Presentation is loading. Please wait.

Presentation is loading. Please wait.

CANNABIS II & CAFFEINE C81ADD – The Psychology of Addiction Dr. Mark Haselgrove.

Similar presentations

Presentation on theme: "CANNABIS II & CAFFEINE C81ADD – The Psychology of Addiction Dr. Mark Haselgrove."— Presentation transcript:

1 CANNABIS II & CAFFEINE C81ADD – The Psychology of Addiction Dr. Mark Haselgrove

2 Overview of the lecture (1) Cannabis Abuse, and chronic exposure effects Tolerance & Dependence Adverse behavioural and health effects (2) Clinical applications of Cannabis Analgesia Anti-emetic (3) Caffeine Background & Pharmacology Behavioural effects Tolerance & Dependence

3 Brooks et al (1999) Longitudinal study of 776 ss from New York state. Marijuana: A gateway to harder drugs….? Age of initiation… Most widely used illicit drug in UK and US (4.6 %, 14 Million in US) - Difficult to asses, perhaps some users are more disposed to try harder drugs Progression from initial to regular user… Gruber & Pope (2002) Risk factors: Family disturbances, drug use by family/peers, School performance, age of onset

4 Tolerance & Dependence With repeat use, does tolerance develop? Mixed result in human studies: (1)Compton et al. (1990) – Tolerance observed following repeated administration of marijuana or pure THC. (2) Kirk & de Wit (1999), Lindgren et al (1981) – Same high in light/infrequent users relative to heavy/frequent users

5 Tolerance & Dependence With repeat use, does tolerance develop? Animal studies more consistent Breivogel et al (1999): rats Daily injections of THC (10 mg/kg) over 3 weeks Progressive reduction in: - CB1 receptor density -Cannabis agonist receptor activity. -Some brain areas totally desensitized in 3 weeks.

6 Tolerance & Dependence Dependence:(1) Difficulty stopping taking Cannabis (2) Craving for cannabis (3) Withdrawal symptoms A number of studies report that abstinence triggers: - irritability, anxiety, depression, sleep disturbance, aggressiveness, - decreased appetite (e.g. Budney et al., 2003; Kouri et al.,1999) Resemble nicotine withdrawal symptoms Worst in first 2 weeks – can for last over a month

7 Tolerance & Dependence Animal Studies: - Early studies found no effect of drug withdrawal. - But THC has a long half life. Thus still present in system… Precipitated withdrawal (e.g. Aceto et al., 1996): Rats given twice daily THC injections Then given SR (CB1 receptor antagonist) Rats displayed: symptons of hyperactivity (shaking, face rubbing, scratching) Possibly a consequence of rats being stressed: de Fonseca (1997) - Corticotrophin–releasing hormone (CRH) in precipitated withdrawal rats

8 Tolerance & Dependence Treatment Cognitive- behavioural therapy Participants rewarded with vouchers for providing cannabis- free urine samples Significant relapse though: Moore & Budney (2003) Haney et al., 2004: Withdrawal symptoms may be eased by oral consumption of THC Useful in the short-term, difficult to achieve long-term abstinence.

9 Behavioural and health effects (1) Psychological effects Lynsky & Hall (2000) – chronic cannabis use education performance Greater cannabis use: More negative attitudes about school Poorer grades Increased absenteeism Is this just a correlation or causation? Lynsky & Hall (2000) - Amotivational syndrome: apathy; aimlessness; lack of productivity, long term planning and motivation

10 Behavioural and health effects (1) Psychological effects Solowij et al. (2002) – Cognitive deficits in long term users Standardised tests of learning, memory and attention: long-term users deficient 1 and 7 days after exposure Pope et al. (2001) – no difference between heavy users and controls after 28 days Cognitive deficits linked to recent use – reversible over time. Fergusson et al., (2003) Regular cannabis use early in life predicts poor school performance and drop-out rates Matter for debate – Hot topic…

11 Behavioural and health effects (2) Health effects First, the good news… No one reported to have died from Cannabis overdose BUT, (1)Higher concentrations of carcinogens in cannabis smoke than tobacco More tar and carbon monoxide/ joint than a cigarette (2) Cannabinoids affect the immune system: Cabreal & Pettit (1998): THC suppresses immune function, increase risk of viral and bacterial infection (3) Cannabinoids affects reproductive function: Smoking in women suppresses luteinizing hormone release (but can be tolerated) Smith & Asch (1987) - sperm count in men (but only in heavy users)

12 Clinical applications - Can be tracked back hundreds/thousands of years - Late C19 and early C20: crude extracts used in US and European treatments Identification of THC manufacture of synthetic compounds Dronabinol Nabilone Antiemetic for chemotherapy patients Appetite stimulant on AIDS patients Anecdotal evidence/limited clinical studies: Cannabis also used for treatment of chronic pain:Multiple sclerosis Spinal cord injury Glaucoma Limited widespread use (especially in US) – (1) Side effects (2) Joints more effective than synthetics BUT, HU-211, a cannabinoid that doesnt activate CB1 receptors – no side effects Undergoing clinical trials


14 Caffeine – Background & Pharmacology - Major source of caffeine = Coffee and Tea % of people regular drink. - Average (adult) daily intake = mg - Consumption in children through chocolate & soft drinks

15 Caffeine – Background & Pharmacology -Caffeine absorbed through the gastrointestinal tract (in about min) -Plasma half life of around 4 hours, but usually topped up People have a rising concentration in blood plasma throughout day -Caffeine converted to metabolites by the liver -95% excreted in urine, 2 - 5% in faeces, rest through saliva

16 Behavioural Effects Caffeine has a biphasic effect:Low dose- Stimulant, locomotor activity High dose – Reversed, activity More than just an arouser: Smith et al., (1999) Low- intermediate doses = variety of positive subjective effect - SS instructed to abstain from coffee, tea etc - Beverage containing 40 mg caffeine Could these positive effects be an alleviation of withdrawal symptoms? Rogers & Dernoncourt (1998)

17 Behavioural Effects Tolerance & Dependence Griffiths & Mumford (1995) Tolerance to subjective effects of caffeine e.g. heavy drinkers can consume coffee before bed. Abstinence Withdrawal symptoms Griffiths et al. (1990): Withdrawal in (at least)100mg/day drinkers (1 cup a day) Health effects (Chronic consumption): (1) blood pressure (2) coronary heart disease (3) infant birth weight

18 Reading Meyer, J. S., & Quenzer, L. F. (2005). Psychopharmacology: Drugs, the brain and behavior. Sinauer. Chapter 13 & 12

Download ppt "CANNABIS II & CAFFEINE C81ADD – The Psychology of Addiction Dr. Mark Haselgrove."

Similar presentations

Ads by Google