Lecture 35: Addiction Flashcards
what is a drug?
WHO definition of drug:
- a chemical entity used non-medically, self-administered for its psychoactive effect
what are some examples of drugs?
- CNS depressants: alcohol, benzodiazepines and barbiturates
- CNS stimulants: smphetamines, MDMA, BZP
- Opiods: oxycodone, morphine, codeine, methadone, homebake
- Hallucinogens: LSD, psiloycybin, ketamine
- cannabinods
- solvents
- others: steroids, nicotine, caffeine, anticholinergics, antihistamines etc
define tolerance?
- reduction in response to a drug after repeated administration
- due to receptor/second messenger desensitisation/downregulation
- acute vs chronic tolerance
- may lead to increaed intake to get desired effects
define dependence?
- compulsive drug-taking behaviour; loss of ability to control use; intrusion into normal activities; + tolerance + withdrawal
define withdrawal?
- rebound physiological effects upon cessation or reduction of drug intake
- symptoms usually opposite to those produced by drug (e.g. insomnia, anxiety - BDZs, alcohol; sedation, depression - cocaine)
what factors are associated with substance dependence?
- environmental factors
- host factors
- drug factors
what are environmental factors associated with substance abuse?
- family or peer group behaviour
- availability of other reinforcers (e.g. recreational resources)
- job/educational opportunities
- conditioned stimuli (environmental cues paired with drug use)
what are host factors associated with substance dependence?
Gene:
- positive and negative for alcohol (defective ALDH genes in Asians; reduced sensitivity to alcohol phenotype in alcoholics);
- opiod dependence associated with 2 sites of chromosome 17
what is used to predict teenage binge drinking?
the prediction model
- prediction of binge drinking based on data from a longitudinal study (IMAGEN) in 692 adolescents
- main model components:
History (romantic, sexual relationship, smoking, prior deviant behaviour etc)
Personality (extravagence, excitability, disorganisation)
Brain (pharenchymal (grey matter) volume) - the odds of adult alcohol dependence are reduced by 10% for each year drinking onset is delayed in adolescence
what are drug factors associated with substance dependence?
- ease of drug availability, price, purity and potency
- how it is administered (GI, intranasal, IV, inhalation)
- pharmacokinetic profile (speed of onset and offset of effects)
diagram: IV dosing, smoking and snorting is rapidly aborbed and high climax with intense eurphoria and psychological effects, while oral dosing (e.g. methadone) is slowly absorbed with lower climax with lower intensity psychological effects
what is the pharmalogical mechanism for drugs of abuse/dependence?
why do some drugs feel better than others?
dopamine release in the nucleus accubens
dependence-inducing drugs have many different pharmacologies
e.g. alcohol - GABA-A;GIRKS, Opioids - µ-opioid receptors, Nicotine - α4β2-nicotinic cholingeric receptors, Cocaine - DA transporter etc
BUT all release dopamine in the nucleus accumbens
associated with positive, rewarding and euphoric feelings
is it possible to treat addiction by blocking central reward pathways?
- a study done on 11 cocaine-dependent subjects
- rising, single dose, placebo insertion design. Placebo and 3 ecopipam doses (10,25 and 100mg) given.
- cocaine 30mg IV given 2h after ecopipam/placebo dosing.
- cocaine subjective effects measured by visual analog scales; also blood pressure and heart rate
results:
- 10mg didn’t have much of an effect
- 100mg blocked 80-90% of dopamine receptors
After 5-10 mins of the placebo, participants reported feeling high. wears off after 30mins
Ecopipam produced dose-dependent reductions in subjective effects of cocaine. CV effects of cocaine (BP,HR) were not affected
but chronic dosinhg = rapid tolerance occurs to antagonist effects
so only a single dose of ecopipam can treat addiction :(
how is a substance use disorder determined?
(DSM-V)
11 criteria covering 4 areas, over 12 months
2-3 months criteria = mild substance use disorder,
4-5months = moderate substance use disorder
≥6 months = severe
- *1. Impaired control**
1. taking more or for longer than intended
2. unsuccessful efforts to stop or cut down use
3. spending a great deal of time obtaining, using, or recovering from use
4. craving for substance - *2. Social Impairment**
5. failure to fulfil major obligations due to use
6. continued use despite problems caused or exacerbated by use
7. important activities given up or reduced because of substance abuse - *3. Risky use**
8. recurrent use in hazardous situations
9. continued use despite physical or psychological problems that are caused or exacerbated by substance use - *4. Pharmacologic dependence**
10. tolerance to effects of the substance
11. withdrawal symptoms when not using or using less
what are the trends of using substances globally?
- according to WHO (and despite war on drugs)
- increase use of illicit substances
- lower age of initiation
- growth in world supply
- use of multiple substances
- increasing levels of intoxication, alcoholic poisoning and drug ODs
- increased use by women
how are the prevalence rates of drugs used in NZ?
Community Samples
- Adolescent Health Research Group (2003)
- Illicit Drug Monitoring System (IDMS) - Massey U
Longitudinal Research
- Christchurch Health and Development Study
- Dunedin Multidisciplinary Health and Development Study
Clinical Samples
what does this show?
12 month prevalence data - NZ Mental Health Survey 2006
- most overrepresented are young adults 16-24 year olds (7.1% alcohol abuse, 3% alcohol dependence, 3.8% drug abuse, 2.1% drug dependence)
- with age, the prevalence of drug and alcohol use decreases
males are more affected than females
what does this show?
IDMS (illicit drug monitoring system) overview of trends in drug use in the past six months for 2014 in NZ
some drugs are easy to access, some prices are decreasing or stable, number of users in increasing,
what does this show?
ease and time taken to buy methamphetamine and cannabis in NZ
each province found it was easier to buy methamphetamine than cannabis
what are the harms of large alcohol consumption?
what are the harms of small to moderate consumption?
what are the effects linked with small and large consumption?
what were the findings of the alcohol and harm in NZ study?
- Males were ~twice as likely than females to have a heavy drinking episode, report any harm and any trouble
- Higher reports of heavy drinking episode, any harm and any trouble in young adults which decreases with age
- lowest rates in asian ethnicites, highest rates in maori ethnicities, and european ethnicities in the middle
what were the findings of the relative harm assessment?
- alcohol is most harmful for others, and 4th harmful for users
- cannabis is quite low harm for others and users
what does this show?
this is a bar graph form of the previous graph.
- alcohol was most harmful overall
- heroin and crack were next
- tobacco and cannabis were roughly the same harm overall (26 and 20)
how much regulation is needed for alcohol?
a middle ground needs to be found between excessive commercialisation of alcohol and prohibition of alcohol
what is the relationship between price and how much alcohol is consumed?
data from london
Price of alcohol has gone down and consumption has gone up!
does altering the price and availability of alcohol affect the consumption and harm of it?
Denmark increased tax, had -76% consumption, DTs cases -93% and alcohol deaths -83%
Russia reduced availability, -34% consumption, alcohol deaths -54%
Sweden had abolition of alcohol rationing (easier to access), +25% consumption, +438% DTs cases
Finland made beer available in grocery stores (20x availability), +46% consumption, alcohol deaths +58%
these trends show that limiting access decreases consumption and harm
what is the future like for addiction?
- local research
- abnormal salience (craving) for alcohol via increased anterior cingulate activity
- stimulation via implane associated with reduced craving and alcohol consumption
- an electrode is placed between 2 halves of the brain which sends electrical burst signals and the correct frequency can shut off that craving.
- graph shows: People who were taking 25 standard drinks per day on baseline, went to 0-5 standard drinks after 4-24 weeks.
