Cannabis & Psychosis: Looking at

Transcription

1 Slide 1 Cannabis & Psychosis: Fiona Barber Justin Loach & Dr Steve Wright Slide 2 Looking at Psychosis What is it? What causes it? Cannabis What is it? What does it do? Why do people use it? What is the relationship between the two? What is the significance of the relationship? Slide 3 What is psychosis? simply indicates the presence of hallucinations, delusions, or a limited number of severe abnormalities of behaviour (WHO 1992) fundamental & characteristic distortions of thinking & perception, and emotions that are inappropriate or blunted... intellectual capacity is usually maintained (ICD-10)

2 Slide 4 What is Psychosis? Hearing voices that no one else hears or seeing things that aren t t there Believing that others can influence their thoughts, or that they can influence the thoughts of others Believing that they are being watched, followed or persecuted by others Feeling that their thoughts have sped up or slowed down Thinking in a confused way Slide 5 Stress-Vulnerability Model Risk Factors genetic susceptibility / family history brain damage / trauma developmental factors / life events beliefs / low self-esteem esteem social factors Critical Incident Acute stress / Trauma Substance Misuse Psychosis Slide 6

3 Slide 7 Slide 8 What is in it? Over 60 Cannabinoids (unique to plant) The major active constituent is: 9 tetrahydrocannabinol (THC) Mimics natural endocannabinoids Slide 9 How is it taken? Smoke inhalation - Joint - Pipe - Water Pipe or Bong - Vaporiser Oral (raw or as cooking ingredient) Unsuitable for intravenous use (fat soluble)

4 Slide 10 Dosage THC levels vary widely according to plant characteristics and the part of the plant Concentration of THC varies from 2% (low- grade resin) to 20% (skunk) and up to 50% (oil) Slide 11 What does it do? Slide 12 Acute effects (Iversen Iversen,, 2000) An initial buzz with lightheadedness Euphoria and fatuous laughter An enhanced sensitivity of perception Enhanced appreciation of art and music Hallucinations, usually transient & ill formed Fantasies, often of a grandiose nature Disordered time perception Slide 13

5 Negative experiences Panics (22%) Paranoia (15%) Impaired memory Tiredness Low energy Depression (Thomas 1996, Reilly 1998, Atha 1997) Slide 14 How does it work? Slide 15

6 Slide 16 Why do people choose to take cannabis? Reasons for cannabis use in men with and without psychosis BOB GREEN, DAVID J. KAVANAGH & ROSS MCD YOUNG Drug and Alcohol Review (December 2004), 23, Slide 17 Self-reported positive effects Effect Relaxation Mood alteration Cognitive effects Interaction Entertainment Perceptual change Psychotic symptoms Psychosis 27% 42% 20% 20% 13% 13% 2% Control 53% 34% 32% 26% 19% 2% 2% Slide 18 Self-reported negative effects Negative effect Psychotic symptoms* Physical effects Decreased energy Impaired cognition Neg mood change Lack of cannabis! psychosis 24% 7% 4% 2% 9% 9% controls 9% 17% 13% 11% 6% 0% *especially paranoid

7 Slide 19 Summary of Motives 1) Enhancement (to get high, feel good, fun) 2) Social Motive (positive) 3) Coping with unpleasant affect (depressed, worried, nervous, bored, restless etc.) 4) Conformity & acceptance 5) Relief of positive symptoms & side-effects effects (Spencer et al 2002) Slide 20 Slide 21 In what ways might it be helpful? Anti-emetic e.g. for chemotherapy (nabilone) HIV-related wasting Glaucoma Multiple sclerosis Muscle spasticity Movement disorders Asthma Painkiller (e.g. terminal care)

8 Slide 22 Slide 23 How does cannabis affect the course of schizophrenia and related psychoses? Cannabis is an independent risk factor for: - more psychotic relapses - aggravation of psychotic and disorganization symptoms Shows a dose dependent relationship Not explained by differences in medication use Some reduction of negative symptoms and anxiety/depression with mild abuse (Linszen & 2004, Van Os+ 2002, Peralta & Cuesta 1992, Dixon+ 1991) Slide 24 What is the evidence that cannabis causes psychosis or schizophrenia? Rates of cannabis use are higher among people with schizophrenia than general pop. 3 population-based studies assessing cannabis use in adolescence 50,087 swedish conscripts (Andreassen( Andreassen,, 87) Dutch NEMESIS sample (Van Os, 2002) Dunedin birth cohort (Arsenault, 2002) Dose dependant effects

9 Slide 25 Slide 26 Summary Cannabis is widely used and abused There chemical content varies and there is a poor understanding of their effects There is clear evidence of harmful effects of cannabis on health and in established psychosis but less evidence about possible benefits It significantly increases the risk of psychosis particularly if used in early life by highly vulnerable subgroups If cannabis did not exist, the incidence of schizophrenia might be reduced by about 10% Slide 27 Addressing cannabis use in those with psychosis Address current circumstances and extent of use Look at history of use & past treatment Consider what impact current use has on illness Discuss motives for ongoing use Readiness to change? Realistic goals? Support (stop, use less or harm reduction)

10 Slide 28 And everyone else? Provide clear unbiased information about the risks of cannabis use to: Adolescents (early in secondary education) Parents Teachers, youth workers, health workers etc. Encourage further research Provide guidance and support for people to help them to address their cannabis misuse