Trajectory of adolescent cannabis use on addiction vulnerability

Abstract

The adolescent brain is a period of dynamic development making it vulnerable to environmental factors such as drug exposure. Of the illicit drugs, cannabis is most used by teenagers since it is perceived by many to be of little harm. This perception has led to a growing number of states approving its legalization and increased accessibility. Most of the debates and ensuing policies regarding cannabis were done without consideration of its impact on one of the most vulnerable population, namely teens, or without consideration of scientific data. We provide an overview of the endocannabinoid system in relation to adolescent cannabis exposure and provide insights regarding factors such as genetics and behavioral traits that confer risk for subsequent addiction. While it is clear that more systematic scientific studies are needed to understand the long-term impact of adolescent cannabis exposure on brain and behavior, the current evidence suggests that it has a far-reaching influence on adult addictive behaviors particularly for certain subsets of vulnerable individuals.

Age-Dependent Effects of Cannabinoids on Neurophysiological, Emotional, and Motivational States

“…Clinical and epidemiological studies have documented a significant link between repeated early cannabis exposure and an increased risk of other illicit drug use [17]. According to the phenotypic causation-"gateway model"-early initiation of cannabis use might be a risk factor for the consumption of other drugs of abuse [103], though the alternative "correlated liabilities model" proposes that cannabis use and other illicit drug use is influenced by correlated genetic and environmental factors [104].…”

“…However, animal studies suggest that the association may reflect neurobiological disturbances caused by early cannabis exposure that make individuals more vulnerable to the reinforcing effects of other drugs. In fact, there is evidence suggesting a causal relationship between early cannabis exposure and use or abuse of other addictive substances later in life [17,36]. Ellgren et al [106], in a study performed on male rats demonstrated that exposure to THC in adolescent animals produced an increase in heroin self-administration, preproenkephalin mRNA expression and functionality of µ-opioid receptors in adulthood.…”

“…In addition, pharmacological studies have shown that cannabinoids can induce a full range of transient positive, negative, and cognitive symptoms in healthy individuals that are similar to those seen in schizophrenia. Despite most of the current research has focused on the effects of cannabis on psychosis and schizophrenia, there is also increasing evidence indicating a close relationship between cannabis consumption and an increased risk for depression, anxiety disorders, and drug addiction [13,15,[28][29][30].…”

“…There is evidence indicating that during this sensitive period exposure to drugs may have a greater impact on neurocognition compared to adult exposure [40]. A "window of vulnerability" appears to exist during the adolescent period regarding the onset of certain neuropsychiatric disorders such as schizophrenia and the effects of drugs of abuse [14,17,18,41,42]. In particular, both human and animal studies indicate that cannabis use during adolescence may produce cognition impairments [26,27] and depressive symptoms, and may increase the risk to develop psychiatric and substance abuse disorders [3,18,39,43].…”

Lifestyle and Health Risk Behaviours among Elbasan Students

“…A review of more than 120 studies strongly suggests that consuming cannabis during adolescence interferes with natural brain development and may hardwire some teens to develop addictions in adulthood. Cannabis consumption during teenage years could also make some individuals more susceptible to suffering from schizophrenia -mainly teens that have a genetic predisposition to the mental illness [33].…”