S11) Anxiety Disorders Flashcards
What is the limbic system?
- The limbic system is a set of brain structures located on both sides of the thalamus, immediately beneath the cerebrum
- It supports a variety of functions including emotion, behavior, motivation, long-term memory, and olfaction
Identify the components of the limbic system
- Hippocampal formation
- Septal area
- Amygdala
- ± Prefrontal cortex
- ± Cingulate gyrus
hippocampus
o Receives inputs from many parts of the cortex, processes emotional content
o projects to thalamus and hypothalamus = autonomic features of emotional response
o Memory
elaborate on how hippocampus causes autonomic features of emotional response
→ projects to the hypothalamus: hypothalamus sends projections down cord to autonomic preganglionic neurones (hypothalamospinal tract)
= sympathetic nervous system activation and release of adrenaline
Amygdala
- almond shaped near tip of hippocampus
- receives many inputs from sensory system
- output to the cortex and the hypothalamus
- involved in behaviour and autonomic emotional response
prefrontal cortex
→ emotion
describe the endocrine element of the stress response
→ limbing system acts on hypothalamus = secrete stress hormones
→ via hypothalam-pituitary adrenal axis
→ release of cortisol from adrenal cortex
what are the three stages occurring in the body after prolonged exposure ti stressors
- alarm reaction
- resistance
- exhaustion
describe the alarm reaction
release of adrenaline and cortisol and sympathetic activation
Briefly outline the functioning of the limbic system
Briefly outline the limbic-hypothalamo- pituitary-adrenal axis
What are the actions of cortisol?
- Increase of energy metabolite levels
- Suppression of immune system
- Inhibition of allergic and inflammatory processes
What are the three components of the general adaptation syndrome?
Which three process occur in the alarm reaction part of general adaptation syndrome?
- NA release from sympathetic nerves
- Adrenaline and NA release from adrenal medulla
- Cortisol release from adrenal cortex
What occurs in the resistance part of general adaption syndrome?
Resistance – action of cortisol is longer lasting than adrenaline, allows maintenance of response to stress
What occurs in the exhaustion part of general adaptation syndrome?
Exhaustion – prolonged stress causes continued cortisol secretion, leading to muscle wastage, suppression of immune system and hyperglycaemia
What is anxiety?
Anxiety is a feeling of worry, nervousness or unease about something with an uncertain outcome
What are the symptoms of anxiety?
- Palpitations
- Sweating
- Trembling
- Difficulty breathing
- Chest pain
Identify six different types of anxiety disorders
- Social phobia (social anxiety)
- Specific phobias (spiders)
- Generalised anxiety disorder
- Panic disorder (panic attacks)
- Obsessive compulsive disorder (OCD)
- Post-traumatic stress disorder (PTSD)
In terms of the functional neuro-imaging, explain the effect of common anxiety disorders on the following parts of the brain:
- Amygdala
- Cingulate cortex
- Hippocampus
- (+) Increased function
- (-) Decreased function
- (-/+) Both increased and decreased function
- (?) Too little information
Explain the relationship between GABA levels and anxiety (and the treatment of such)
- GABA levels are decreased in cortex in patients with panic disorder
- Benzodiazepines increase GABA transmission so reduce anxiety (serotonin)
Explain the relationship between serotonin levels and anxiety (and the treatment of such)
- Increased levels of serotonin (due to SSRIs) may stimulate serotonin receptors in hippocampus
- Leads to neuroprotection, neurogenesis and reduction of anxiety
Benzodiazepines should not be used in the long-term of anxiety disorders.
In light of this, discuss other treatment options
- SSRIs (mainstay) / pregabalin (GABA analogue)
– Short term benzodiazepines
- Cognitive behavioural therapy
– group therapy
Briefly illustrate the steps involved in cognitive behavioural therapy
What is an obsession?
An obsession is a thought that persists and dominates an individual’s thinking despite their awareness that the thought is either entirely without purpose, or has persisted and dominated their thinking beyond the point of relevance or usefulness
What is a compulsion?
A compulsion is an obsessional motor acts which may result from an obsessional impulse that leads directly to the action, or they may be mediated by an obsessional mental image or fear
E.g. I need to turn the light switch on and off ten times or my family will die
Obsessions and compulsions share some features.
Describe four of them
- Originate in the mind of the patient
- Repetitive and unpleasant
- Acknowledged as excessive or unreasonable
- Patient tries to resist, but at least one obsession/compulsion is unsuccessfully resisted
What is the diagnostic criteria for obsessions / compulsions?
- Carrying out the obsessive thought/act is not pleasurable
- Obsessions/compulsions must cause distress / interfere with the patient’s social or individual functioning
- Obsessions and/or compulsions present on most days for a period of at least 2 weeks
Identify three suggested theories for the pathophysiology of OCD
- Re-entry circuits in basal ganglia
- Reduced serotonin
- PANDAS occur after a streptococcal infection
– autoimmune aetiologies (cross-reactivity with certain streptococcal antigens and the basal ganglia)
In terms of the following layout, illustrate how the pathophysiology of OCD might be due to re-entry circuits in the basal ganglia
→ obsessional thoughts re enter the cortex due to overactivity
What is PANDAS?
Paediatric autoimmune neuropsychiatric disorder associated with streptococcal infection is a hypothesis that children develop OCD / tic disorders due to group A beta-hemolytic streptococcal infections
Describe the onset, presentation and cause of PANDAS
- Onset: sudden onset of OCD symptoms or tics after infection with Group-A beta-haemolytic strep
- Presentation: dramatic onset of psychiatric or behavioural problems
- Cause: antibodies ‘cross-react’ with neurons in basal ganglia, causing symptoms
Briefly illustrate how OCD is treated with cognitive behavioural therapy
Cognitive behavioural therapy – exposure response prevention
Describe the pharmacological treatment of OCD
- High dose SSRIs (higher dose + longer treatment course than depression)
- Augmentation with antipsychotics e.g. clomipramine (TCA)
What is PTSD?
- Post-traumatic stress disorder is an anxiety disorder caused by very stressful, frightening or distressing events
- It occurs within 6 months of a traumatic event of exceptional severity
What characterises PTSD?
- Repetitive, intrusive recollection or re-enactment of the event in memories, daytime imagery, or dreams
- Conspicuous emotional detachment, numbing of feeling, and avoidance of stimuli that might arouse recollection of the trauma
Describe the pathophysiology of PTSD
- Hyperactivity of amygdala – causing exaggerated response to perceived threat
- Lower cortisol level – hence, ↓ inhibition of traumatic memory retrieval and sympathetic response
How can PTSD be treated?
- Medical treatment – same as other anxiety disorders
- Cognitive behavioural therapy – Eye Movement Desensitisation Reprocessing (EMDR)
