1. 1 Gene Environment Interaction THC THC THC COMT Pre-adolescence period
Cannabis and Psychosis: Transition to Psychosis
Amresh Shrivastava, MD,DPM,MRCPsych.FRCPC, Johnston M Ph.D, Terpstra K, MA.Bureau Y Ph.D.
Associate Professor of Psychiatry Western University, London, Ontario, Canada ,
Clinical Syndromes
Psychotic disorder
Schizophrenia spectrum
Substance abuse psychosis
Psychosis NOS
ARMS
Psychosis/schizophrenia
Affective disorder
Anxiety disorder/ other disorders
-1200 BC
Indus Valley- five sacred plants
1894
No evidence of mental or moral injuries
1928
Recreational use banned in UK
1942
Removed from American pharmacopeia
1961
60 Nations signed ‘end cannabis in 25 years
1985
THC isolated
1970
Clear evidence of psychological effect
1987
First evidence of link with schizophrenia
1988
CB receptors discovered by Hewlett & Devane
1992
First Endocannabinoid discovered
2000
Agonist shown to reduce plasticity
2002
Effect on long term plasticity
2005
Cannabis based medicine for MS in Canada
No vulnerability (1)
Biological vulnerability
Genetic studies (2)
Cannabis induced neurobiological changes
Seen in neurochemical and neuroimaging (3)
Cognitive dysfunction(4)
Seen in memory, executive function, information processing
Cognitive dysmetria (4)
Excessive THC
Psychosocial stress
& environmental event
External biological events (5)
Abstract: Abbreviated: Trajectory
Gene Environment Interaction 1
Neurochemical Outcome
Dopamine
Serotonine
Psychosocial
unmasking
Environmental Unmasking
Biological
Unmasking
Genotype
Behavioral traits-correlates
Life style factors
Risk factors
Brain vulnerability
Essential etiological factors 1
Family History
Conclusion
there is robust and consistent association between cannabis consumption
Cannabis supposedly cases almost similar neurobiological changes as seen in schizophrenia
Association of cannabis , psychosis in Normal individual and cannabis use in Schizophrenia is not clearly known
cannabis does not cause any structural changes per say.
the alleged role played by the endocannabinoid system in later developmental phases such as the adolescent one, prompted speculation that alterations in the endocannabinoid tone
Although the direct pathway of causation from cannabis consumption to development for psychosis is not known, pharmacological as well as behavioral studies intend to develop better intervention and prevention of psychosis which remains critical.
Biological
Endophenotype
Gene
PFC
Amygdala
Brain Maturation
CB Receptor
Cannabinoids
Brain Changes
Executive function
Information processing
Cognitive dyscontrol
Dopamine
5 HT
Behavioral Changes 2
THC
THC
THC
COMT
Pre-adolescence period
Adolescence
Post adolesence 3
Possible trajectory of Cannabis and related Psychosis
ARMS – At risk mental state, THC – Tetrahydro cannabidole,PFC – Prefrontal cortex, COMT – Catechol-o-methyl transferase, 1,2 and 3- different levels biological events
Published: Shrivastava A. Johnston M, Terpstra K, Bureau Y.Pathways to Psychosis in Cannabis  Abuse.Clin Schizophr Relat Psychoses Mar 14:1-18. [Epub ahead of print]
Shrivastava A. Johnston M, Tsuang M Cannabis use and cognitive dysfunction..Indian J Psychiatry Jul;53(3): doi: /