Lecture 7 - Alcohol 1 Flashcards
What is the relevance of alcohol to the individual and society?
- Alcohol has been a part of society for a long time (9000 years+)
- Alcohol a part of social life in many countries
How are drug harm scales developed?
- Development of drug harm scale:
- Experts assign score (0-3) for each parameter
- Parameters are averaged to yield overall harm score
- Nutt et al. (2007)
What is the claim that alcohol is ‘more harmful than heroin or crack’ based on?
- Lancet study
- Based on an expert assessment of drug harms to users and others (i.e. society)
Where does alcohol lie on the drug harm scale?
5th - between street methadone and ketamine
How have harms associated with drugs achieved improved criteria and weighting?
- 16 criteria (9 in 2007 study)
- Scores from 0-100 (0-3 in 2007 study)
- Differential weighting of criteria to indicate their different importance
Is alcohol more harmful to users or others?
Others
What are ‘dirty drugs’?
Nonspecific effects – not as targeted effects as other drugs
What are nonspecific effects?
Interactions with lipid bilayer; mainly at higher concentrations
What are specific effects?
Interaction with ligand-gated ion channels (i.e. neurotransmitter receptors) and voltage-gated ion channels; at concentrations within range achieved by common alcohol consumption
How does alcohol take a first hit on specific neurotransmitter systems?
- Alcohol takes a first hit on specific neurotransmitter systems
- Neurotransmitter receptors (NMDA, GABA-A, Glycine, 5-HT3, nAch)
- Voltage-gated ion channels (L-type Ca2+ channels, GIRKs)
- -> cascade of synaptic events involving neurotransmitters
- Overall, acute alcohol tends to dampen neural activity (e.g. stimulation of inhibitory GABA receptors)
White (2003) quote about alcohol
“If recreational drugs were tools, alcohol would be a sledgehammer. Few cognitive functions or behaviours escape the impact of alcohol” – White (2003)
What are some acute psychological effects of alcohol?
- Decreased tension/anxiety (anxiolysis)
- Impaired memory (amnesia, ‘black out’)
- Directly ‘rewarding’ effects of alcohol?
What are the variables affecting the effects of ethanol in humans?
- Psychological effects of alcohol depend on complex interactions between many variables
- Environmental variables (social cues)
- Cognitive Set (expectancy)
- Mood, arousal, personality factors
- Age and sex of subjects
- Exposure to other drugs (coffee, nicotine etc.) and nutritional state of the subjects
- Variables related to ethanol ingestion = dose, rate of ingestion, time of testing post ingestion/time of day, type of beverage ingested (role of congeners)
What has been shown about alcohol-induced reduction in tension and anxiety?
- View that alcohol reduces tension and anxiety – and that this effect is a major contributor to alcohol consumption and abuse – is widely held, even though studies on human subjects have reported variable effects on measures of anxiety (e.g., self report, autonomic arousal) (Wilson, 1988; Kushner et al., 2000)
- Similar to classical anxiolytics, such as benzodiazepines, alcohol acts as indirect agonist at GABA-A receptors, i.e. enhances the response of the major inhibitory neurotransmitter GABA (Harris & Mihic, 2004)
- Commorbidity of anxiety disorders and alcohol abuse (Kushner et al., 2000)
- Alcohol relatively consistently reduces measures of anxiety in rodents (e.g., Blanchard et al., 1993)
What did the study by Gallate et al. (2003) show about how beer drinking in rats reduces anxiety?
- Cat odour avoidance test = cat odour in a box which rats have an innate anxiety of, so they don’t approach and stay behind the wall. If anxiety is reduced (through alcohol – higher alcoholic beer), they approached the cat odour more readily/hid less
- Elevated plus maze test = rats naturally don’t like heights and open spaces, so a normal rat won’t stick their head out of an elevated plus maze. Measure reduction in anxiety by how much they venture into open areas (greater with higher concentrations of alcohol)
- Gallate et al. (2003)
What did the study by Spanagel et al. (1995) show about how anxiety predicts ethanol self-administration in rats?
- Split animals into anxious and non-anxious rats (based on elevated plus maze behaviour)
- Then given opportunity to self-administer alcoholic drinks
- Higher alcohol self-administration in anxious rats
- Spanagel et al. (1995)
- Suggests anxiety is a predisposing factor contributing to alcohol consumption
What are the physiological effects of chronic (excessive) alcohol consumption?
- Neuropharmacological adaptations, withdrawal symptoms and alcohol dependence
- Severe and chronic cognitive deficits due to brain shrinkage (Wernicke-Korsakoff Syndrome)
