You may know THC as the chemical in cannabis that provides the relaxed feeling. While some use it for medicinal reasons, others wonder if it’s safe. In fact, how does THC affect the central nervous system?
The CNS (central nervous system) comprises the brain and the spinal cord. It’s the body’s processing centre. It sends messages via nerve cells to the muscles, prompting movement.
It also receives information, generating a response that controls the body’s function.
Tetrahydrocannabinol (THC), is identical to anandamide, a natural chemical in the brain. Once attached to the neurotransmitter, it can improve an individual’s mood. Many refer to it as the ‘miracle wonder’ because of this.
Anandamide, like THC, attaches to the CB1 receptors in the CNS. The clinical impacts include the release of dopamine.
This cannabinol attaches to receptors in the brain responsible for thinking. This area also controls memory and coordination.
Understanding THC and the endocannabinoid system
THC is one of over a hundred cannabinoids found in cannabis. Its chemical structure mimics that of CBD. But, how does THC affect the central nervous system?
THC easily interacts with the body. This relationship is because of its similarities to the natural cannabinoids. It binds to the CB1 and CB2 receptors found throughout the body.
The central nervous system houses the CB1 and the peripheral nervous system, to the CB2.
Endocannabinoid, the cannabinoid receptors, and enzymes together form the endocannabinoid system (ECS). To fully understand the role of the ECS requires more research.
The results from studies already conducted, has shown it plays a role in:¹
- Mood
- Motor control
- Metabolism
- Muscle formation
- Liver function
- Inflammation
- Learning and memory
- Skin and nerve function
These functions help the body maintain homeostasis. It ensures that everything remains fully functional and balanced amidst fluctuating external conditions.
Injury, fever, or inflammation can trigger a disparity. When this imbalance occurs, the endocannabinoids attach to the receptors where needed.
The ECS then self-regulates and restores balance. Thereafter, the enzymes break down the cannabinoids as it’s no longer needed.
THC interaction with the ECS is very similar. It attaches to both the CB1 and CB2 causing a range of effects throughout the body.
Acute effects of THC on the CNS
THC interaction with the ECS affects the hippocampus and orbitofrontal cortex. These areas play a crucial role in focus and attention. It also creates memory impairment, with new memories forming.
Higher doses could cause short-term effects such as hallucinations and delusions.
Another area of the brain impacted is the cerebellum and basal ganglia. THC may disrupt balance, coordination, and posture.
Other effects relating to this cannabinoid is the stimulation of neurons that release dopamine.² This hormone rewards the behaviour of the individual, encouraging them to repeat it.
THC has a few common acute symptoms. These signals include feelings of euphoria and an enhanced sensory perception. Colours may appear brighter and sound louder.
They could also feel more cheerful and with a wave of uncontrollable laughter.
There are various factors that may lead to THC intoxication. High doses, the age of the individual and their tolerance level also play a role.
The user risks becoming intoxicated. The possibility depends on the method of consumption. Inhaling THC increases the chances of being high. It allows the cannabinoid to enter the bloodstream faster through the lungs.
The effects of oral ingestion take much longer. Once ingested, it passes through the digestive system. The liver then metabolises it before it enters the bloodstream.
Acute THC intoxication can result in anxiety, paranoia and episodes of psychosis.³ Other neurological impairments may include seizures and tremors. The severity will vary from one person to another.
Those new to THC consumption could experience more acute effects.
Long-term effects of THC on CNS
THC has some long-term effects. How does THC affect the central nervous system during an extended period?
This impact may affect both the cognitive function and brain structure. Research shows it could reduce the volume of gray matter in the orbitofrontal cortex.⁴
It’s the part of the brain responsible for the reward system.
THC’s relaxing effects have positive and negative effects on the CNS. It helps to ease anxiety and also assists with insomnia. These factors support the claims that cannabis is a depressant.⁵
The negative effects include slurred speech, blurred vision and temporary loss of memory. Extended use can result in long-term effects. These reactions can impair concentration and the ability to learn.
Some studies indicate that regular use may cause symptoms of psychosis. It may also delay its recovery. These are more probable in those with a family history of psychological illness.
THC could increase the risk in certain psychiatric disorders:
- Bipolar disorder: Individuals using THC risk developing bipolar. The chances are higher in those with a history of cannabis use disorder.
- Anxiety: Social anxiety disorder can also develop as a result of THC use.
- Schizophrenia: A greater risk of schizophrenia and other psychotic illnesses exists.⁶ The probability is greater when using high levels of THC.
- Depression: Those who previously had cannabis use disorder could chance developing depression.
With cognitive function, evidence has shown that using cannabis at an early age can lower IQ.⁷ When consuming THC from a young age and for long periods can decrease cognitive function.
THC has neuroprotective properties. Research indicates that it can prevent damage to neurons during brain injuries.
These afflictions, if not treated, can have serious implications. Low doses of THC a few days prior and after brain injury can provide neuroprotection:
- Cerebral ischemia: A condition that occurs when there’s insufficient blood flow to the brain. A blockage could restrict the circulation.
- Glutamate-induced excitotoxicity: Excess glutamate (a neurotransmitter) can cause brain cell damage or destroy it.
- Oxidative stress: This condition occurs when there’s an imbalance between free radicals and antioxidants.
THC and neurodevelopment
THC can have a significant impact on neurodevelopment. Exposure during adolescence can prolong the effects. It can affect the formation and function of the brain.
Impaired brain development results in a decrease in social behaviour. It can also alter the motivational processes. THC exposure in adolescence can cause a deficit in the working memory of an adult.
The effects also include cognitive and behavioural difficulties. These may result in mental health conditions too, affecting their academic performance.
The long-term consequences may linger even after the individual has ceased using THC. One of these after effects is a reduction in their IQ. These individuals have an increased risk of developing anxiety and depression.
To reduce the risks associated with young individuals’ use of THC, there are a few factors to consider:
- Discuss safe ways of using cannabis and THC.
- Use legal and regulated products.
- Monitor usage by avoiding its frequency and intensity.
- Avoid high potent THC products.
- Encourage healthy coping mechanisms, providing support where needed.
- Seek professional help if the young individual experiences any adverse effects.
Therapeutic uses of THC
Many individuals use THC as part of a cannabis treatment plan. The Therapeutic Goods Administration (TGA) approved it for treating various conditions in Australia:
- Anxiety
- Depression
- Anorexia and wasting
- Cancer pain
- Chronic infection
- Chronic pain
- Migraines
- Fibromyalgia
- Epilepsy and seizure management
- Autism syndrome
- Multiple sclerosis
- Parkinson’s Disease
- Many other as listed by TGA⁸
Patients may use medical cannabis to treat these conditions. There’s limited evidence in proving its effectiveness. To fully understand its benefits and risks requires more research.
When THC binds to the receptors, the interaction triggers the release of neurotransmitters.⁹ This action produces the required physiological effects.
The cannabinoid also has anti-inflammatory properties. It facilitates the increase of M2 macrophages. This cell secretes cytokines to help reduce inflammation.
The pain-relieving effects of the THC in medical cannabis minimises its perception. It does this by altering the pain pathways to the brain.
The therapeutic uses and effects vary, depending on the administration and dose. Medical professionals should carefully consider the benefits and potential risks per patient.
Clinical considerations include assessing the patient’s medical history and individual needs. The health practitioner should inform the individual of potential adverse effects. Then closely monitor them for these reactions.
The need for further research and standardisation of medical cannabis products still exists. To ensure the safety of all patients, experts should regulate the use of THC in a clinical setting.
Clinical guidelines and recommendations
As health professionals, ensure that THC products prescribed have TGA approval. The product should have clinical evidence supporting the patient’s medical condition.
During treatment, monitor for any adverse effects. You should then report this information to TGA within 15 calendar days. TGA has developed clinical guidelines to assist these professionals in prescribing medicinal cannabis.¹⁰
Each state and territory may have their own requirements regarding THC prescription. Medical professionals should familiarise themselves with this.
Various medical authorities provide expert advice and support to health practitioners. Local health districts have medicine information services. They provide the necessary help which assists with harm reduction.
The John Hunter Hospital Pharmacy Department in NSW provides medicinal cannabis prescribing advice.¹¹
Those recommending THC products should remain informed of ongoing clinical trials. They should keep abreast of any new developments that may arise in this industry.
Health professionals should enforce patient education regarding medicinal cannabis. You need to ensure they fully understand the benefits and risks. The Pharmacy Guild of Australia encourages safe and professional drug-checking services.
These options ensure safe use of this personalised medicine. It also reduces the risk of harm.
Future research directions
There are many knowledge gaps in the effectiveness of THC. Future research will help in providing more information. The effects of it on the brain and impact on mental health are vital to all health professionals.
The potential risks will also be useful for those in marginalised groups and youth. The interaction with other substances also requires more research.
Patients and health professionals will benefit from the effects of THC on the CNS. Understanding all the potential risks and benefits can assist with developing therapeutic applications.
Knowing the genetic variability helps with understanding how THC affects the CNS. Also vital is how genetic factors may influence cannabis use disorder.
Understanding the safety of long-term use of THC is important. It helps in discovering the potential risks and benefits. The neuroprotective effects of THC provide useful information. It assists with determining the therapeutic benefits.
Experts use fMRI (Functional Magnetic Resonance Imaging) to study THC’s effects on CNS. Structural Magnetic Resonance Imaging (sMRI) helps researchers understand the structural changes from THC.
Neuroimaging helps health professionals better understand the connection between THC and the CNS.
Ongoing clinical trials and studies will help clarify the therapeutic indications of THC.
The complex relationship between THC and the CNS
In conclusion, THC has many medicinal benefits and potential risks. The key points cover the impact on CNS after long-term use and what knowledge gaps exist.
To ensure informed use among patients, health professionals should consider all their information. This data includes family history, patients’ medical needs, and any adverse effects.
To fully understand how the patient can benefit, ongoing research is crucial. The doctor’s perspective of how THC interacts with the CNS can also contribute to this success.
The shortcomings and effectiveness of THC will ensure safe treatment options.
As a health professional, remain informed. Keep abreast of all things related to THC. Connect with Planted and enrol for a course that will best suit you.
References:
- Zou, S. and Kumar, U. (2018). Cannabinoid Receptors and the Endocannabinoid System: Signaling and Function in the Central Nervous System. International Journal of Molecular Sciences, [online] 19(3), p.833. doi:https://doi.org/10.3390/ijms19030833.
- National Institute on Drug Abuse (2019). Cannabis (Marijuana) DrugFacts. [online] National Institute on Drug Abuse. Available at: https://nida.nih.gov/publications/drugfacts/cannabis-marijuana.
- National Institute on Drug Abuse (2019). Cannabis (Marijuana) DrugFacts. [online] National Institute on Drug Abuse. Available at: https://nida.nih.gov/publications/drugfacts/cannabis-marijuana.
- Battistella, G., Fornari, E., Annoni, J.-M., Chtioui, H., Dao, K., Fabritius, M., Favrat, B., Mall, J.-F., Maeder, P. and Giroud, C. (2014). Long-Term Effects of Cannabis on Brain Structure. Neuropsychopharmacology, [online] 39(9), pp.2041–2048. doi:https://doi.org/10.1038/npp.2014.67.
- Murray, J.B. (1986). Marijuana’s effects on human cognitive functions, psychomotor functions, and personality. The Journal of general psychology, [online] 113(1), pp.23–55. doi:https://doi.org/10.1080/00221309.1986.9710540.
- National Academies of Sciences, Engineering, and Medicine, Health and Medicine Division, Board on Population Health and Public Health Practice and Evidence, A. (2017). Mental Health. [online] Nih.gov. Available at: https://www.ncbi.nlm.nih.gov/books/NBK425748/.
- PubMed. (n.d.). meier caspi persistent cannabis - Search Results - PubMed. [online] Available at: https://pubmed.ncbi.nlm.nih.gov/?term=meier+caspi+persistent+cannabis [Accessed 13 Jun. 2024].
- honahlee. (n.d.). Medical Conditions Treated By Cannabis (And Side Effects). [online] Available at: https://honahlee.com.au/articles/conditions-medical-cannabis-treats/.
- Chayasirisobhon, S. (2020). Mechanisms of Action and Pharmacokinetics of Cannabis. The Permanente Journal, 24(5). doi:https://doi.org/10.7812/tpp/19.200.
- Queensland Health (2017). Prescribing medicinal cannabis in Queensland | Queensland Health. [online] Qld.gov.au. Available at: https://www.health.qld.gov.au/public-health/topics/medicinal-cannabis/prescribing.
- www.medicinalcannabis.nsw.gov.au. (n.d.). Clinical guidance for cannabis medicine prescribers | Centre for Medicinal Cannabis Research and Innovation. [online] Available at: https://www.medicinalcannabis.nsw.gov.au/health-professionals/information-for-cannabis-medicine-prescribers [Accessed 13 Jun. 2024].