Alcohol Flashcards
What is the compound known as drinking alcohol?
Ethanol
What is the most commonly detected and litigated drug in criminal cases?
Alcohol
Give examples of cases in which alcohol may play a role.
SA
Homicide
Assault
Impaired driving
What type of investigations does alcohol play an important role in?
Death
What units of measurement is blood alcohol concentration commonly reported in?
mg of alcohol in 100 mL of blood (mg/100 mL)
Often: 0.08g/100 ml
(numbers are just an example)
What is the legal BAC limit?
80 mg/100 mL
i.e., 0.08 g/100 mL
How does ethanol absorb?
By diffusion
What organs absorb ethanol?
25% through stomach, remainder through small intestine
What influences the rate of alcohol absorption?
Type of beverage and presence of food in stomach
How does food in stomach effect ethanol absorption?
Prolongs gastric emptying time (i.e., opening and closing of pylrous valve)
This delay will result in a lower peak BAC
Which organ primarily metabolizes alcohol?
Liver
How much of an ingested dose of alcohol is metabolized? What happens to the remaining amount?
96-98% metabolized
2-4% excreted in urine, breath and sweat
What is the primary enzyme responsible for alcohol metabolism?
Alcohol dehydrogenase
When might the rate of elimination of alcohol not remain constant?
If drinking pattern changes over long term (i.e., alcoholics)
Who are higher rates of alcohol metabolism observed in?
Chronic drinkers
What is the average elimination rate used for forensic purposes?
10-25 mg/100 mL/hour
Describe the pharmacological action of alcohol.
Simple molecule that readily crosses cell membrane including blood-brain barrier
Has specific and non-specific effects on CNS
Non-specific effects due to disturbing proteins in cell membranes
List the 3 non-specific effects of alcohol on neuronal membranes.
- Disturbs relationship of protein in membrane ‘2. Interacts with polar heads of phospholipids
- Alters lipid composition
List the 4 specific effects of alcohol on neuronal membranes.
- Acts at neurotransmitter binding site
- Modifies gating mechanism inside channel
- Interacts directly with channel protein
- Stimulates Gs, which is linked to adenylyl cyclase
What neurotransmitter systems does alcohol affect?
Virtually all
Describe the specific effects alcohol has on some neurotransmitters at lower concentration
Increases inhibitory effects of GABA receptors
Inhibits glutamate receptors
i.e., increases inhibitory transmission, decreases excitatory
Increases 5-HT neurotransmission
Stimulates DA transmission in the mesolimbic pathway
What effect does alcohol have on the CNS?
Is a CNS depressant
What is the initial effect of alcohol?
Disinhibition
What happens to the effects of alcohol as BAC increases?
Increase
Which correlates well with BAC - impairment or gross physical signs of intoxication?
Impairment
What does intoxication refer to?
Visible signs of drunkenness
What is impairment?
Relates to changes in CNS function
e.g., an increase in choice reaction time
What is often at issue at impaired driving trials?
Impairment vs. intoxication
Describe the effects of alcohol at 10-50 mg%.
Decreased inhibitions
Increased talkativeness
Euphoria
Flushing of the faceD
Describe the effects of alcohol at 50-100 mg%
Novice and light drinkers may experience signs of slurred speech and impairment of fine motor coordination
Describe the effects of alcohol at 100-200 mg%
Moderate drinkers experience slurred speech, incoordination, even simple tasks exhibit impairment
Describe the effects of alcohol at 200 to 300 mg%.
Marked loss of coordination (stumbling), mental confusion, memory loss, marked sedation, coma
Describe the effects of alcohol at >300 mg%
Attributed to acute alcohol poisoning deaths
How high have BACs been detected in drinking drivers?
In excess of 500 mg%
What leads to alcohol tolerance?
Chronic use
What is alcohol tolerance?
Involves metabolic and behavioural changes
Visible signs of intoxication are decreased
What is metabolic tolerance of alcohol?
Liver enzyme production increases
Leads to increase in elimination rates
Describe functional tolerance of alcohol.
Alcohol abusers often modify behaviour in order to mask gross signs of intoxication
List some ways in which people may mask their intoxication.
Standing/walking with wider stance accommodates stagger
Speaking slower and annunciating carefully to mask slurred speech
What are the two ways to estimate BAC?
Back projection
Forward projection
What is back projection?
Calculates from a known alcohol concentration
e.g., blood alcohol result or breath alcohol result to a previous point in time
What is required for back projection?
Elimination rate
Time of incident
What is forward projection?
Calculates forward to a specific point in time or timeframe and is based on a number of factors.
What is required for forward projection?
Elimination rate
Gender
Weight
Drinking history
Time of drinking
What evidence can be used to prove consumption of alcohol?
CCTV videos
Photos
Bar receipts
What is included in a drinking history?
Knowledge of available drinks, alcohol percentage and volume
What are the different definitions of drinking behaviour?
Social
Moderate
Heavy
What are the recommendations made by CAMH for weekly drinking?
Women - 10 drinks/week, no more than 2 per day (most days)
Men - 15 drinks/week, no more than 3 per day (most days)
How does the NIAAA define binge drinking?
Pattern of drinking leading to BAC greater than or equal to 80 mg%.
5+ drinks for men
4+ drinks for women
in about 2 hours
How does SAMHSA define binge drinking?
5 + drinks for males, 4+ for women on the same occasion
How does SAMHSA define heavy alcohol use?
Binge drinking on 5 or more days in the past month
What is alcohol induced memory loss?
Periods of anterograde amnesia
Define alcohol induced memory loss
Amnesia for the events of any part of a drinking episode without loss of consciousness
How can it be difficult to tell if a blackout has occurred
If the person did not do memorable things
Describe the steps of memory formation
Encoding > storage > retrieval
Why might free recall be difficult after drinking?
Alcohol may disrupt processing of context for the formation of an episodic memory
What are the two types of memory loss?
En-bloc
Fragmentary
What is en-bloc memory loss?
Usually permanent
What is fragmentary memory loss?
Occurs more frequently
Recall can occur, often with various cues
What factors are associate with blackouts?
Large quantities of alcohol
Rapid rise in BAC
Drinking spirits
Gulping drinks
What is knowledge of drug effects on psychomotor performance useful for?
Psychopharmacologists who conduct research on behavioural effects of psychoactive substances
Clinicians who prescribe potentially impairing drugs
Forensic toxicologists who want scientidic data from studies to support opinions
What types of measurement were used in the impaired driving study?
Divided attention
Reaction time
Logical reasoning
Time estimation
Vigilance
Choice reaction time
What is risk-taking defined as?
Embarking on a task without certainty of success
Describe the study design for the impaired driving study.
Experienced bus drivers
Average 45 years old
Drinking history
Abstinence to an average of 30 pints/week
Describe the risk assesment process in the impaired driving study.
Drivers sat in drivers seat and were told they were about to drive bus between two posts. had to tell investigators how well they think they could do.
asked, how many times out of 5 could you drive through the post.
The smallest gap they would attempt to drive through
The actual performance
What were the results of the impaired driving study?
As BAC increased they were prepared to drive through a smaller gap
As BAC increased they needed a wider gap to succeed
Involvement in hazard increases as BAC increases
