Concepts of cannabis influence on brain chemistry

What is a critical phase of brain development? What characterises it?

Adolescence, characterised by neuronal maturation and rearrangement processes

What system plays an important role in fundamental brain development?

The endocannabinoid system

What psychoactive compound can change neurobiological functions and behaviour?

THC

Singh and Balhara 2017

A review of Indiana research on co-occurring cannabis use disorders and psychiatric disorders found that younger and more frequent users are at a higher risk of developing cognitive decline

Hanna et al (2016)

Evidence from brain scans shows more significant brain matter loss in first episode schizophrenia patients with a history of cannabis use.

Murray (2005)

Argues cannabis consumption interacts with genetic susceptibility to SCZ between the COMT gene and cannabis consumption, people with the Val/Val variant of COMT are more likely to develop psychosis after cannabis abuse in adolescence.

Caspi et al (2005)

The majority of the population can abuse cannabis but a vulnerable minority (25%) is prone to psychosis

Malone (2010)

The brain mechanisms of adolescent exposure to cannabis to increase the probability of SCZ is still unsure

What does the CB1 presynaptic cannabinoid receptor do?

Activation inhibits neurotransmitter release from the axon terminal

Rubino et al (2008)

Adolescent cannabinoid exposure produces a long lasting decrease in CB1 receptors expression in specific brain areas

Gardner (2005)

Cannabis causes an increase in extracellular dopamine, psychosis results from aberrant salience caused by disordered dopamine transmission

Bayer et al (1991)

Cannabis risk factor is more consistent with two hit hypothesis, genetic or pre/post-natal developmental predisposer (first hit) combines with environmental hazard e.g cannabis exposure (second hit) which leads to psychosis