Psych 3822 Chapter 9: Alcohol

Where does alcohol rank among the most commonly used drugs in the world?

It is the second most commonly used drug in the world

What is the most commonly used drug in the world?

Caffeine

Ethyl alcohol

AKA ethanol. The only type of alcohol fit for human consumption

Is isopropyl safe for consumption?

No

Is methyl alcohol/methanol safe for consumption?

No

Is ethyl alcohol/ethanol safe for consumption?

Yes

Which Canadian province has the highest prevalence of alcohol use?

Quebec

Percentage alcohol

(Or alcohol by volume) refers to the amount of alcohol in grams per 100 milliliters of solution (e.g., 15g in 100ml= 15%)

1 gram = ___ milligrams?

1000

Proof of alcohol

A number that is 2 times the percentage of alcohol (e.g., 50% = 100 proof)

Standard drink

Contains 14 grams of (100%) alcohol. Because different beverages have different alcohol concentrations, the actual liquid volume needed to equal one standard drink changes:

e.g., 5 ounces of wine (12% alcohol), 12 ounces of beer (4.5% alcohol)

Alcohol density

798.9g/l

Fermentation

Alcohol is produced through this process: product of yeast consuming starches and sugars in grains or fruits.

Upper limit for percentage alcohol produced through fermentation

15%

Beer fermentation yields up to what % alcohol?

Fermentation of grains yields up to 5% alcohol

Wine fermentation yields up to what % alcohol?

Fermentation of fruits produces 12-15% alcohol

Distillation

Process that increases the percentage of alcohol in a solution by heating then condensing vapour.

Used to make alcoholic beverages with much higher concentrations of alcohol (e.g., "spirits" like rum, vodka, etc)

Upper limit for percentage alcohol produced through distillation

Up to 95% alcohol is possible

What method of production would you use to make spirits (e.g. rum, vodka, etc)

Distillation is used to make alcoholic beverages with much higher concentrations of alcohol

Alcohol prohibition in the US

1920: The 18th amendment prohibited the sale and distribution of alcohol

1933: The 21st amendment repealed the 18th amendment, so they could sale and distribute alcohol again

What % of Canadians drink alcohol

~80%

How many Canadians are born with fetal alcohol spectrum disorder (FASD) each year?

3000

How many Canadians risk acute illness because of alcohol?

3 million

How many Canadians risk chronic conditions (e.g., liver disease, cancer) because of alcohol?

4.5 million

How does the solubility of ethanol impact its absorption

It is both water and lipid soluble, so it is easily absorbed

How to increase the speed of alcohol absorption

Quicker absorption on an empty stomach. Carbonated drinks increase speed of absorption

How is alcohol administered?

Orally in the form of beverages

Where does alcohol enter the bloodstream?

In the GI tract (mostly the small intestine)

How does alcohol consumption impact thiamine?

Alcohol impairs the thiamine (Vitamin B1) transporter in the upper GI, which can create thiamine deficiencies in the body and brain

What condition results from thiamine (vitamin B1) deficiencies?

Wernicke-Korsakoff Syndrome

Blood-alcohol concentration (BAC)

Grams of alcohol per 100 mL of blood

Why is BAC used?

BACs are often used to categorize the types of effects the user experiences and is often used for legal definitions of intoxication

*When does BAC peak?

Maximum BAC from an alcoholic drink occurs after ~45 min

*Legal BAC limit for driving in Canada?

0.08 (for a fully licensed driver with no convictions)

BAC produced by 1-2 drinks

0.04

Where in the body is alcohol metabolized?

Metabolism occurs in stomach and liver (mostly), but also other parts of the body

Metabolism of alcohol

Alcohol -(broken down by alcohol dehydrogenase)->

Acetaldehyde -(broken down by aldehyde dehydrogenase)->

Acetic acid or acetate, which can then be excreted through urine, sweat, or breath (water, carbon dioxide)

*Alcohol dehydrogenase

Breaks down 95% of alcohol into acetaldehyde

*Acetaldehyde

Alcohol is broken down into this compound, which causes aversive effects, such as nausea. It is then broken down into neutral acids to be excreted

*Aldehyde dehydrogenase

Breaks down acetaldehyde (the compound alcohol is broken down into) into acetic acid and acetate, which can then be excreted through urine and breathing

What would happen if you injected someone with acetaldehyde

They would feel the aversive, noxious effects, such as nausea and vomiting

How does metabolism of alcohol in the stomach differ between men and women

Alcohol metabolism in the stomach occurs 20% less in women

Flushing of the face when drinking

Due to histamine release from exposure to acetaldehyde (like an allergy). ~50% of people of Asian descent experience this

How does pharmacokinetic tolerance impact the metabolism of alcohol?

95% of alcohol is broken down by alcohol dehydrogenase, but some of it is metabolized by another enzyme, CYP2E1 (I don't think we need to know the enzyme name).

For infrequent drinkers, this enzyme accounts for very little metabolism, but it metabolizes much more alcohol in chronic, heavy drinkers.

*How does increased alcohol dehydrogenase affect the rate of alcohol metabolism?

Alcohol is converted to acetaldehyde more quickly, greater accumulation/build up of acetaldehyde. You're more likely to experience the negative effects of alcohol

*How does decreased aldehyde dehydrogenase affect the rate of alcohol metabolism?

Slower breakdown of acetaldehyde, therefore, a greater accumulation of acetaldehyde. A lot of people have this polymorphism and it causes things like flushing of the face

What rate of elimination does alcohol follow?

Zero-order kinetics, eliminated at a fixed amount per hour (avg 7g per hour)

Are there times when alcohol elimination does not follow zero-order kinetics?

At low amounts, if enzymes are not saturated, first-order kinetics may apply

How much alcohol is eliminated per hour

On average, 7g of alcohol per hour. About ½ a standard drink per hour (2 hours per drink)

How much alcohol is eliminated through the lungs

5% of alcohol consumed

Ratio of alcohol concentration in expelled air to blood

1:2,300

Breathalyzer tests

Use this ratio (1:2,300, expelled air:blood) to accurately determine the amount of alcohol in blood

What % traffic fatalities are linked to alcohol use

30% (US stats)

*Alcohol pharmacokinetic interaction

Alcohol and acetaminophen are both broken down by enzymes in the liver, resulting in a toxic effect. Metabolism for these drugs slows down

*Alcohol pharmacodynamic interactions

When taken with depressants like benzodiazepines, barbiturates, GHB, and opioids, there is an enhanced sedative-hypnotic effect

*What drugs does alcohol interact with

Acetaminophen, benzodiazepines, barbiturates, GHB, opioids

Are heavy drinkers more likely to be male or female

More heavy drinkers are male

Are males or females more likely to be involved in an alcohol-related car crash

Males, they are also more likely to be involved in fatal alcohol-related car crashes

*How does alcohol act on GABA A receptors?

Positive modulator. Chloride ions enter the neuron, hyperpolarizing the cell, which inhibits neural activity. Alcohol increases the length of receptor activation and increases the flow of Cl- ions into the neuron. Location of receptors dictate effects. Inhibits activity in hippocampus, thalamus, and cerebral cortex for depressant effects. Exhibits rewarding effects in nucleus accumbens

When alcohol binds to GABA A receptors, is the cell hyperpolarized or depolarized?

Hyperpolarized, inhibiting neural activity

How does alcohol modulate GABA A receptors

Positive modulator

When alcohol binds to a GABA A receptor, what happens?

Chloride ions enter the neuron, hyperpolarizing the cell, which inhibits neural activity.

Alcohol increases the length of receptor activation and increases the flow of Cl- into the neuron.

When alcohol acts on GABA A receptors located on the cerebral cortex, hippocampus, and thalamus, what are the effects?

Depressing effects. Responsible for the depressant effects on cognition/memory

When alcohol acts on GABA A receptors located on the nucleus accumbens and VTA, what are the effects?

Rewarding effects. Responsible for increased dopamine associated with reward.

*Three ways that alcohol leads to increased dopamine release

1) Alcohol enhances endogenous opioids in the VTA

2) Alcohol enhances the inhibitory GABA A receptors on GABA neurons in the VTA (disinhibition)

3) Alcohol stimulates GABA A receptors on GABA neurons in the nucleus accumbens that project to the VTA and inhibit dopamine release (disinhibition)

*3 ways chronic alcohol use create tolerance to alcohol's reinforcing effects

1) Reduces the number of GABA A receptors

2) Reduced response of GABA A receptors to alcohol

3) Less release of b-endorphin, resulting in less inhibition of GABA neurons.

How does the quantity of GABA A receptors correlate with severity of alcohol withdrawal symptoms?

Reduced GABA A receptors contribute to dangerous withdrawal symptoms (less inhibition in the brain)

How does chronic alcohol use impact NMDA receptors

Leads to increased number, upregulation, of receptors

Does alcohol excite or inhibit NMDA receptors?

Inhibits

Is alcohol an agonist or antagonist for NMDA receptors?

Non-competitive antagonist

How does upregulation of NMDA receptors from chronic alcohol use impact withdrawal?

Increased NMDA receptors = more excitation (by glutamate).

*How does alcohol act on NMDA receptors?

Noncompetitive antagonist for these receptors, which counteracts excitatory effects otherwise resulting from glutamate neurotransmission. Contributes to rewarding effects in the nucleus accumbens.

Why does alcohol cause increased urination?

Alcohol suppresses the release of vasopressin in the hypothalamus AKA anti-diuretic hormone. This, alcohol leads to increased urination

Alcohol effects on behaviour and cognitive functioning

Mood changes (e.g., euphoria, reduced anxieties, reduced inhibitions).

Balance and equilibrium are affected at low doses.

Alcohol use causes poor judgement through disinhibition. A specific disinhibition trait is impulsivity.

5-2 rule

No more than 5 days of drinking in a given week, no more than 2 drinks on any day. Informally recommended rule

Alcohol priming

Refers to the tendency for individuals to feel an urge to drink more alcohol after having one of two drinks.

Can priming be a result of disinhibition?

Yes. Having the first drink leads to less inhibition of taking further drinks. That is why AA says not to take the first drink

Alcohol effects on reaction time

Alcohol decreases performance on tasks that rely on reaction time.

Alcohol effects on attention

Alcohol impairs divided attention. Light to moderate alcohol use is not associated with decreased vigilance or sustained attention.

Alcohol effects on memory

Alcohol can produce memory deficits

Tension reduction hypothesis

Suggests that habitual users of alcohol use it to reduce stress

Alcohol stupor

(or drunken stupor) can occur at BACs of 0.20 or higher.

Reversible drug-induced dementia

Occurs at BACs of 0.25 and higher and is associated with blackout.

Blackouts

Involve complete lack of memory for a period of alcohol intoxication

Fragmentary blackouts (or brownouts)

Involve incomplete memories for times of alcohol intoxication. At higher BACs, individuals tend to become unconscious. BACs of 0.25 or higher can cause alcohol poisoning.

Alcohol poisoning

Caused by BACs of 0.25 or higher

Alcohol effects on sexual behaviour

Alcohol use may enhance interest in sex but impair physiological arousal (at higher doses). Linked to risky sexual behavior (disinhibition)

Alcohol relation to crime and violence

Alcohol use is statistically related to: Homicide (alcohol involved in 34% cases). Assault, including family violence, sexual assault, and "date" rape (40% cases).

Alcohol relation to suicide

About ⅓ of suicides involve alcohol

Holiday heart syndrome

Alcoholic cardiomyopathy, and the cardiac arrhythmias that occur after a heavy drinking episode are sometimes referred to as holiday heart syndrome.

Wernicke-Korsakoff's syndrome

Long-term alcohol use causes deficiencies in vitamin B1, which can lead to Wernicke-Korsakoff's syndrome. It mainly causes vision changes, ataxia, and impaired memory

Fetal alcohol syndrome

Facial and developmental abnormalities associated with the mother's alcohol use during pregnancy (peak BAC and duration of alcohol exposure)

What amount of alcohol is considered safe to consume when pregnant?

There is no known safe amount of alcohol exposure for a developing unborn child

Acute tolerance

Refers to tolerance that onsets during a given drug taking session

Metabolic tolerance to alcohol

Involves an increase in liver enzymes that metabolize alcohol.

Pharmacodynamic tolerance to alcohol

Occurs as NMDA receptors are upregulated to offset the inhibitory effects of alcohol.

Behavioral tolerance to alcohol

Refers to reduced behavioral impairment observed in experienced drinkers.

Alcohol use generally leads to sensitization to what?

Sensitization to alcohol's reinforcing effects

Type I alcohol addiction

Occurs in older individuals who are at high psychosocial risk for addiction.

Type II alcohol addiction

Occurs in younger individuals who are at a high genetic risk for addiction.