Topic 4 Flashcards
Addiction Defintion
Compulsive drug seeking behaviour and abuse
even when facing negative health affects
Acute affect of drug taking
Getting high
caused by changes in neural transmission
i.e changes in the amount of neurotransmitter being released or changes to the activation of receceptors
Long term effects of dug taking
Altered brain function
neuronal death
changes to white matter in the brain
adaptations at the molecular level
Reward circutory
Located in midbrain
Ventral Tegmental - releases dopaminergic neurotransmitters - these go to the nucleus accumbens and frontal cortex - release of dopamine in these areas causes pleasure - therefore reinforces the behaviour
Taking drugs increases the dopamine releases
stimulant
increases energy
depressant
Decreases energy
Reasons to take drugs
Stress, depression, social anxiety, curiosity, athletic performance
Characteristics of drug addiction
Dependency
Tolerance
Withdrawal
Dependancy
Occurs after chronic drug use causes physical adaptations to the brain. The brain essentially gets use to the drug being in the brain and therefore can’t function without the presence of the drug
Tolerance
When the user has to take a higher dose or use a drug more frequently to achieve the same high
Withdrawal
Is a sign that the body has become dependent on the drug
the person will exhibit negative affects when not taking the drug
Loss of control
Hallmark of addiction
due to structural and functional changes to the dorsolateral prefrontal cortex - the part of the brain that is responsible for judgement, planning and decision making
Factors influencing addiction
Genetic - genetic heritability, neuropsychiatric disorders ie anxiety, ADHD, PTSD or depression
Environmental - Issues with early life or school life, low socioeconomic, peers taking substances, lack of parental supervision, exposed to parents taking drugs at an early age, physical or sexual abuse
Reward circuitry name
Mesocorticolimbic Dopaminergic Reward System
Parts of MesoDopa reward system
1) Mesolimbic pathway = VTA to Nuclous accumben
2) Mesocortico pathway = VTA to prefrontal cortex
VTA
Ventral Tegamentum
Heroin and nicotine affects
Acts on dopaminergic receptors on cell body and dendrites - stimulates these receptors
Alcohol and cocaine affects
Blocks dopamine reuptake in synapse - binds to the dopamine transporters, preventing the dopamine from binding to them
Substantial Nigra
Apart of basal ganglion (grey matter)
responds to dopamine
Plays a role in motor control
Striatum
Apart of basal ganglia
responds to dopamine
Plays a role in emotional response
Classical Conditioning
When an environmental cue becomes associated with a behaviour
Drugs of abuse
All can cross the blood-brain barrier
all have an increasing effect of dopamine in the reward circuitry
All have similar structure to neurotransmitters
All either mimic, enhance or block action of neurotransmitters
They act on specific targets - normal drugs lack specificty
Hallucinogens and Dissociative drugs
Distort an individuals perception of reality
Many are found in nature - psilocbye and peyote
2 classes - classic hallucinogens and dissacotiatives
Classical Hallucingens
Act on pre-synaptic serotonin receptors
structure is very similar to serotonin
I.e LSD, peyote
cause profound distortions of reality
Dissocitaives
All man-made
PCP, Ketamine
disrupts the action of glutamate at the NMDA receptor (learning and memory)
All made to be anaesthetics
Disort perception of sight and sound
Stimulants
All structurally similar to dopamine
Amphetamines, methamphetamines, cocaine, caffeine, nicotine
developed as therapeutic drugs originally
All are highly addicitve
Cocaine
Acts on all dopamine transporters but specifically the ones in the rewards system - more specifically in the nucleus accumbens
binds to dopamine transporters which block their reuptake, prolonging their affect in the synapse
Forms of cocaine
Water-soluble hydrochloride salt - the powder form
water-insoluble cocaine base - crack/ is smoked
Methamphetamine
Stimulant
derivative of amphetamine but stronger as it is more potent, meaning higher concentrations can penetrate the blood-brain barrier, it also lasts in the synapse for longer
causes brain damage - specifically to the neuron terminals
acts like cocaine but also increases the release of dopamine
talkative, restless, decreased appetite
MDMA
aka ecstasy
affects both serotonin, dopamine and noradrenaline
stimulant and psychedelic - affects multiple neurotransmitter systems
enhances release of neurotransmitters and blocks their reuptake
mood elevating due to serotonin - however, when drug wears off serotonin stores become depleted - causes negative effects of confusion, restless and depression
Nicotine
affects nicotinic receptors
stimulant
agonist of nicotinic acetylcholine
increase dopamine and stimulate reward pathway
very short lasting - hence why need to smoke every couple of hours
smoking allows rapid dissapation of nicotine in cns
long-term effects of MDMA
brain damage, cognitive issues, tachycardia, kidney dysfunction, high blood pressure
Inhalants
solvents, areosals, gases, nitrates
absorbed rapidly by bloodstream but only last a few minutes
CNS depressant
slurred speech, euphoria, delsuion, light headedness
alcohol
affects all organs but primarily the brain
depressant
causes inhibtion and supresses brain functinon
affects a number of different targets ie transporters and receptors
main ones are GABAa receptor, NMDA receptor and dopamine transporter
acute effects: impaired coordination, poor judgment, affects learning and memory
long-term effects of alcohol
brain builds up tolerance to alcohol
changes in gene expression
genes that code for the receptors and transporters that alcohol effects will be downregulated to lessen the affect and so that there are fewer targets avaliable
after a long period of time these changes will be irreversible
Diagnosing Alcohol dependance
Must have at least 3 of the following:
Development of tolerance
withdrawal symptoms
loss of control
unsuccessful attempts to stop or minimise. alcohol consumption
changes in lifestyle, ie social withdrawal
continuing to use despite negative health consequences
Alchohol Metabolism
Alcohol to acetaldehyde via alcohol dehydrogenase
acetaldehyde to acetate via acetaldehyde dehydrogenase
Affects of alcohol on the brain
Loss of grey and white matter
enlarged cerebral ventricles
brain mass shrinkage - this is reversible
Alcoholism symptoms
4 major symptoms
craving
loss of control
tolerance
physical dependance
Molecular targets of alcohol
GABA A receptor
NMDA receptor
Dopamine Transporters
Effects on GABA A receptor
alcohol is an allosteric modulator
increases action of receptor by increasing its affinity for GABA, hence leaving the cl- gates open for longer
this increases the sedative effects
Effects on NMDA
NMDA is excitatory
alcohol directly inhibits its function
creating a sedative effect
when alcohol is removed causes a surge in glutamate - this causes an over excitatory response and can lead to seizures
Effects on dopamine transporter
Increases dopamine release and blocks the re-uptake of dopamine
when you stop drinking dopamine release is decreased and re-uptake is increased
Treatments for Alcoholism
Detox given with a benzodiazapene
AA and therpay
Pharmological
Pharalogical treatments for alcoholism
Benzodiazapene
Naltrexone
Acamprosate
Disulfram
