April 22, 2026, 12:18 pm | Read time: 7 minutes
A comprehensive long-term study with over 11,000 participants dispels the stereotype that primarily underperforming children and adolescents turn to cannabis. Those who later used cannabis were often mentally sharper as children and performed better in concentration and memory than their peers. However, this initial advantage becomes a trap: While the brain undergoes a significant cognitive boost during puberty in others, cannabis acts as a “developmental brake.”
Teen Cannabis Users Apparently Miss Out on Brain’s Turbo Development
A research team led by Natasha Wade followed 11,036 children over about seven years—from childhood at ages nine or ten to the end of puberty (17 years). The key findings: Cannabis acts as a “developmental brake.”1 While the brains of non-users experience a significant cognitive boost during puberty, this developmental curve flattens or stagnates in users.
Stereotype of the Underperforming Cannabis User: Future Cannabis Users Often Mentally “Fitter” as Children
At the same time, those who later use cannabis often performed better in areas such as working memory or concentration compared to their peers as children. Researchers suspect that adolescent cannabis users might be slightly more advanced in their development or more inclined to seek new experiences early on. Such traits could also increase the likelihood of later cannabis use.
Research Methodology
For the study, researchers used data from the large ABCD study in the U.S. By including children as young as nine and ten, researchers could track changes from the first use of cannabis over time.
Mental performance was repeatedly tested with small “brain checks.” Children and adolescents had to memorize and later recall word lists to test memory. Other tasks involved quick reactions and avoiding distractions, showing how well concentration and self-control functioned.
Thinking speed was also measured, with participants needing to solve tasks as quickly as possible. Additionally, language comprehension and spatial thinking were tested, assessing abilities to organize or visualize things mentally.
Cannabis Use Verified Through Hair Analysis
Later, researchers used hair analyses to determine if someone had regularly used cannabis over weeks or months. This made the data significantly more accurate than in many previous studies.2,3,4 Researchers also considered other influencing factors, such as alcohol and nicotine use, family background, or psychological issues.
Also of interest: Study with over 40-year-olds—how cannabis use affects the brain
Key Cognitive Abilities Decline Due to Cannabis Use
The results show: While adolescent non-users experience rapid mental growth during puberty, key cognitive abilities decline in cannabis users. A growing gap emerges. By the age of about 15 to 17, the difference is clearly measurable.
Impact on Memory
This is particularly evident in memory. In tests, users remembered fewer words and had more difficulty recalling them later. This affects both short-term memory and long-term retention of information.
Concentration and Self-Control Affected
Concentration and self-control are also affected. In tasks requiring the ignoring of distractions, users made more errors or reacted more slowly. This suggests it is harder to focus and control impulsive behavior.
Another area is processing speed, or how quickly the brain works. Here, tasks were solved more slowly. In everyday life, this can mean taking longer to process information or make decisions.
Differences in Language Skills and Spatial Thinking
Language skills and spatial thinking also developed more weakly. The latter is important for visualizing routes or understanding technical relationships. The differences were clear and demonstrable in tests.
THC Behind the “Developmental Brake”
A particularly revealing additional analysis: The study provides concrete evidence that THC is the actual mechanism behind the “developmental brake” on memory. While cannabis contains hundreds of compounds, this analysis shows that specifically the intoxicating component (THC) gradually “clamps down” on episodic memory.
This is intriguing because it refutes or at least nuances a common prejudice: Cannabis is often viewed as a uniform substance that “damages” the brain across the board. The study nuances this by identifying the specific “culprit”: While THC (the intoxicating component) is clearly linked to slowed memory development, this negative effect could not be demonstrated for CBD (the non-intoxicating component) in this study.
CBD products are by no means harmless: Researchers explicitly warn that many commercial CBD products may be contaminated with THC. So those who think they are consuming CBD products risk-free might inadvertently still “slow down” their brain with THC.
The Difference Between THC and CBD
THC and CBD are the two main compounds in cannabis, but they work completely differently.
THC (Tetrahydrocannabinol) is the substance responsible for the typical “high.” It acts directly in the brain, altering perception and mood and can also affect thinking and memory. This effect is suspected of slowing cognitive development.5
CBD (Cannabidiol) does not have an intoxicating effect. It has a calming and relaxing effect and is sometimes even associated with positive effects on inflammation or stress.6 Another difference: CBD products are legal in Germany as long as they contain only very small amounts of THC. THC itself is considered an intoxicating substance and is legally restricted.
Also of interest: CBD Oil—Effects, Study Situation, and Expert Assessment
Implications for Everyday Life
The results show primarily one thing: The changes happen gradually. Adolescents often do not immediately notice that their performance is developing differently. They do not suddenly become “worse,” but simply improve more slowly than others. Over the years, this creates a real gap.
This can become noticeable in everyday life. In school, it becomes harder to remember material or work with concentration. Tasks take longer, exams become more strenuous. These skills also play an important role outside of school. Quick thinking, good memory, and concentration are crucial in traffic, sports, or later in a career.
The initial advantage is also interesting: Researchers suspect that adolescents who are slightly more developed or risk-taking are more likely to use cannabis. However, this lead is lost over time.
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Limitations and Conclusion
Major Strength: Extensive and Long-Term Data
The study provides very reliable results—mainly because it followed a large group of over 11,000 children over many years. A particular advantage is also the combination of surveys and biological tests. This allowed researchers to capture cannabis use much more accurately than in many previous studies.
Not All Use Is Detected
However, there are some limitations to consider. Certain tests, such as hair analyses, primarily detect regular use. Those who have only tried it occasionally or once might remain partially undetected.
Uncertainties with Individual Cannabis Compounds
The analysis of individual components is also still cautiously evaluated: In the subgroup with hair analyses, there were a total of 645 adolescents—but only 21 had detectable CBD, while 81 had THC in their hair.
The CBD group was therefore very small. Thus, the results for this compound can only be evaluated to a limited extent.
No Clear Cause-Proof
Another important point: The study shows clear correlations, but it cannot definitively prove that cannabis alone is the cause of the altered development. Other factors—such as personality, environment, or lifestyle—could also play a role.
Conclusion: Early Cannabis Use Can Slow Development
Despite these limitations, a clear overall picture emerges: Those who start using cannabis early develop certain cognitive abilities more slowly on average. The compound THC is particularly suspected of negatively affecting memory.
Especially because the brain is particularly sensitive and develops significantly during youth, such differences can intensify over the years. What initially goes unnoticed can have noticeable long-term consequences—in school, everyday life, or later in a career.