Fetal Exposure to Cannabinoids: Exposure, Methylation and Neurodevelopmental Effects
Fetal Exposure to Cannabinoids: Exposure, Methylation and Neurodevelopmental Effects
Cannabis is a very popular drug for both recreational and medicinal use. An estimated 20% of
 adults in the United States report using cannabis in the past month, and this number
 continues to increase each year. As of 2018, medical use of cannabis is legal in 33 states
 and the District of Columbia. Recreational use is legal in 10 states, and it is
 decriminalized in 15 states. Hemp-derived cannabidiol (CBD) is legal in all states. Due to
 the rapidly changing legal status across the country, the demand for cannabinoids (which are
 specific components of cannabis), such as THC and CBD, are also rapidly increasing. Studies
 have shown a significant increase in marijuana use among pregnant and parenting women
 following state-wide legalization, and this could have significant implications for the
 health and development of children born to these women.

 While there is a growing effort to evaluate the health effects of cannabinoids, especially
 during pregnancy, there is still relatively little known about the long term
 neurodevelopmental outcomes, such as emotional regulation, attention, and intelligence, in
 children born to mothers who used any sort of cannabinoid during pregnancy. The few studies
 that have been performed that look at longer term outcomes were epidemiological and
 self-reported in nature, and cannot accurately correlate neurodevelopmental outcomes with
 precise dosage and exposure levels during pregnancy.

 Importantly, the THC content of marijuana has dramatically increased in recent years, with
 THC concentration and purity being the highest in history. It is estimated that cannabis
 potency has increased 3-fold over the past 2 decades. Many of the previous studies examining
 prenatal cannabis use and fetal outcomes reflected lower potency cannabis, which is not
 relevant to today's exposure levels. Additionally, there are no published studies to-date
 that evaluate fetal exposure to CBD or neurodevelopmental outcomes in infants who were
 exposed to CBD prenatally.

 Finally, the causes behind possible neurodevelopmental changes in children exposed to
 cannabis prenatally have not been thoroughly explored, particularly in humans. It is thought
 that epigenetic modifications, or changes to DNA, may play a role in changes to the
 developing fetal brain after prenatal exposure to cannabis, but few studies have evaluated
 this quantitatively in humans.
Cannabis is a very popular drug for both recreational and medicinal use. An estimated 20% of
 adults in the United States report using cannabis in the past month, and this number
 continues to increase each year. As of 2018, medicinal use of cannabis is legal in 33 states
 and the District of Columbia. Recreational use is legal in 10 states, and it is
 decriminalized in 15 states. Hemp-derived cannabidiol (CBD) is legal in all states. Due to
 the rapidly changing legal status across the country, the demand for tetrahydrocannabinoid
 (THC) and CBD products is also rapidly increasing. Studies have shown a significant increase
 in marijuana use among pregnant and parenting women following state-wide legalization, and
 this could have significant implications for the health and development of children born to
 these women.

 Despite its widespread use, and increased interests in THC for medical treatment, significant
 gaps exist in the investigator's scientific knowledge of the pharmacology and
 pharmacokinetics of THC and its metabolites. When inhaled, THC and CBD reach maximum
 concentrations within seconds. Bioavailability varies widely and is a function of inhalation
 time, number, interval, and duration of puffs, as well as within product variability.
 Importantly, smokers have greater bioavailability of THC than non-smokers. When THC and CBD
 are orally consumed, the bioavailability is relatively low (< 20%). However, the
 lipophilicity of both THC and CBD make these compounds of great interest with respect to
 tissue distribution. CBD is more lipophilic than THC and thus more likely to be absorbed with
 topic application. THC is known to cross the placenta and can reach the fetus]. The
 metabolism of both THC and CBD is complex. Following absorption, THC and CBD are rapidly
 distributed to tissues with high blood flow. Metabolism occurs in the liver via CYP2C9,
 CYP2C19, and CYP3A4, as well as the brain, small intestine, heart and lung. Primary
 metabolites undergo glucuronidation or conjugation reactions. The elimination half-lives are
 prolonged due to the deposition of drug and metabolites in fat.

 Some previous epidemiological studies have shown that children born to mothers who report
 using THC during their pregnancy have a higher prevalence of neurodevelopmental and
 behavioral abnormalities. While these studies are sparse, there have been some studies that
 follow longitudinal cohorts worldwide. These epidemiological, survey-based studies have
 reported an increase in executive functioning deficits in infants who were exposed to THC in
 utero. These studies have also shown an increase in attention problems and hyperactivity in
 these children during early childhood and later adolescence. However, these studies have
 reported inconsistent outcomes. Some have reported negative effects on cognitive or executive
 functioning, and others have reported no significant changes. One possibility for these
 discrepancies is that survey-based epidemiological studies do not accurately capture the
 exact levels of fetal exposure due to the unreliable nature of self-reporting, making it
 difficult to accurately correlate prenatal exposure levels to neurodevelopment. This makes
 the need for a well-designed, quantitative exposure study that is followed by longitudinal
 neurodevelopmental outcome measurement imperative to determining true correlations between
 prenatal THC use and developmental outcomes in children.

 It has also previously been established that cannabis use during pregnancy can be detrimental
 to the developing fetus. Prenatal use of THC has been shown to cause low birth weight in the
 absence of any change in neonatal length or head circumference, as well as increased tremors
 and disrupted sleep patterns. It has also been correlated with an increased need for
 placement in the neonatal intensive care unit. In addition to human studies, animal studies
 have shown changes in the endocannabinoid system (ECS) in the fetal brain during development.
 The ECS is present in the developing brain from the time of 5 weeks gestation, and is
 required for proliferation, differentiation, and migration of neurons. Any changes to this
 system during development could have important implications for further neural development.
 Several studies have observed changes in postsynaptic target selectivity, differentiation of
 developing axons, and disruption of position in the ECS in animal fetuses that were exposed
 to THC in utero. These central nervous system alterations could potentially point to
 long-term neurodevelopmental changes in children born to mothers who used cannabis during
 pregnancy. However, while animal studies are able to report exact dosing levels, animal
 models of prenatal cannabinoid use often do not accurately reflect human use.

 While some detrimental effects to the fetus following prenatal cannabis use have been
 observed in both animal models and human studies, there remains the mechanistic question of
 what is causing these changes. Some studies have proposed epigenetic reprogramming that may
 occur in the mothers and the babies following prenatal cannabis use. Prior studies have
 focused on the effects of prenatal cannabis use increasing the likelihood of the children's
 substance abuse later in life, and have found positive correlations to DNA methylation and
 histone modification in these cases. Additionally, it has been shown that paternal cannabis
 use alters DNA methylation in sperm of rats and humans, which could also have important
 implications for development. However, to-date, there have not been any studies correlating
 epigenetic changes and neurodevelopmental changes in infants prenatally exposed to cannabis.

 Additionally, many of the prior human studies were done at a time when THC content in
 marijuana was not as high as is in today's market, which could have major implications for
 actual exposure levels in the fetus. The initial studies that evaluated the effects of
 prenatal cannabis use on fetal outcomes were done in the early 1990s, at a time when average
 THC potency in seized marijuana in the United States was approximately 4%. The most recently
 reported potency of seized illicit cannabis plant material is approximately 12%.
 Additionally, the ratio of psychoactive THC content to non-psychoactive cannabidiol content
 has increased from approximately 14 to 80 between 1995 and 2014. These factors suggest a need
 for more updated studies that examine the effects of current high potency levels of fetal
 exposure to cannabis, as an increase in potency may have greater effects on the developing
 fetus.

 While there have been some prior studies measuring the effects of fetal exposure to THC
 specifically, there have been no studies to-date that have evaluated the effects of CBD
 exposure on the developing fetus. CBD (also known as hemp) supposedly lacks psychoactive THC
 components, making it legal, widely available, and generally perceived to be safe.CBD is
 touted as a treatment for a number of conditions, including depression, anxiety, pain, and
 cancer. These factors, in addition to strong marketing campaigns, have most likely caused an
 increase in prenatal CBD use in recent years. A recent study conducted in mice found that CBD
 activates a large range of CYPP450 enzymes. While these data are preliminary, CYPP450
 activation raises the concern of drug-drug interactions and suggests that biologic activity
 of CBD is not fully understood. However, there are no published studies evaluating the
 effects of prenatal CBD use on fetal outcomes or neurodevelopment. Additionally, many CBD
 products have been shown to contain varying concentrations of CBD, or are contaminated with
 synthetic cannabinoids (e.g. K2, "spice") or THC. The investigators will establish the exact
 composition of the products the pregnant women are taking in order to properly evaluate
 potential exposure levels in the developing fetus. The investigators will then correlate that
 exposure with neurodevelopmental outcomes.
Inclusion Criteria:

 -  Pregnant women

 -  Age 18 and older

 -  Must plan to give birth at UAMS

 -  Report regular (at least 3x per week) use of THC- and/or CBD-containing product
 anytime during pregnancy (for experimental groups). Women who discontinue use of
 marijuana and/or CBD during pregnancy will still be allowed in the study.

 -  Pregnant women who do not use THC or CBD will be enrolled as controls.

 Exclusion Criteria:

 -  Any other illicit drug use during pregnancy

 -  Plan to give birth anywhere other than UAMS