Drugs and food Flashcards
What are 5 positive impacts of alcohol?
– Tax revenues from Alcohol in Australia have averaged around 6 Billion Dollars per year over the last decade
– Alcohol consumption reduces cardiovascular deaths by approximately 800 cases per year, and prevents around 20,000 hospitalisations
– It also acts to reduce kidney/gall-bladder stones and increases bone density
– Hotels can act as focal point for communities
– Alcohol consumption can be a pleasurable experience
What are 7 negative impacts of alcohol?
– 15% percent of men and women aged 20-29 drink at a rate likely to cause them harm (> 2 standard drinks/day).
– Among this age group 50% of men and 20% of women have engaged in binge drinking (> 7/5 standard drinks drunk consecutively) at least once a week in the past year.
– Harms from excessive intake include:
• Cirrhosis (liver damage)
• Heart disease
• Brain damage
• Road trauma
• Violent behaviour
• Relationship breakdown
• Lost productivity
– The rate of excessive consumption in Indigenous Australians is 2-3 times higher even though fewer drink
What are the metabolic effects of alcohol? (6)
• Metabolism and male vs female differences
– Alcohol enters the bloodstream and is rapidly absorbed by the brain, but much more slowly by muscle (women have less muscle)
– Alcohol is primarily (90%) metabolised by the liver (and 10% by stomach - but women are less efficient at this)
• Alcohol is broken down into Acetaldehyde (women less efficient at this as well)
• Acetaldehyde is broken down into Acetate
• Acetate is then fed into the ACoa pathway yielding 7Kcal for every gram of alcohol consumed
• The body can metabolise a maximum of 6-8g per hour
What are the psychological effects of alcohol? (6)
• General - euphoria, disinhibition, reduced anxiety, impaired motor control
• Specific - effects of alcohol need to be distinguished from peoples expectations of what happens on ingestion
– Expectation free research designs tell us that
• Alcohol lengthens reaction time
• Alcohol narrows attention
• Alcohol promotes risk taking
• Alcohol enhances aggression
– This makes for a very unfortunate cocktail when combined with a car and an inexperienced driver
What are the effects of alcohol on the brain? (7)
• Alcohol acts upon multiple brain systems, which is why it is called a promiscuous drug
• Its effects also vary by dose
• The key changes appear to be:
– It acts akin to anaesthetics by increasing the permeability of nerve cell membranes (consumption of the anaesthetic agent ether is also intoxicating)
• Alcohol can be used as an anaesthetic but its therapeutic dose is so close to its lethal dose it was never of much practical use
– It acts upon the same GABA receptors as anti-anxiety drugs such as diazepam (which is 4000X more potent)
– It alters brain dopamine levels, especially in the Nucleus Accumbens (driving wanting)
– It increases levels of endogenous opioids (producing liking)
What are the 2 types of tolerance we can have to alcohol?
• The behavioural and pharmacological effects of alcohol change with exposure - that is, tolerance
• Acute tolerance
– Within a drinking session rising blood alcohol (BA) correlates well with behaviour change. After drinking ends BA can still be elevated but there can be a disconnect between behaviour and BA:
• One can feel sober even with both an elevated BA and significant impairment in things like reaction time, attention etc
• The classic example is driving the morning after heavy drinking the night before – feeling sober, but impaired and with an elevated BA
• Chronic tolerance - metabolic and tissue
– Regular drinking affects the way the body metabolises alcohol and the way in which cells respond to the same level of alcohol. Chronic tolerance is lost after 3 weeks of abstinence in all drinkers
What is addiction to alcohol?
• Addiction is a problem in around 10% of regular drinkers
• It is defined by the American Medical Association as:
– Alcoholism is an illness characterised by a preoccupation with alcohol and a loss of control over its consumption, such as to lead to intoxication if drinking is begun; the condition is chronic, progressive, and has tendency to relapse. It is typically associated with physical disability and impaired emotional, occupational and/or social adjustment as a direct consequence of persistent and excessive use of alcohol
• Around 1 person in a 100 becomes an alcoholic
How does alcoholism affect neurology? (7)
• Wernicke-Korsakoff syndrome
• Two components that may occur alone or together
– Wernicke’s encephalopathy – dementia, ataxia, visual disturbances
– Korsakoff’s syndrome – anterograde amnesia (i.e., an inability to learn new things), confabulation, language difficulties
• Cause
– Chronic alcohol abusers tend to have poor diets, and hence have low intakes of thiamine (vitamin B1)
– Alcohol may interfere both with thiamine uptake and adversely affect metabolic pathways that are dependent on thiamine
– There may also be a genetic susceptibility
• Disease course is irreversible following amnesia/dementia onset
• Other neuro-degenerative disorders
– Marchiafava-Bignami disease – degeneration of corpus callosum and dementia
– Haemotomas – small blood clots resulting from frequent bumps to the head (occurring during intoxication)
– Hepatic encephalopathy, Central pontine myelinolysis, Alcoholic cerebellar degeneration, Alcohol related dementia
What are the withdrawal symptoms from alcohol?
– Mild (tremor, anxiety, insomnia)
– Moderate (severe tremor, convulsions, hallucinations [typically in peripheral vision])
– Severe – AKA Delirium tremens (confusion, persecutory hallucinations, systemic circulatory problems, status epilepticus; 15% mortality if untreated)
– Gets worse with repeated cycles
What other health problems can alcoholism cause? (8)
– Cardiomyopathy, myopathy, hepatitis, cirrhosis, impotence, sterility etc
– Cancer of mouth, tongue, oesphagus
• 5x base rate in heavy drinkers, 8x base rate in smokers, 44x base rate in heavy drinkers & smokers
• Fetal alcohol syndrome
• Characterised by facial abnormalities (absent philtrum, flattened bridge) and significant developmental delays of varying severity
• 6% of alcoholic mothers (heavy consumption during 1st trimester)
• 1200 cases (?) per year in US
• Lifelong social and intellectual disability
What are the risk factors for alcoholism? (3)
• Several lines of evidence suggest genetic susceptibility
• Increased risk in offspring of alcoholics
• Risk higher if both parents alcoholic
Risk the same if offspring raised by non-alcoholics
• No risk (relatively) for the offspring of non-alcoholics adopted by alcoholic parents
• Higher concordance in MZ than DZ twins
– Individuals with alcoholic relatives show:
• Less sensitivity to low levels of alcohol
• Abnormalities in DA receptors (wanting)
• Abnormalities in 5HT metabolism (relating to heightened risk for anxiety, depression and impulsivity)
• Genes combined with…
– Drinking culture
• Socially sanctioned
• Widespread availability (the outlet effect)
– Comorbid conditions
• Alcoholism tends to be comorbid with anxiety disorders such as panic attacks, OCD and phobias - self medication
• Alcoholism results from an unfortunate synergy of genetic predisposition (alcohol or non-alcohol related) combined with our alcohol tolerant culture
How do we treat alcoholism?
• Pharmacological
• Acute withdrawal (Benzodiazepines)
• Chronic
– Disulfiram (antabuse) which prevents reduction of acetaldehyde
– Naltrexone which appears to be useful in preventing relapse by reducing craving (as with tobacco)
• Psychological
• AA, Therapy (varied), Relapse prevention training
• The long-term (4 year) spontaneous abstinence rate is around 30%. Virtually no treatment appears to exceed this benchmark, although drug/psychological therapies may assist continued abstinence
What are the psychological effects of caffeine? (6)
• Cognitive
– Decreases reaction time
– Attentional effects
• Increases vigilance (especially on monotonous tasks)
• Benefits both endogenous (voluntary capacity to direct attention) and exogenous (ability to attend to external events) attention
• Mood
– Increases feelings of alertness
– Increases feelings of subjective wellbeing
• It exerts these effects equally in both sleep deprived and non-sleep deprived individuals
• Important caveat!
– There is much uncertainty as to whether the cognitive and mood effects of caffeine JUST reflect the alleviation of withdrawal symptoms. This is because almost everybody consumes caffeine.
What are the physiological effects of caffeine? (7)
• Mild diuretic
• Increases blood pressure, heart rate
• At high doses, tremors, anxiety, racing heart
• Some evidence for adverse effects on pregnancy
• Adenosine (involved in energy metabolism) increases during the day and is elevated whilst asleep. Caffeine prevents adenosine binding to its receptor
• Caffeine also interacts with GABA receptors, slowing the binding of benzodiazepines and other hypnotic agents
• It indirectly modulates striatal dopamine and MAY potentiate the effects of certain addictive drugs
Is caffeine addictive?
• Is it abused?
• In very rare instances (caffeine intoxication >1000mg/day)
• It does not appear to produce a high and animals do not self administer this drug, but it is a positive reinforcer in animals and people (i.e., both like it)
• Tolerance?
• There is some evidence of acute tolerance but little or no evidence of chronic tolerance
• Withdrawal?
• Many suggest there is a withdrawal syndrome
– Headache, fatigue, cognitive dulling, low mood, which are readily alleviated by consuming caffeine
• This is disputed by others
– Some say these symptoms are expectancy effects
– A prior headache history may predict this particular symptom
– Guatemala study - heavy coffee intake in kids (6x adult US consumption) followed by abrupt cessation found no withdrawal symptoms
