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

Abstract

Cannabis sativa preparations are among the illicit drugs most commonly used by young people, including pregnant women. The endocannabinoid (eCB) system, which is involved in the regulation of emotional and motivational homeostasis, synaptic plasticity and cognitive functions, also plays a critical role in diverse phases of brain development. Both perinatal and periadolescent periods are critical for brain eCB system development. Thus, interference of endocannabinoid signalling by cannabis exposure may contribute to explain the enduring negative impact of cannabis on neurodevelopmental processes and the resulting psycho-physio-pathological consequences. In the present chapter we describe and discuss published data dealing with the long-term neurobehavioural effects of cannabis exposure during the prenatal and adolescent periods. Human studies have demonstrated that marijuana consumption by pregnant women critically affects the neurobehavioural development of their children. Investigations using animal models provide useful information for a better understanding of the long-lasting deleterious consequences of cannabis exposure during pregnancy and lactation. Increasing use of cannabis among adolescents is a matter of great public concern that has led to a parallel increase in research on appropriate animal models. Chronic administration of cannabinoid agonists during the periadolescent period causes persistent behavioural alterations related to cognitive deficits, increased risk of psychosis, mood disorders and addiction to cannabis and other drugs of abuse. The underlying mechanisms by which cannabis use may lead to these disorders, including genetic vulnerability and the increasing content of the main psychoactive ingredient in cannabis preparations, delta-9-tetrahydrocannabinol (THC), will be discussed. To conclude, prevention and therapeutic strategies based on scientific knowledge will be proposed.