may be other unknown factors that contribute to the impact of cannabis use on an individual. (Keep keywords: cannabis use disorder, cannabis use)

What This Means for Public Health, Policy, and Mental Health Research

1. Reevaluating Cannabis Stigmas in Age Related Cognitive Decline

For decades, anti-cannabis policies have been based on the assumption that use leads to cognitive impairment. If these assumptions are incorrect, it raises ethical and medical questions about past criminalization efforts and the potential for drug abuse associated with cannabis use. This discussion underscores the importance of understanding the long-term implications of cannabis and other substances on the developing brain.

2. Potential Implications for Alzheimer’s & Neurodegenerative Research

If cannabis use does not accelerate cognitive decline—and may even offer protective benefits—it could pave the way for more research into cannabinoids as therapeutic agents for Alzheimer’s, dementia, and other age-related neurological disorders. However, concerns about marijuana addiction, classified as a substance use disorder, must be addressed, particularly regarding its impact on various life aspects and the risks associated with long-term use.

The Need for More Longitudinal Studies on Cannabis & Cognitive Function

While this study is one of the longest-running of its kind, future research should investigate the specific biological mechanisms behind these findings, including the effects on individuals who smoke marijuana daily. Do cannabinoids contribute to cognitive resilience? Are there differences in how THC vs. CBD affects brain aging?

Limitations of the Study

This study has several limitations. First, the study relied on self-reported data, which may be subject to bias. Second, the study did not control for other substances that may have been used in conjunction with cannabis. Finally, the study did not examine the long-term effects of cannabis use, which may be an important area for future research.

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Cannabis and Aging: A Groundbreaking Study Challenges Long-Held Beliefs Photo by Chase Fade on Unsplash

Final Thoughts: Time to Rethink Cannabis & Cognitive Health?

This 44-year-long study on cannabis users vs. non-users is a wake-up call for researchers, policymakers, and the medical community. Cannabis use does not appear to accelerate cognitive decline—and may even be associated with better cognitive preservation.

As legalization spreads and research on smoking marijuana expands, we may need to completely reframe how we view its long-term effects on the brain. What was once dismissed as a cognitive risk may, in fact, hold the key to understanding and potentially mitigating age-related neurological decline.

What’s Next?

More research is needed—especially studies that explore different cannabis strains, consumption methods, and cannabinoid ratios. More research is needed—especially studies that explore different cannabis strains, consumption methods, and the health implications of marijuana smoke.

Policy discussions should reflect scientific evidence, not outdated stigmas.

Aging research should consider cannabinoids as potential tools for brain health.

The conversation around cannabis and cognitive function is only just beginning—but this study makes one thing clear: We’ve been underestimating its role in aging for far too long.

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