Cannabis as a causal factor Flashcards
What has a regular use of cannabis appeared to the double the risk of?
Developing a schizophrenic episode.
Developing long-term schizophrenia.
What does Murray’s research show in relation to cannabis and schizophrenia?
Cannabis use doubles the risk of developing the disorder later in life.
How much could the elimination of cannabis reduce the incidence of schizophrenia by?
(Murray)
8%
How many compounds in cannabis are psychoactive?
Three of the four.
What happens when cannabis is smoked in relation to its compounds?
The compounds rapidly enter the bloodstream and are transported directly to the brain.
What is the feeling of being “high” caused by?
The delta-9-THC compound binding to cannabinoid receptors in the brain.
What parts of the brain are cannabinoid receptors found in?
Parts of the brain that influence emotion, pleasure, memory, thought, concentration, sensory and time perception.
Studies show that the risk of developing schizophrenia is both age and dose-related. What does this mean?
The younger the user and the more frequent use, the higher the chance that consumption will result in schizophrenia.
What type of study was McGee et al’s? What did they study?
Longitudinal.
Cannabis use and mental health from adolescence to early adulthood.
What did McGee et al find in relation to cannabis and mental health?
Younger users are exposed to a higher than average risk.
Who did Andreasson study?
Swedish young men.
What did Andreasson suggest in relation to schizophrenia and cannabis?
The risk increases by a further 50% for those who reported using the drug more than 50 times.
What was Ashtari’s sample?
14 young adult males in residential treatment for cannabis dependence.
Patients had a history of heavy cannabis use throughout adolescence.
5 also had alcohol abuse.
14 age-matched control subjects.
What did Ashtari’s participants undergo? What were the findings?
MRI scans.
Found participants with heavy cannabis use had reduced fractional anisotropy, increased radial diffusivity and increased trace in areas known to be involved in ongoing brain development during late adolescence.
What hypothesis does Ashtari’s findings support? What is a key weakness of the study?
Heavy cannabis use during adolescence may affect normal brain maturation.
Due to concurrent alcohol consumption in 5 of the heavy cannabis use subjects, conclusions from this study should be considered preliminary.
What is a key weakness of research into the link between cannabis and schizophrenia in relation to cause-and-effect?
Since research into the link between cannabis and schizophrenia is not experimental, a cause-and-effect link cannot be established.
People with early schizophrenic symptoms may take cannabis as a form of self-therapy to deal with these negative experiences, suggesting that cannabis may be an effect of schizophrenia.
What did Caspi et al suggest?
Not everyone who uses cannabis, even at a young age, develops schizophrenia.
The increased risk might occur only in those who have a particular genetic predisposition.
