A longitudinal analysis of the effects of a DRD4 polymorphism on marijuana use

An Illustrative Review of Substance Use-Specific Insights From the National Longitudinal Study of Adolescent to Adult Health

PURPOSE

The purpose of this illustrative, thematic review was to demonstrate the utility of data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) for substance use research and to describe substance use-specific insights gained from Add Health research over the past 2 decades.

METHODS

We searched multiple electronic databases (PubMed, PsycInfo, and Web of Science) and selected an illustrative sample of 40 articles that used Add Health data and longitudinally examined a measure of alcohol, marijuana, or illicit drug use or prescription drug misuse as the exposure or outcome in association with diverse domains of additional factors assessed (social, emotional, behavioral, contextual, biological, and genetic).

RESULTS

Included articles identified several key associations between substance use behaviors and additional factors from a wide range of domains. For example, results from several studies indicated that experiences of sexual violence, adolescent dating violence, and intimate partner violence are associated with an increased likelihood of later prescription opioid misuse, heavy drinking, and marijuana use, with some differences by biological gender and race/ethnicity. Results from other studies showed that bidirectional associations between substance use and mental health differ by specific type of substance and mental health condition.

DISCUSSION

Existing research using Add Health data has provided valuable insights regarding substance use by leveraging the study's longitudinal design, the prospective nature of data collection, the breadth and depth of substance use questions assessed from adolescence to adulthood, the size and diversity of the cohort, and the wide range of additional factors measured over time.

Depression Onset in Long-term Adolescent Cannabinoid Use: A Neurobiological Review

Escalating cannabis use may be linked to decreased motivation and anhedonia, which are symptoms of depression. Adolescent cannabis users with subthreshold depressive symptoms such as reduced motivation may be susceptible to the development of significant anhedonia in addition to impaired emotional development. The main issue regarding depression within the context of cannabis use is whether or not there is a neurobiological basis linking the two variables.

A Medical Subject Headings (MeSH) function PubMed search using the keywords “cannabis, depression, adolescence, endocannabinoid, and temperament” returned 1,109 articles. Data were included from studies that satisfied the following criteria: (i) published within the last 10 years (older studies were included based on relevance), (ii) on adolescent subjects (animal or human), (iii) published in English, (iv) journal articles, systematic reviews, meta-analyses, clinical trials, observational studies (animal or human), (v) on subjects who had unipolar depression with no comorbidities, and (vi) on subjects who used cannabis [with no confounding variables such as the use of ethanol, nicotine, cocaine, lysergic acid diethylamide (LSD), and heroin; and no medical conditions such as comorbid psychosis, mania, or autism].

Depressive symptoms in cannabinoid users were a common co-occurrence partly explained by pleiotropic linkage of genetic locus identified on chromosome 11q23.1-q23.2 and comprises the gene sequence nuclear cell adhesion molecule 1-tetratricopeptide repeat domain 12-ankyrin repeat and kinase domain containing 1-dopamine receptor D2 (NCAM1-TTC12-ANKK1-DRD2). The relationship between the two is not invariant and is influenced by polymorphic DRD, endocannabinoid receptor (CNR), and 5-HT genes. Anhedonia seemed to be the most important symptom. Cannabinoid-induced long-term neuroplastic changes, particularly in the dorsal striatum, is a possible mechanism resulting in anhedonia and long-term effects on motivation.

Does cannabis affect dopaminergic signaling in the human brain? A systematic review of evidence to date

A significant body of epidemiological evidence has linked psychotic symptoms with both acute and chronic use of cannabis. Precisely how these effects of THC are mediated at the neurochemical level is unclear. While abnormalities in multiple pathways may lead to schizophrenia, an abnormality in dopamine neurotransmission is considered to be the final common abnormality. One would thus expect cannabis use to be associated with dopamine signaling alterations. This is the first systematic review of all studies, both observational as well as experimental, examining the acute as well as chronic effect of cannabis or its main psychoactive ingredient, THC, on the dopamine system in man. We aimed to review all studies conducted in man, with any reported neurochemical outcomes related to the dopamine system after cannabis, cannabinoid or endocannabinoid administration or use. We identified 25 studies reporting outcomes on over 568 participants, of which 244 participants belonged to the cannabis/cannabinoid exposure group. In man, there is as yet little direct evidence to suggest that cannabis use affects acute striatal dopamine release or affects chronic dopamine receptor status in healthy human volunteers. However some work has suggested that acute cannabis exposure increases dopamine release in striatal and pre-frontal areas in those genetically predisposed for, or at clinical high risk of psychosis. Furthermore, recent studies are suggesting that chronic cannabis use blunts dopamine synthesis and dopamine release capacity. Further well-designed studies are required to definitively delineate the effects of cannabis use on the dopaminergic system in man.