What Are CBD’s Effects on the Brain?

While it’s clear that cannabidiol (CBD) has various effects on the brain that are mostly positive…

Not all effects are currently known.

For example:

CBD’s effects on the developing infant and teenage brain are not well-researched.

The most well-researched effects of CBD on the brain are positive ranging from:

• Neuroprotective effects, to;
• Anxiety-reducing effects.

Today you’re going to learn all the known effects of CBD on the brain.

But also:

What areas of CBD- and brain-related research are underdeveloped and thus in which instances caution is advised with the use of CBD.

Let’s get started.

Table of contents:

Does CBD Affect Memory?

Does CBD Affect Cognitive Function?

Does CBD Cause Brain Damage?

Can CBD Reverse Brain Damage?

How Does CBD Affect the Infant and Teenage Brain?

What Else Does CBD Do the Brain?

What’s the Relationship Between CBD and Brain Fog?

Does CBD Affect Memory?

Different studies have looked at the effects of CBD on memory.

While study results are mixed, the general consensus is that CBD has the potential to improve:

• THC-induced memory-impairment, and;
• Neurodegenerative-disease related memory impairment, like Alzheimer’s disease.

In other words, CBD seems to have a positive effect on memory, at least within the context of memory impairment of different sorts.

The effects of CBD on memory under ’regular’ or ‘healthy’ circumstances don’t seem to be significant.

Let’s dive a bit deeper into the most important CBD- and memory-related studies.

Study 1: Impact of CBD on Memory Impairment Caused by Smoked Cannabis

As explained, while THC can impair memory, CBD has been shown to reverse this memory impairment.

For example:

A study (1) done in 2011 found differences between two groups:

• One group smoked a cannabis strain with a high THC, but low CBD content;
• The other group smoked a cannabis strain with high THC, and high CBD content.

The researchers measured how they performed various memory assessments.

The group that smoked the low-CBD strain showed signs of memory impairment. THC is known to impair memory and cognitive function.

The group that smoked the high-CBD strain showed no signs of memory impairment. This group performed the memory assessments in the same manner under influence of cannabis as they did sober.

This study clearly indicates that CBD can counteract the memory-impairing properties of THC.

While the exact mechanism of action responsible for CBD’s protective effects from THC-induced memory impairment needs more research, the researchers hypothesize that it might be related to CBD’s behavior to bind to the cannabinoid 1 receptor (CB1) and block its activation by THC.

Keep in mind that all CBD products always contain a high amount of CBD and a low amount of THC, if any at all. Therefore, based on this study, you don’t have a reason to worry about memory impairment when taking any federally legal CBD product because they always contain less than 0.3% THC.

On the other hand, most cannabis strains contain a very high amount of THC, but a very low amount of CBD. The average cannabis strain bought from your dispensary has a big chance to cause memory impairment.

To avoid experiencing memory impairment when smoking cannabis, you could:

• Look for a high-CBD strain, or;
• Consume a good amount of CBD inside oil or gummies, for example.

Study 2: CBD Inhibits THC-Elicited Paranoid Symptoms and Memory Impairment

This is another study that looked at the effects of CBD on THC-induced memory impairment (2).

The study participants were divided into two groups. Both groups received 1.5mg of intravenous THC, however, only one group was pre-treated with 600mg of oral CBD.

The group that wasn’t pre-treated with 600mg of CBD scored significantly worse on measures of episodic memory.

Study 3: Memory Effects of CBD Relevant to Neurodegenerative Disorders

One negative side effect of neurodegenerative diseases is that they lead to cognitive impairment, including memory impairment.

An animal study done in 2011 found that a single injection of a very high dose of CBD recovered memory in rats that received large amounts of iron (3). The accumulation of iron in the brain is known to induce memory impairment.

Interesting to note is that the researchers also looked at the effects of both acute and chronic CBD on memory in the control group (that didn’t receive an iron treatment). They found that CBD didn’t affect the memory of the healthy rats in the control group.

Study 4: Long-Term CBD Treatment Prevents the Development of Memory Deficits in Alzheimer’s Disease Mice

A 2014 study looked at the effects of long-term CBD treatment on ‘social recognition memory deficits’ in mice with Alzheimer’s disease (AD) (4).

The AD mice were treated with CBD (20 mg/kg) daily for 8 months. The mice were then assessed on various measures including memory and physiological measures like oxidative damage, cholesterol, and inflammation.

They found that CBD prevented social recognition memory deficit. CBD protected the mice from not being able to recognize other mice.

They also found that CBD has a ‘subtle’, but positive impact on neuroinflammation and cholesterol.

Study 5: The Effects of CBD on Cerebral Blood Flow and its Relationship to Memory

The most recent study in the list that looked at the effects of CBD on memory…

This 2020 study looked at the effects of CBD cerebral blood flow in brain regions that are associated with memory processing (5).

The study found that CBD increases cerebral blood flow in ‘key’ regions that are associated with memory processing, especially the hippocampus.

Interestingly enough, the researchers didn’t find an improvement in the assessment of memory after the administration of CBD. The study subjects were all healthy volunteers.

This finding as well indicates that the consumption of CBD has no effect on memory in healthy people (neither positive nor negative).

Because this study shows CBD increased cerebral blood in the hippocampus, it could have implications for conditions where this blood flow is reduced, like Alzheimer’s disease.

Studies That Didn’t Find Any Positive Effects of CBD on Memory

Not every study that looked at the effects of CBD on memory found that it improved memory, even in memory-impairing situations like the consumption of THC or schizophrenia.

For example, this 2018 study that looked at the effects of CBD and THC on memory function didn’t find any positive effect of CBD on THC-induced memory impairment (6).

Another study done in 2018 that looked at the effects of CBD on cognition and symptoms in patients with schizophrenia found that CBD had no cognitive benefits (which includes memory) (7).

The Bottom Line

While study results are mixed, it seems that CBD at least has some potential to improve memory when it comes to memory-impairing situations like the consumption of THC or neurodegenerative diseases.

It seems that CBD has no influence on memory or memory processing in healthy individuals.

RELATED: Marijuana’s Effects on the Brain

Does CBD Affect Cognitive Function?

Cognitive function is a broader measurement than memory. While memory is part of measuring cognitive function, cognitive function includes other measurements like orientation, language, and visuospatial skills as well.

While the immediate effects of CBD on cognitive function are interesting, there are currently no studies that found CBD has an immediate impairing effect on cognitive function.

On the contrary, there are studies that show CBD can improve cognitive function as a short-term effect, but only within the context of THC-induced cognitive impairment.

Study 1: CBD and THC-Induced Cognitive Impairment

For example, one study that looked at the acute effects of CBD on brain function in healthy volunteers that were given THC found that CBD improved (8):

• Emotional processing;
• Verbal memory;
• Response inhibition, and;
• Auditory/visual processing.

Based on current studies, it seems that even a single dose of CBD can improve THC-induced cognitive impairment.

But there are also studies that looked at the long-term cognitive effects of CBD.

Study 2: 1-Year CBD Treatment Doesn’t Produce Negative Effects on Cognitive Function in Epilepsy Patients

For example:

One study that looked at the long-term effects of CBD on cognitive function in treatment-resistant epilepsy patients found that (9):

• CBD was cognitively and functionally well-tolerated within a one-year time frame.
• Patients scored similarly on cognitive tests at the beginning of the study and one year later.

Although CBD didn’t significantly improve cognitive function in this study, it didn’t have a negative effect either.

In fact, there was even a statistically nonsignificant trend toward improvement in some of the cognitive measures.

This study indicates that CBD has no long-term negative, or positive effects on cognitive function in epilpesy patients.

Study 3: A Review of the Effect of CBD on Cognitive Function: Relevance to Schizophrenia

A review-study that looked at the effects of CBD on cognitive function within the context of schizophrenia found that (10):

While CBD has no significant effect on cognitive function in healthy states or individuals, it does improve cognition when it comes to neuro-inflammatory and neurological disorders. This held true for both acute and chronic CBD administration.

The bottom line:

Based on current studies we have no reason to think that CBD has any long-term negative consequences for cognitive function in adults. CBD may have a cognitive-improving effect in situations where cognition is impaired through neurodegenerative disease or an external compound like THC.

Does CBD Cause Brain Damage?

There’s currently no evidence that CBD causes brain damage in adult humans.

On the contrary, dozens of studies indicate that CBD has neuroprotective effects.

While human studies are rare, animal studies are plenty.

For example:

One rat-study found that chronically administered CBD, starting several days before the injury-inducing event, has neuroprotective effects and causes a significant reduction in the death of brain tissue (11).

A different study found that CBD administered to β-amyloid (Aβ)-injected mice, has neuroprotective effects by preventing (Aβ)-induced microglial activation (12). Microglial activation is thought to play an important role in neurodegenerative diseases like Alzheimer’s disease.

The bottom line:

We have no reason to think that CBD causes any brain damage to adult humans. On the contrary, studies indicate that CBD may have neuroprotective effects.

Can CBD Reverse Brain Damage?

There are currently no studies that show CBD can reverse permanent brain damage.

However, earlier you have learned that CBD can reverse certain types of temporary brain damage related to THC intoxication or neurodegenerative diseases. Especially those types of temporary brain damage that cause cognitive decline.

Keep in mind that his reversion of temporary brain damage caused by CBD may be temporary in and of itself.

One interesting study showed that CBD can aid neurogenesis (the process by which new brain cells are created) in mice (13). This doesn’t mean that CBD can reverse permanent brain damage, but it’s definitely something that warrants further research.

How Does CBD Affect the Infant and Teenage Brain?

There are currently not enough scientific data to say with certainty whether CBD affects:

• The infant;
• Teenage, or;
• Developing brain, more generally.

Some studies suggest that even small amounts of exposure to cannabinoids can have major effects on the developing brain, but most of these studies didn’t look at the specific effects of CBD (14). Most of these studies looked at the effects of cannabis. It might be that these study results are heavily influenced by the effects of THC, which is known to impair cognitive function, even more so in a developing brain (15).

We do know that cannabinoids like CBD cross the placental barrier. For example, some studies have suggested that fetal exposure to cannabinoids can reduce the proper development of the immune system and the microbiome.

We also know that cannabinoids like CBD can cross the blood-brain barrier. But there are no studies that looked at the effects of CBD on a fetus brain.

The fetal brain of course is much less developed than a teenage or even an infant brain and therefore might be even more susceptible to influence by compounds like CBD. Because of these reasons we highly advise against using CBD during pregnancy or breastfeeding.

Based on the earlier-mentioned study that looked at the long-term effects of CBD on cognitive function in treatment-resistant epilepsy patients we can say a few things, however (16).

The study participants were all aged between 3 and 19 years. This means all these study participants can be qualified as having an infant, teenage, or developing brain.

Based on these study results we can at least see that CBD probably has no long-term effects on cognition in a developing infant or teenage brain in individuals with treatment-resistant epilepsy.

However, caution is advised because the study sample was small (38 participants) and the participants had a pre-existing condition (epilepsy).

There are currently no studies that looked at the long-term effects of CBD in a developing infant/teenage brain when it comes to healthy individuals.

What Else Does CBD Do the Brain?

CBD has various actions on receptor systems inside the brain.

For example:

CBD’s anti-anxiety and anti-depressant effects are partially thought to be produced by CBD’s interaction with serotonin receptors which are found all throughout the brain (17).

CBD’s pain-reducing effects are partially thought to be produced by CBD’s interaction with adenosine receptors (18), which are abundant in the basal ganglia (a part of the brain).

CBD’s seizure-reducing (anticonvulsant) effects are, among other mechanisms of action, thought to be related to its neuronal inhibition of GABA uptake. GABA is a neurotransmitter that’s abundant in various parts of the brain.

It’s highly probable that CBD’s biochemical effects on the brain are much more complex and multi-faceted than what is currently known, and much more research is needed to fully understand these effects.

What’s the Relationship Between CBD and Brain Fog?

Brain fog isn’t a medical term. What’s meant with brain fog is generally a lack of mental clarity or impairment of cognitive function.

If we define brain fog as a lack of mental clarity, it can have a variety of causes. As explained before ‘brain fog’ can, for example, can be the result of:

• Consuming psychoactive compounds like THC;
• Neurodegenerative diseases, or;
• Traumatic brain injury.

So, can CBD help with brain fog?

Based on current studies we can only say that:

If your brain fog is the result of THC consumption or a neurodegenerative disease, CBD may be able to improve your brain fog.

Conclusion

Based on the current scientific literature we can say that CBD has no immediate or long-term negative effects on the brain.

On the contrary, there’s sound scientific evidence suggesting that CBD could have positive effects on the brain, especially within the context of THC consumption or neurodegenerative diseases, including:

• Neuroprotective effects;
• Memory-improving effects, and more generally;
• Cognition-improving effects.

What’s more, is that CBD can have:

• Anxiety-reducing;
• Anti-depressant, and;
• Seizure-reducing effects,

Through its interaction with various receptor systems found in the brain.

Although it seems that CBD has no long-term negative effects when it comes to cognition in the developing infant or teenage brain, caution is advised because the topic of CBD’s effects on a developing brain is a largely undeveloped area of research.

What’s Next…

Go  to our CBD Hub to learn more about CBD-related topics.

Scientific References

1. Morgan, C. J. A., Schafer, G., Freeman, T. P., & Curran, H. V. (2010). Impact of cannabidiol on the acute memory and psychotomimetic effects of smoked cannabis: naturalistic study. British Journal of Psychiatry, 197(4), 285–290. https://doi.org/10.1192/bjp.bp.110.077503

2. Englund, A., Morrison, P. D., Nottage, J., Hague, D., Kane, F., Bonaccorso, S., . . . Kapur, S. (2012). Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment. Journal of Psychopharmacology, 27(1), 19–27. https://doi.org/10.1177/0269881112460109

3. Fagherazzi, E. V., Garcia, V. A., Maurmann, N., Bervanger, T., Halmenschlager, L. H., Busato, S. B., . . . Schröder, N. (2011). Memory-rescuing effects of cannabidiol in an animal model of cognitive impairment relevant to neurodegenerative disorders. Psychopharmacology, 219(4), 1133–1140. https://doi.org/10.1007/s00213-011-2449-3

4. Cheng, D., Spiro, A. S., Jenner, A. M., Garner, B., & Karl, T. (2014). Long-Term Cannabidiol Treatment Prevents the Development of Social Recognition Memory Deficits in Alzheimer’s Disease Transgenic Mice. Journal of Alzheimer’s Disease, 42(4), 1383–1396. https://doi.org/10.3233/jad-140921

5. Bloomfield, M. A. P., Green, S. F., Hindocha, C., Yamamori, Y., Yim, J. L. L., Jones, A. P. M., . . . Freeman, T. P. (2020). The effects of acute cannabidiol on cerebral blood flow and its relationship to memory: An arterial spin labelling magnetic resonance imaging study. Journal of Psychopharmacology, 34(9), 981–989. https://doi.org/10.1177/0269881120936419

6. Morgan, C. J. A., Freeman, T. P., Hindocha, C., Schafer, G., Gardner, C., & Curran, H. V. (2018). Individual and combined effects of acute delta-9-tetrahydrocannabinol and cannabidiol on psychotomimetic symptoms and memory function. Translational Psychiatry, 8(1). https://doi.org/10.1038/s41398-018-0191-x

7. Hindocha, C., Freeman, T. P., Grabski, M., Stroud, J. B., Crudgington, H., Davies, A. C., . . . Curran, H. V. (2018). Cannabidiol reverses attentional bias to cigarette cues in a human experimental model of tobacco withdrawal. Addiction, 113(9), 1696–1705. https://doi.org/10.1111/add.14243

8. Batalla, A., Bos, J., Postma, A., & Bossong, M. G. (2021). The Impact of Cannabidiol on Human Brain Function: A Systematic Review. Frontiers in Pharmacology, 11. Published. https://doi.org/10.3389/fphar.2020.618184

9. Thompson, M. D., Martin, R. C., Grayson, L. P., Ampah, S. B., Cutter, G., Szaflarski, J. P., & Bebin, E. M. (2020). Cognitive function and adaptive skills after a one-year trial of cannabidiol (CBD) in a pediatric sample with treatment-resistant epilepsy. Epilepsy & Behavior, 111, 107299. https://doi.org/10.1016/j.yebeh.2020.107299

10. Osborne, A. L., Solowij, N., & Weston-Green, K. (2017). A systematic review of the effect of cannabidiol on cognitive function: Relevance to schizophrenia. Neuroscience & Biobehavioral Reviews, 72, 310–324. https://doi.org/10.1016/j.neubiorev.2016.11.012

11. Bigdeli, M. R., & Khaksar, S. (2017). Correlation Between Cannabidiol-Induced Reduction of Infarct Volume and Inflammatory Factors Expression in Ischemic Stroke Model. Basic and Clinical Neuroscience Journal, 8(2), 139–146. https://doi.org/10.18869/nirp.bcn.8.2.139

12. Esposito, G., Scuderi, C., Valenza, M., Togna, G. I., Latina, V., de Filippis, D., . . . Steardo, L. (2011). Cannabidiol Reduces Aβ-Induced Neuroinflammation and Promotes Hippocampal Neurogenesis through PPARγ Involvement. PLoS ONE, 6(12), e28668. https://doi.org/10.1371/journal.pone.0028668

13. Campos, A. C., Ortega, Z., Palazuelos, J., Fogaça, M. V., Aguiar, D. C., Díaz-Alonso, J., . . . Guimarães, F. S. (2013). The anxiolytic effect of cannabidiol on chronically stressed mice depends on hippocampal neurogenesis: involvement of the endocannabinoid system. International Journal of Neuropsychopharmacology, 16(6), 1407–1419. https://doi.org/10.1017/s1461145712001502

14. Scheyer, A. F., Melis, M., Trezza, V., & Manzoni, O. J. (2019). Consequences of Perinatal Cannabis Exposure. Trends in Neurosciences, 42(12), 871–884. https://doi.org/10.1016/j.tins.2019.08.010

15. Hurd, Y. L., Manzoni, O. J., Pletnikov, M. V., Lee, F. S., Bhattacharyya, S., & Melis, M. (2019). Cannabis and the Developing Brain: Insights into Its Long-Lasting Effects. The Journal of Neuroscience, 39(42), 8250–8258. https://doi.org/10.1523/jneurosci.1165-19.2019

16. Thompson, M. D., Martin, R. C., Grayson, L. P., Ampah, S. B., Cutter, G., Szaflarski, J. P., & Bebin, E. M. (2020b). Cognitive function and adaptive skills after a one-year trial of cannabidiol (CBD) in a pediatric sample with treatment-resistant epilepsy. Epilepsy & Behavior, 111, 107299. https://doi.org/10.1016/j.yebeh.2020.107299

17. Linge, R., Jiménez-Sánchez, L., Campa, L., Pilar-Cuéllar, F., Vidal, R., Pazos, A., . . . Díaz, L. (2016). Cannabidiol induces rapid-acting antidepressant-like effects and enhances cortical 5-HT/glutamate neurotransmission: role of 5-HT1A receptors. Neuropharmacology, 103, 16–26. https://doi.org/10.1016/j.neuropharm.2015.12.017

18. Carrier, E. J., Auchampach, J. A., & Hillard, C. J. (2006). Inhibition of an equilibrative nucleoside transporter by cannabidiol: A mechanism of cannabinoid immunosuppression. Proceedings of the National Academy of Sciences, 103(20), 7895–7900. https://doi.org/10.1073/pnas.0511232103