Neurobiology of addiction Flashcards
What is addiction?
complex condition complicated by social/psychological confusion
- drug abuse/misuse = inappropriate risk use of drugs which produces clinical consequences
What is encompassed under non-prescribed drugs?
Drugs of abuse
Illegal drugs
But also includes alcohol
What is encompassed under prescribed drugs?
These are drugs prescribed by HCP but they can also be misused
What are some example drugs with addictive potential?
MDMA, cocaine, amphetamines, inhalants, opioids, LSD, caffeine, cannabinoids, nicotine
Is there a common biological process with addictive substances?
different pharmacological targets at the cellular level, affecting different neurotransmitter systems
different abuse potential = recreational to dependence
What is another term for pleasure induced by drugs of abuse?
hedonism
when people experience this from a substance they are more likely to expose themselves to the substance again
What underlies the feeling of pleasure?
Dopamine and the mesolimbocortical system
DA pathway - nigrostriatal
- reward (motivation), pleasure, euphoria, motor function, compulsion
5HT pathway
- mood, memory processing, sleep, cognition
Mesolimbic and mesocortical pathways are key in hedonism
How do the drugs produce this increase dopamine effect?
e.g. heroin and cocaine
Cocaine acts directly upon DA neurones in the nucleus accumbens = stimulating release
Heroin acts indirectly
- acts in the VTA first causing disinhibition = reducing release of GABA onto the DA neurones in the nucleus accumbens and therefore increasing the release of DA
What are some natural rewards that activate the DA reward pathway?
sex, food, water, caring for young, social interaction
What are the 3 factors that occur through chronic misuse of addictive substances?
Tolerance
Physical dependence
Psychological dependence
What is tolerance?
Purely biological description
- decline in the standard dose of the drug with continued use
- therefore dose may need to be gradually increased to maintain the effects
- multiple processes involved: behavioural, metabolic and neurobiology (adaptive process in which there is reduced DA transmission = change in synapses)
What are the implications of relapse?
common in heroin addiction
Overtime they have to take higher doses to gain the same effects
Once they’ve become clean they tolerance is reduced, however if they relapse they end up taking the same dose they used to which causes overdosing and this can be fatal
What is physical dependence?
Withdrawal symptoms
- short term for caffeine= headaches
Neurobiological adaptive process
What is psychological dependence?
Long term = decades
Craving/compulsion = urge
Impaired decision making - causes them to do bad things
Neurobiology- changes in physical structure
What is the difference between tolerance/physical dependence and psychological dependence?
tolerance/physical dependence = leads to physiological withdrawal = NEED
psychological dependence leads to craving = WANT
