25.1 Mood Disorders Flashcards
What are the three most common types of mood disorders?
Unipolar depression
Bipolar depression
Anxiety-related disorders
Which clinical condition mimics depression?
Hypothyroidism
What comorbidities is depression associated with? Why?
Associated with a range of comorbities and altered states that increase the likelihood of death (lowered numbers of lymphocytes, increased proinflammatory cytokines such as IL-6)
Cardiovascular disease
Type 1 diabetes
Slower wound healing
Increased suseptibility to infection
More likely to suffer from substance abuse
What is the biopsychosocial model for depression which predisposes someone to depression?
fMRI shows decreased prefrontal cortex activation
Decrease in reward, mood and motivation
What are the three theories on the neurological changes take place within the brain?
-Change in neurochemistry: reduced activity of neurotransmitters dopamine and serotonin
-Changes in the hypothalamic-pituitary-adrenal gland axis, with stress altering signalling cascades
-Neuropsychological: alteration in the way that social interactions are interpreted (increased likelihood that an event is viewed as negative)
Which famous theories have been linked to depression?
Beck’s (1967) theory of cognitive depression (more likely to see negatives)
Seligman’s theory (1975) of learned helplessness
Define what is meant by bipolar disorder
Mood instability which allows for rapid change between depressive and manic states for an individual
How do we know that BPD is different to depression?
Antidepressants have a markedly reduced effectiveness
What is anxiety? What type of physiological response does it bring about?
Attention focuses on perceived danger
Increase in symapthetic drive (heart rate, sweating, butterflies in stomach, blood to muscles)
Strong urge to avoid
What is the cognitive theory of panic disorder?
Persistent panic attacks result from catastrophic misinterpretation of benign body sensations
Sensations that are misinterpreted are mainly those involved in normal anxiety responses
Misinterpretation involves believing the sensations indicate an immediate physical or mental disaster
What is the monoamine theory of depression?
Depression is caused by a functional deficit of the monoamine transmitters (NA, 5-HT) whereas mania results from an excess
Supported by the use of drugs which alter monoamine transmission
Name the main classes of antidepressant drugs (4)
-Tricyclic antidepressants
-Selective 5-HT reuptake inhibitors (SSRIs)
-MAO inhibitors
-Selective serotonin and noradrenaline reuptake inhibitors (SNRIs)
How do tricyclic antidepressants work?
Competitive inhibitor of noradrenaline and 5-HT reuptake
Name a TCA?
Tricyclic antidepressant:
Amitriptyline
What is the mechanism of action of SSRIs?
Highly selective 5-HT reuptake inhibitors
Increase 5-HT within the synapse
What are the downsides of SSRIs?
Not beneficial for mild depression
Prolonged drug treatment results in desensitisation of the receptors
Increased activation of somatodendritic 5-HT1A receptors in the raphe neurons inhibits their normal 5-HT release lowering 5-HT
Name an SSRI?
Fluoxetine (Prozac)
What is the mechanism of action of MAO inhibitors?
Monoamine oxidase is an enzyme which breaks down cytosolic stores of noradrenaline and 5-HT in nerve terminals
Inhibiting the enzyme increases the abundance inside of nerve terminals ready for release
What is the mechanism of action of SNRIs?
Non selective 5-HT and NA uptake inhibitors
Where do barbiturates act on the GABA receptor?
Agonist to the allosteric site which increases the open probability of GABA
(also block AMPA and kainate receptors)
Where do benzodiazepines act on GABA receptors?
Binds across the interface of the alpha and gamma subunits
Act as a positive allosteric modulator to facilitate the opening of GABA channels
Where are 5-HT1 receptors expressed?
On the soma and dendrites of 5-HT producing neurons where they function as inhibitory autoreceptors
Expressed in the cortico-limbic circuit
5-HT1 is coupled to Gi
