drug addiction Flashcards
what are three preventable causes of death?
smoking, obesity and alcohol
what drug is associated with schizophrenia development later in life and what is the time frame for this risk to be high
cannabis
before adolescence there’s a higher risk than after adolescence
what is the definition of drug addiction?
its a chronic relapsing disorder characterised by compulsion to seek and take the drug, loss of control in limiting intake and emergence of negative emotional state (anxiety, irritability)
what is the medical term for drug addicition
substance use disorder
what are the diagnostic criteria of substance use disorder according to the DSM-5?
taken in larger amounts than intended
tolerance
withdrawal
craving
prolonged use of drug
what are factors contributing to vulnerability to developing drug addiction
-genetic (50-60%) (SNPs with certain genes associated with the reward system)
-environmental (stress, socioeconomic factors, complex family dynamic)
-drug-induced effects (induces chemical alterations in brain chemistry)
decribe the stages of addiction cycle
-starts during adolescence (peer pressure), and that addiction can develop
-it will then become a normal recoreational drug use
-a small percentage of people will escalate into using excessive amount to achieve the same euphoric effect (tolerance)
-Once you limit intake, this can cause low moods due to increase in noradrenaline, which can lead to withdrawal symptoms such that it can lead to a dependence of this drug
-such that if you limit intake, you will develop withdrawal symptoms (emotional and physical)
-this can trigger relapse
what are the withdrawal symptoms
emotional
-depression
-anxiety
-low mood
-irritability
-antisocial
physical
-sweating
-tremors
-nausea
-vomiting
-drinking
-abdominal pain
-joint aches
explain what tolerance is
when a larger intake of drug is required to achieve the same euphoric or pleasurable effect when first taken.
as drug use usually acts on opioid receptors.) which is a GI-coupled receptor—reduces adenylate cyclase and, in turn turn, reduces levels of CAMP and decreases calcium influx—inhibitory effect, so when you over stimulate this system, it leads to desensitisation, which reduces response of system, such that when you limit drug intake (leading to tolerance)
explain what is dependence
develops from repeated drug administration when an individual stops taking drug, which leads to the development of withdrawal symptoms.
(as drug use usually acts on opioid receptors.) which is a GI-coupled receptor—reduces adenylate cyclase and, in turn turn, reduces levels of CAMP and decreases calcium influx—inhibitory effect, so when you over stimulate this system, it leads to desensitisation, which reduces response of system, such that when you limit drug intake, this will reverse, causing an increase in adenylate cyclase, increase of CAMP hence increase in noradrenaline, which makes you susceptible to withdrawal symptoms
Thus, you develop dependence to avoid these symptoms.
what are the different brian circuits associated to drug addiction
reward system, involving the ventral tegmental area where the dopaminergic cell bodies are located, that projects onto the nucleus accumbens to release dopamine upon stimulation, to provide a pleasurable effect.
amygdala, which is involved in emotion regulation, including processing emotions such as fear, which has to do with the emotional attachment to drugs that you are afraid of letting go of.
hippocampus, which is involved in learning and memory and with drug users, they have memories of how it first felt when they took the drug so they keep going back to enjoy it again.
frontal cortex and anterocinggulate cortex that project onto the orbitofrontal cortex, these areas are involved in decision-making, the orbitofrontal cortex is involved in salience attribution and impulses (Giving value to the reward)
caudate putamen, which is part of the striatum and involved in habitual formation.
what type of drug is an amphetamine and its mech of action including its pharmacological effects and therapeutic uses
its a psychostimulant
It works by displacing dopamine from their vesicles to leak them out of the cell into the synaptic cleft to induce a pleasurable effect.
pharmacological effect
-increase alertness
-increase excitement
-can lead to anorexia and decrease hunger
-lack of satiety
therapeutic uses
-ADHD and narcolepsy
what type of drug is cocaine and its mech of action including its pharmacological effects
cocaine is a psychostimulant
It works by blocking the DAT (dopamine reuptake transporters) to prevent its reuptake and increase its levels in the synapse.
blocks catecholamine reuptake (dopamine and adrenaline)
pharmacological effect
-heightened pleasure
-euphorica
what type of drug is heroin and its mech of action including its pharmacological effects
its an opioid that binds to MOP which is a mu opioid receptor found in the ventral tegmental area on gabaergic neurons, which binds to it and blocks release of GABA, therefore removes inhibitory effect on dopaminergic neurons such that dopamine is released in nucleus accumbens for that pleasurable effect.
what type of drug is alcohol and its mech of action
its depressant
works by enhancing function of gabaergic gaba a receptors which is inhibitory increasing influx of chloride ions leading to hyperpolarization and can lead to inhibition of brains function
what type of drug is nicotine/tabacco and its mech of action including its pharmacological effects
social drug
works by binding to alpha 4 beta 2 nicotinic receptors which is found presynaptically on dopaminergic neurons to increase release of dopamine from nucleus accumbens.
pharma effects
-increase alertness
-decrease irritability
what is the effect of opioids and cocaine on the HPA axis and what are some pharmacotherapy interventions?
opiod inhibits HPA axis, leading to dysregulation and problems with stress-coping mechanisms due to low cortisol levels
Cocaine leads to hyperactivation of HPA axis, leading to dysregulation and increased stress.
Pharmacotherapy is used to treat this neurocrine disorder by reversing the dysregulation back to normal, which can be done by CRH competitive antagonists binding to the anterior pituitary and displacing CRH to reduce the hypersensitivity.
what are the physical brain alterations as a result of substance abuse?
PET scans show that through biomarker radiotracers, there has been a reduced level of D2 receptors, With repeated drug use, there can be downregulation of D2 receptors as the brain attempts to adapt to the constant influx of dopamine from drug use. This downregulation may result in a decreased response to the drug over time, leading to the need for higher doses to achieve the same effects, as well as withdrawal symptoms when drug use is discontinued.
hypofrontality (reduced cerebral blood flow) of frontal cortex, which may explain the reduced efficiency in decision-making and hence their compulsive behaviours.
upregulation of alpha 4 beta 2 in smokers.
what factors can cause relapse?
drug-related cues, stress and glutamate might be involved, so thats why they are developing drugs to interfere with glutamatergic system
what are the differences seen in addicts and non-addicts
addicts
- are projects from the reward system that project to different parts of the brain, including PFC and ACC, that further project to OFC which have shown decreased connectivity, which explains the reduced efficacy of decision-making abilities.
also projects from reward system to hippocampus, amygdala and striatum with stronger connectivity compared to non-addicts.
