The biomedical model Flashcards
what do models in psychology do?
3 points
models spell out:
* basic assumptions
* give order to the field under study
* provides a structured framework for scientific investigation
mental health models
what do models influence
4 points
- what investigators observe
- the questions they ask
- the information they seek
- how they interpret the data
what is the biological model
what does the biological model of metal disorders adopt?
a medical or biological perspective
biological model assumptions?
3 assumptions
- mental disorders are biologically-based brain diseases
- the underlying cause is organic
- mental disorders reflect a disturbance of brain structure and/or function
what is the biological model?
the biological model argues that there is no meaningful distinction between mental and physical disease
from the 1970s what was maladaptive behaviour?
maladaptive behaviour increasingly considered to be a function of an interaction between biological, psychological and social factors
the biological model today
metal disorders
the idea that mental disorders are biologically-based brain diseases remains very influential
the biological model today
pharmacological agents
the biological model reflected the increase use of pharmacological agents in mental illnesses (e.g. depression, anxiety)
the biological model today
research evidence
there is a large body of research evidence correlating mental functions and brain activity
mental disorders: biological causes
neurotransmitter imbalance: altered production (or release)
altered production (or release) of neurotransmitter at synapses, over-or under-stimulating the target neuron
mental disorders: biological causes
neurotransmitter imbalance: altered reuptake (or degradation)
Altered reuptake (or degradation) of neurotransmitters, increasing or decreasing concentration at synapses
mental disorders: biological causes
neurotransmitter imbalance: alterations in neurotransmitter receptors
Alterations in neurotransmitter receptors, so that they are abnormally sensitive or insensitive
mental disorders: biological causes
psychotropic drugs
many drugs used to treat mental health disorders act at central (brain) synapses by increasing or decreasing neurotransmission at particular synapses
mental disorders: biological causes
what do psychotropic drugs influence?
psychotropic drugs used in the treatment of mental disorders influence synaptic transmission
mental disorders: biological causes
psychotropic drug mechanisms
3 points
mechanisms:
1. increased or decreased transmitter synthesis/release
2. increased or decreased transmitter re-uptake/inactivation
3. direct stimulation or inhibition of transmitter receptors
drugs and mental disorders
some drug discovery sheds light on mechanisms of disease - or understanding disease mechanisms allows rational drug design
amine hypothesis of depression
resperpine (drug)
in the 1950s the drug resperpine was approved to treat high blood pressure. but some patients appeared to become depressed or suicidal
amine hypothesis of depression
what was the drug resperpine doing to the body?
the drug was found to work by depleting nerve cells of amine neurotransmitters (e.g. seratonin & dopamine)
amine hypothesis of depression
iproniazis (drug)
3 points
- late 1950s - anti-tuberculosis drug developed (iproniazis)
- side-effects: euphoria, increased apetite and improved sleep
- it increased amine neurotransmitters - used to treat depression
amine hypothesis of depression
what is depression caused by?
deficiency of amine neurotransmitters
how do anti-depressants work?
they work by correcting brain ‘amine deficiency’
amine hypothesis of depression
what are most antidepressants?
- serotonin-selective reuptake inhibitors (SSRIs)
amine hypothesis of depression
what does blocking re-uptake of serotonin do?
increases its concentration at the synapses in the brain
amine hypothesis of depression
what was the most perscribed drug in the US
Zoloft (sertraline)
criticism of the amine hypothesis
oversimplification
4 points
- methodological problems
- inconsistent findings
- discredited serotonin hypothesis
very small sample sizes, poor control of confounding variables
other mental health disorders
depression
symptoms due to deficiency of monoamine transmitters: noradrenaline, serotonin
other mental health disorders
schizophrenia
core psychotic symptoms such as delusions and hallucinations are due to excess brain dopamine
other mental disorders
obsessive-compulsive disorder (OCD)
symptoms caused by dysfunction in brain pathways regulated by serotonin
biological models are complex
issues with accounts of biological models of disease:
they are often highly simplistic and misleading
biological models are complex
issues with biological disease models:
they are highly complex and sophisticated and are supported by extensive research evidence spanning many decades:
* genetics
* structural and functional brain imaging
* autopsy and neurodevelopmental studies
* animal models
hormones in mental disorders
what does the endocrine system consist of?
glands that secrete hormones into the bloodstream
hormones in mental disorders
what are hormones?
chemical messengers that control bodily functions (e.g. sex, feeding)
hormones in mental disorders
what is the piturity gland?
the ‘master gland’ of the endocrine system
hormones in mental disorders
what is the piturity gland controlled by?
hypothalamus
hormones in mental disorders
hypothalamic-piturity-adrenal (HPA) axis
- over-active in stress, including chronic psychological stress
- leads to persistent elevation of the stress hormone cortisol in the bloodstream
- implicated in several psychological disorders (e.g. depression, anxiety)
genetic vulnerability
chromosomal abnormalities
complete or partial duplications/deletions (e.g. down syndrome: intellectual disability/dementia)
genetic vulnerability
single gene defects
abnormalities in particular genes (mutations) or disease associated normal variants (polymorphisms)
what are vulnerabilites to mental disorders?
they are ususally polygenic (influenced by multiple genes)
* there is not usually a single gene for a particular mental disorder
epigenetics
what are epigenetics?
when a person’s genetic code is fixed at birth, but genes can be switched ‘on’ or ‘off’ during life
epigenetics
how are genes silenced?
by adding molecular tags (methyl groups) to parts of the DNA strand
epigenetics
how is the pattern of gene methylation influenced?
it is influenced by the environment including early life experiences
epigenetics
what can adverse life experiences lead to
adverse life experiences (e.g. bullying, neglect) can lead to epigenetic changes that influence risk of mental health disorders in adulthood
gene-environment interaction
behaviour is not exclusively determined by?
the genes you inherit
* psychiatric disease risk depends on both genetic and environmental factors
biological model: treatment
AIM
target the underlying biological dysfunction
biological model: treatment
ULTIMATE GOAL
discover precise therpeutic agents that the target disease process without causing harm
biological model: treatment
MOST TREATMENTS
pharmacological
biological model: treatment
OTHER TREATMENTS
brain stimulation, surgery
insulin shock therapy
who created the insulin shock therapy?
Manfred Sakel (1933)
inslulin shock therapy
what was insulin shock therapy used for?
mainly used for schizophrenia in the 1940s and 1950s
insulin shock therapy
risks of insulin shock therapy:
obesity, seizures, brain damage or death
prefrontal leukotomy
who created prefrontal leukotomy?
Egaz Moniz
frontal lobotomy
who created frontal lobotomy?
Walter Freeman who performed 3500 lobotomies
frontal lobotomy
what did frontal lobotomy do?
reduced emotional distress and improved challenging behaviour but left patients ‘flat’, passive and unemotional
electroconvulsive therapy (ECT)
what was ECT?
controlled induction of convulsive seizured under general anaesthesia
ECT
what does ECT affect?
affects numerous neurochemical (neurotransmitter) systems
deep brain stimulation
stimulation of area 25
stimulation of area 25 in the limbic lobe of the brain is associated with dramatic mood improvement in severe depression
DBS
what is deep brain stimulation used for?
used for severe treatment-resistant conditions (e.g. depression, OCD)
* very expensive and carries risks associated with neurosurgery
transcranial magnetic stimulation (TMS)
what is transcranial magnetic stimulation used for?
used for treatment-resistant depression and anxiety disorder
transcranial magnetic stimulation (TMS)
how does TMS work?
electromagnetic coil delivers magnetic pulses to the brain - exact mechanism of action unclear
pharmacological treatments
psychotropic agents
any medication capable of affecting the mind, emotions and behaviour
pharmacological treatments
what are the most common forms of medical treatment for mental disorders?
4 points
- antidepressants (low mood)
- anxiolytics (anxiety)
- antipsychotics/neuroleptics (psychosis)
- mood stabilisers (bipolar disorder)
antidepressant agents
several types, acting on different neurotransmitters:
- patients do tend to improve
- side effecis: nausea, nervousness, insomnia, sexual dysfunction
antidepressant agents
commonly perscribed antidepressants:
4 types
- fluoxetine
- sertraline
- paroxetine
- citalopram
anti-anxiety drugs (anxiolytics)
when are anxiolytics used?
they are used if guided self-help and cognitive-behavioural therapy fails
anti-anxiety drugs (anxiolytics)
anxiolytics examples:
benzodiazepines (valium, xanax)
* sedative and muscle relaxing properties
* causes drowsiness and lethargy
* highly addictive, high relapse rates
antipsychotic drugs (neuroleptics)
what are neuroleptics used for?
they are used to treat psychotic disorders and act by blocking brain dopamine (and/or serotonin) receptors
* effective in reducing delusions and hallucinations
mood stabilisers
what is lithuim used for?
used to treat bipolar affective disorder
KEY POINTS: biomedical model
3
- biomedical model assumes that disorders have an organic or physical cause
- many treatments have been based in the biomedical model, of which some are now discredited
- treatments fall into 3 main categories: drugs, surgery and brain stimulation
KEY POINTS: Pharmacological interevntions
3 points
- pharmacological interventions are by far the most common
- they have revolutionalised the management and care of people with mental illnesses
- however, they are not cures
biomedical approach: advantages
biomedical approach advantages:
3 points
- suggests clear mechanism for most disorders: obvious improvement on ‘supernatural’ explanations
- effective in delivering insights into disorders with a clearer biological base (e.g. alzheimer’s disease)
- drug treatment has revolutionised patient care: it is generally effective (and faster) than other therapies
biological approach: advantages
treatment based on the scientific method
in theory this means treatments should only be adopted if proven effective
For example: antidepressants
* Meta analysis suggested SSRI antidepressants were no more effective than placebo, except in severe cases
* But another showed that patients are either responders or nonresponders
research evidence: explained
randomised control trial
ideally it should be ‘double blind’ RCT so that neither patient nor researcher know who is in the treatment (vs. placebo) groups
research evidence: explained
importance of meta analysis
a meta-analysis can be used to pool results from multiple trials
biomedical approach: limitations
assumes universality
- no room within its framework for social, psychological, or behavioural dimensions of disorders
- causality: cause by-product of disorder?
- redctionism: is psychology really biology?
biomedical model: controversy
CLAIM: Mental disorders are brain diseases caused by
neurotransmitter dysregulation, genetic anomalies, and defects in brain structure and function
Yet, scientists have not identified a biological cause of, or even a reliable biomarker for any mental disorder
biomedical model: controversy
CLAIM: Psychotropic medications work by correcting the
neurotransmitter imbalances that cause mental disorders
However, there is no credible evidence that mental disorders are caused by chemical imbalances, or that medicines work by correcting such imbalances
biomedical model: controversy
CLAIM: Biological psychiatry has made great progress in reducing the societal burden of mental disorder
However, mental disorders have become more chronic and severe, and the number of individuals disabled by their symptoms has steadily risen in recent decades
biomedical model: controversy
CLAIM: Educating the public that mental disorders are biologicallybased medical diseases reduces stigma
But, despite the public’s increasing endorsement of biological causes and treatments, stigma remains and shows signs of worsening
