Addiction Flashcards
Give examples of addictive drugs in clinical use (3)
e.g., opiates for pain relief,
Ritalin® to calm behaviour in children with ADHD,
cannabis oils to treat rare forms of epilepsy in children or muscle spasms caused by multiple sclerosis
Give examples of addictive substances being present in over the counter products in the last century (4)
cocaine for toothache,
heroin products for coughs and colds,
Mrs Winslow’s morphine-based soothing syrup for teething in babies,
the alcohol-laced ‘Malt Nutrine’ to aid digestion in toddlers
How is addiction diagnosed
11 point scale given in the DSM-V
mild: 2-3 symptoms; moderate: 4-6; severe: 7-11
How does the criteria to diagnose addiction differ in the newer DSM from earlier versions
In the earliest versions of DSM, the symptoms of tolerance and withdrawal were emphasised
more recent iterations of DSM stress the pre-occupation of individuals to acquire drugs, maladaptive decisional processes, and continued use despite increasingly adverse consequences of out-of-control drug use
Why were tolerance and withdrawal emphasised in the earliest DSM
defined by increasing levels of drug intake to maintain the same subjective experience, and which often co-occurs with a defined withdrawal syndrome – a set of symptoms triggered by the abrupt discontinuation of the drug (e.g., nausea, diarrhoea, seizures, irritability)
Give the NHS and WHO definitions for addiction
NHS: “as not having control over using a drug to the point where it could be harmful to you”
WHO: “as a syndrome in which the use of a drug is given a much higher priority than other behaviours that once had a greater
value”.
What proportion of the population does addiction affect
15-20%
Give some risk factors of addiction (7)
age of first use (early onset carrying greater risk),
gateway drugs (e.g., nicotine, cannabis –though controversial),
gender (females > males),
socioeconomic circumstances (including poverty),
aberrant stress coping mechanisms,
pre-morbid traits
(anxiety, impulsivity, thrill seeking),
various co-morbid disorders such as conduct disorder, personality disorder, and ADHD
individual propensity for addiction is likely determined by a balance between risk and protective markers, which may be inherited or shaped by the environment
What is interesting about ADHD being a risk factor for addiction
ADHD is often treated with drugs that have a high abuse liability such as amphetamine
may be self medicating underlying deficits in temperament, perhaps aspects of arousal and attention.
eg stimulants may be taken to improve attentional focus by reducing distractibility
Is addiction based off nature or nuture?
shaped by both biological (genes) and environmental variables (in a roughly 50/50 manner)
How was dopamine discovered to be a dominant neurochemical of the reward pathways
intra-cranial self-stimulation (ICSS)
Which part of the brain has addiction research been focussed on
dopamine system
nucleus accumbens (NAc), a key forebrain region of the reward system, together with dopamine inputs to this region,as the primary substrates underlying the addictive properties of drug
Why was the idea that NAc and its dopamine inputs involvement in addiction given added momentum?
all drugs of abuse, following an acute injection, increase dopamine release in the NAc
What is the role of dopamine in reward pathways?
dopamine does NOT signal reward per se (or more precisely pleasure) but it does play a role in reinforcement learning – in other words in learning the predictive relations of reinforcers in the environment
What did Schultz discover about dopamine
dopamine neurons encode reward prediction errors that enable learning to reward-related cues
Describe dopaminergic neuron activity during reward presentation
dopamine neurons are active during the initial presentation of a reward, but habituate when the reward is fully predicted.
Activity then shifts to stimuli that predict the onset of a reward but decreases when expected reward are not delivered.
By increasing dopamine release, drug rewards are always better than expected
What is the incentive salience sensitization theory
repeated exposure to drugs ‘sensitizes’ the mesolimbic dopamine system (ventral tegmental area → NAc) and in turn a motivation system that attaches valence to stimuli associated with drugs.
What was Jane Stewart’s variation of the incentive salience sensitization theory (3)
discrete and contextual stimuli in the environment gain motivational significance through conditioning (i.e., they become incentives in their own right), and trigger feelings of craving and internal ruminations about the next drug binge
repeated drug
exposure progressively elevates dopamine release in the mesolimbic system, thereby
contributing to subjective feelings of ‘wanting’
indicated a clear separation between the motivation to seek drugs and the accompanying hedonic state
Jane Stewart suggested, in dopamine, there is a clear separation between motivation to seek drugs and the hedonic state. Is there any evidence to support this
orally elicited ‘liking’ and ‘disgust’ responses were unaffected by the almost complete removal of dopamine from the striatum, and in fact were even slighted elevated!
this rules out an involvement of dopamine in hedonic reactions that instead implicate the endogenous opioid systems
What are some problems with the incentive salience sensitization theory (3)
based on the behavioural response of rodents to repeated injections of drugs (↑ locomotor activity) that were given by the experimenter (not subject)
little evidence in humans that the mesolimbic dopamine system sensitizes with drug exposure
theory predicts that all individuals exposed to drugs would be become addicted
What is the evidence in humans that the mesolimbic dopamine system sensitizes with drug exposure?
V little evidence for this
In fact, the opposite appears more likely with dopamine neurons becoming ‘exhausted’ with repeated cycles of bingeing and withdrawal
Give 3 major theories of addiction
Incentive salience sensitization theory
Opponent process theory
Maladaptive conditioning theory
What does the opponent process theory of addiction postulate
drugs engage two motivational systems, the first mediating positive reinforcement (people seek drugs as rewards to achieve a positive affective state), the second mediating negative reinforcement (people seek drugs to escape from the unpleasant symptoms of withdrawal). With continued drug use, tolerance develops to the positive effects, which encourages drug binges, while in the background, a deepening negative affective state develops. Eventually, negative reinforcement mechanisms come to dominate behaviour
Describe the roles of different molecules in the opponent process theory
in anti-reward state: CRF, NA, and dynorphin upregulated
there is also a theorised reduction in dopamine and opioids that underlie reward state
