Evaluation of Cannabis influence on brain chemistry

What is the strength of determinism?

There is a biological component to cannabis causing schizophrenia Val/Val variant of COMT, therefore reducing stigma. Establishes clear cause and effect schizophrenia does not make you take cannabis

What percentage of society is prone to psychotic reactions?

25% after taking regular cannabis (Caspi et al 2005)

What evidence shows biological determinism?

COMT gene causes a susceptibility for schizophrenia alongside cannabis aswell as Val/Val variant being even more prone to psychosis

What is the weakness of determinism?

There is an element of free will as people choose to take cannabis which could result in schizophrenia.

What evidence shows free will?

Di Forti (2009) found that smoking higher potency cannabis leads to an increase in the risk of developing psychosis

Why is this explanation interactionist?

It is in between determinism (biological reasons such as COMT and Val/Val variant) as well as free will (consumption fo cannabis) the onset of SCZ symptoms are a result of the interaction between both factors.

What is the strength of Nurture?

Environmental impact suggests cannabis is a modifiable risk factor, this research allows for their to be a preventative value such as decreasing cannabis consumption to adolescents

What evidence shows nurtures impact on cannabis and SCZ?

Malone and Taylor (2006) showed that THC worsens disruptions in social behaviour caused by isolation rearing but had no effect on rats that were not socially isolated.

What evidence supports nature and nurture?

Murray (2005) argues cannabis consumption interacts with genetic susceptibility to schizophrenia.

What is a weakness of nurture?

Not everyone who uses cannabis develops schizophrenia suggesting there is a biological impact

What hypothesis supports nature and nurture?

Two hit hypothesis, a combination of neonatal prefrontal cortical lesion with chronic pubertal cannabinoid administration led to greater impairments in various forms of social behaviour (Schneider 2007)