Introduction
Cannabis is an illicit drug that is widely used worldwide. It has been estimated that about 181 million people use it all over the world (Archie & Cucullo, 2019). This drug is obtained from three types of the cannabis plant called Cannabis indica, Cannabis sativa, and Cannabis ruderalis (Archie & Cucullo, 2019). These plants have different contents and vary in the amount of main active ingredients – cannabidiol (CBD) and D9-tetrahydrocannabinol (THC) (Archie & Cucullo, 2019). Cannabis has several positive effects that allow for medical use as an anticonvulsant, antioxidant, neuroprotective, and anti-inflammatory agent (Archie & Cucullo, 2019). However, this drug’s benefits do not outweigh its detrimental effects, including cognitive impairments, mental health disorders, poor coordination, and addiction development, among others. This paper aims to discuss the biological, cognitive, emotional, and behavioral advantages and disadvantages of cannabis use at different stages of human development. Although this drug has certain medical benefits, it should be used with caution since its effects differ depending on the dose, content, and the onset of cannabis use.
The Biological Advantages and Disadvantages of Cannabis Use
Cannabinoids – active constituents of cannabis – affect the human body by interacting with the endocannabinoid system (ECS). ECS comprises two receptor types: CB1 and CB2; CB1 receptors are mainly found in the brain and spinal cord, and CB2 are located in the immune and peripheral nervous systems (Archie & Cucullo, 2019). When a person consumes cannabis, cannabinoids from the plant interfere with the normal functioning of the ECS, thus causing various neurological effects. For example, THC usually binds with CB1 receptors in the body. Since CB1 receptors are situated in brain regions responsible for memory, cognition, anxiety, and motor coordination, cannabis use may impair these functions (Archie & Cucullo, 2019). In contrast, CBD binds to CB2 receptors responsible for anti-inflammatory activity (Archie & Cucullo, 2019). As a result, this constituent of cannabis can be used in medicine to reduce inflammation.
Cannabis use has different effects depending on the human developmental stage. Prenatal exposure to this drug may negatively influence the health of the individual in adulthood. For example, research has revealed that pregnant women who consume cannabis alter the DRD2 gene expression in fetuses’ mesocorticolimbic brain regions (Hurd et al., 2019). Consequently, it affects the onset and trajectory of mental disorders because these brain regions are responsible for emotional regulation, motivation, and cognition (Hurd et al., 2019). In addition, when a pregnant or breastfeeding woman uses cannabis, it may influence her child’s prefrontal cortex development, which may lead to cognitive and behavioral problems in adulthood (Hurd et al., 2019). Thus, exposure to cannabinoids in the prenatal stage and infancy has detrimental long-term effects on the development of the individual.
Adolescence is another critical period during which cannabis use can interfere with normal development. In adolescence, the activity of the ECS reaches its peak; in particular, this system fine-tunes the mesolimbic dopamine pathway to regulate behaviors associated with rewards (Hurd et al., 2019). The use of cannabis during this developmental stage may affect the reward pathway and increase adolescents’ vulnerability to drug addiction. Further, cannabis use in adolescence decreases white matter connectivity and integrity in temporal and frontal lobes, thus causing psychological and cognitive impairments (Suryadevara et al., 2017). Hence, young people’s consumption of cannabis is detrimental to their development and maturation.
Despite the identified biological disadvantages of cannabis use, researchers distinguish several health benefits of this drug. In particular, it has been found useful for treating amyotrophic lateral sclerosis (ALS). ALS is a rapidly progressing neurodegenerative disease affecting the motor neurons of the brain stem and spinal cord, and inflammation has an important role in this disease progression (Suryadevara et al., 2017). Therefore, cannabinoids help slow down the development of ALS by reducing inflammation (Suryadevara et al., 2017). Further, studies have identified that Parkinson’s disease is associated with the dysregulation of the ECS (Crippa et al., 2019). As a result, the use of cannabis, which affects the ECS, can alleviate several symptoms of Parkinson’s disease, such as sleep disturbances, psychosis, and pain (Crippa et al., 2019). Alzheimer’s disease can also be treated with cannabis since its anti-inflammatory, antioxidant, and neuroprotective effects are hypothesized to reduce beta-amyloid toxicity (Suryadevara et al., 2017). Thus, cannabis has potential benefits for older adults with various neurological disorders.
The Cognitive Advantages and Disadvantages of Cannabis Use
Cognitive impairments caused by the use of marijuana are varied. Evidence indicates that multiple aspects of attention and memory are frequently affected (Suryadevara et al., 2017). In addition, cannabis use may result in poor decision-making, impaired response inhibition and accuracy, slower reaction times, reduced speed of information processing, and poor planning (Suryadevara et al., 2017). Studies also show that people can experience a certain recovery in cognitive functions such as learning and verbal processing after prolonged abstinence; however, difficulty with dealing with attention tasks may remain (Suryadevara et al., 2017). Thus, marijuana causes significant cognitive impairments that can be reversed after long abstinence.
Cannabis negatively affects cognitive functions in individuals who have been prenatally exposed to this drug. In preschool age, such individuals may have slightly impaired short-term memory, sustained attention, and verbal processing (Grant et al., 2018). It was found that heavy use of cannabis during pregnancy led to decreased academic performance, learning, memory, visual analysis, and impulse control in children when they reached middle school age (Grant et al., 2018). In adulthood, such individuals may have deficits in executive functions that include cognitive processes necessary to manage attention, set goals, and exert inhibitory control (Grant et al., 2018). Hence, cannabis use during pregnancy, especially heavy, can negatively influence individuals’ cognitive functioning later in life.
Regarding adolescents, the available scientific evidence does not allow for making strong conclusions about the differences between their response to cannabis use and that of adults. However, the study conducted by Gorey et al. (2019) enabled scholars to develop several hypotheses based on the research findings. First, among frequent users of cannabis, adolescents may be subject to greater cognitive impairments than adults (Gorey et al., 2019). Second, after cannabis intoxication, adults may experience a greater reduction in inhibitory control and craving than adolescents (Gorey et al., 2019). These findings indicate that both adolescents and adults may have cognitive impairments as a result of cannabis use, but the effects on adolescents can be more considerable.
The research evidence related to the impact of cannabis use on older adults is scarce. A systematic review conducted by Scott et al. (2019) revealed that the existing studies point to the modest effects of marijuana on the cognitive function of people over 50. As for the cognitive benefits of cannabis, there is no scientific evidence that this drug can improve any of the cognitive functions. For example, a study investigating the influence of CBD on cognitive function in patients with schizophrenia found statistically insignificant improvement in this parameter (Weston-Green, 2019). Another research exploring the effectiveness of CBD for improving the symptoms of Huntington’s disease showed that this drug did not result in better cognitive function (Weston-Green, 2019). Thus, one may conclude that cannabis use may impair cognitive function but cannot enhance it.
The Emotional Advantages and Disadvantages of Cannabis Use
Cannabis is usually used for recreational purposes due to its emotional benefits. Frequently mentioned subjective effects of marijuana include relaxation, stress relief, and positive mood (Childs et al., 2017). However, a study conducted by Childs et al. (2017) revealed that these feelings occurred after taking a low dose of cannabis. High doses, on the contrary, led to an increase in anxiety and negative mood. These findings are consistent with the results of other studies, which discovered that cannabis, and its component THC in particular, helps reduce fear (Maroon & Bost, 2018). This evidence indicates that low doses of cannabis can help individuals cope with stress.
Another study aimed to assess the impact of marijuana on people’s perception of rewards and identify whether the main cannabis components – THC and CBD – differed in their effect on reward processing. Freeman et al. (2018) investigated individuals’ response to music, which is a rewarding experience, after cannabis use by tracking their brain activity. Contrary to their expectations, the researchers found that THC dampened the rewarding effect of music in participants instead of increasing it. This impact of cannabis is similar to that of depression, in which response to music is also blunted (Freeman et al., 2018). In contrast, CBD enhanced sound perception and offsets certain negative effects of THC. These findings suggest that cannabis with high content of THC has a negative impact on individuals’ emotions because it reduces the pleasure of rewarding experiences.
Cannabis use may particularly affect the emotional state of children and adolescents. Although there is no scientific evidence of the emotional effects of cannabis in human individuals exposed to this drug in utero, animal studies show that prenatally exposed rats had deficits in social behaviors and anxiety-like symptoms (Grant et al., 2018; Hurd et al., 2019). A human study of cannabis use in adolescents showed that young people with cannabis addiction had a reduced ability to recognize facial expressions, especially fearful and sad ones (Blair et al., 2021). In addition, such adolescents demonstrated aggression, which is linked to their impaired facial recognition (Blair et al., 2021). Facial recognition is a crucial ability for the establishment of healthy interpersonal relationships and appropriate involvement in social interactions. When this function is reduced, people become less sensitive toward the distress of others, which causes them to engage in aggressive and harmful behaviors. Hence, cannabis undermines adolescents’ emotional functioning, which takes a toll on their social life.
The Behavioral Advantages and Disadvantages of Cannabis Use
The neurological impact of cannabis is manifested in certain behavioral effects. In particular, people consuming marijuana experience a decrease in motivation (Sorkhou et al., 2021). This may be explained by the previously mentioned finding revealing that cannabis reduces individuals’ response to rewards. Further, this drug negatively affects psychosocial behaviors, which is demonstrated by reduced occupational and educational achievements (Sorkhou et al., 2021). For example, in adolescents, cannabis use was associated with a decreased likelihood of attending classes, completing homework, and planning to pursue a degree (Sorkhou et al., 2021). The onset and duration of cannabis use significantly impact people’s psychosocial functioning. Heavy cannabis use in adolescence results in an increased risk of being unemployed, having a low income, relying on welfare, and being arrested (Sorkhou et al., 2021). Moreover, studies show that those who began using marijuana in adolescence and continued to use it in adulthood experienced the worst psychosocial functioning at the age of 35 (Sorkhou et al., 2021). This is in comparison to their non-using peers and those who used cannabis only in adolescence or began using it in adulthood.
Cannabis use also affects driver behavior, increasing the risks of motor vehicle accidents. Research shows that, due to slow reaction times, cannabis-intoxicated drivers may poorly respond to unexpected events (Compton, 2017). In addition, they have difficulties tracking the road, planning the route, and maintaining attention (Compton, 2017). Notably, the effect of marijuana on driver behavior is different from that of alcohol. Cannabis users usually drive with reduced mean speeds and maintain an increased distance from a car ahead, while alcohol-intoxicated individuals often exceed the speed limit and drive with a great speed variability (Compton, 2017). When alcohol and cannabis are used simultaneously, marijuana tends to offset the negative effects of alcohol, reducing the mean driving speed (Compton, 2017). Overall, although cannabis seems to have milder negative effects on drivers than alcohol, it poses significant risks to safety on the road.
Special attention should be paid to the influence of maternal cannabis use on children’s behavioral outcomes. Research shows that infants born to moderate and heavy-using mothers had poorer visual habituation and increased startle and tremor (Grant et al., 2018). In addition, they demonstrated a reduced time of quiet sleep and increased body movements during sleep (Grant et al., 2018). In middle school age, prenatally exposed children may experience increases in delinquent behavior, impulsivity, and hyperactivity (Grant et al., 2018). In adolescence, such individuals maintain a higher risk of delinquent behavior and are vulnerable to the early onset of cannabis use (Grant et al., 2018). These findings suggest that in utero exposure to cannabis has long-term detrimental effects on the subsequent behaviors of the individual.
While there is strong evidence proving the negative influence of cannabis on behavior, there are also some benefits. A study conducted by Fleury-Teixeira et al. (2019) found that CDB-enriched cannabis can improve conduct in patients with autism spectrum disorder (ASD). This drug was particularly helpful for enhancing sleep quality and reducing hyperactivity. Therefore, cannabis rich in CBD can potentially alleviate the symptoms of ASD.
Conclusion
The neurological effects of cannabis use vary depending on users’ age, the content of the drug, and the dose. It has been found that prenatal and perinatal exposure have a long-term negative impact on the subsequent human development in all aspects: biological, cognitive, emotional, and behavioral. Therefore, pregnant and breastfeeding women should abstain from using cannabis to prevent developmental impairments in their children. In adolescence, the use of cannabis is also associated with adverse effects because young people’s brain and body systems undergo important changes. The negative impact of the early onset of cannabis use is aggravated if it continues into adulthood. In adults, cannabis use may help reduce stress and relax, but only if low doses are taken. In the elderly, cannabis shows the greatest benefits since it can improve symptoms of various neurological diseases prevalent in this population, for example, Parkinson’s disease and Alzheimer’s disease. Finally, among the main components of cannabis, THC appears to be responsible for negative effects, while CBD offsets these influences and brings medical benefits.
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