11.2 Anxiety disorders Flashcards
Which system primarily mediates the anxiety response?
Primarily by the limbic system which has neural and endocrine targets
What are the neural elements of the stress response (limbic system)?
Hippocampus
Amygdala
Septal area
+/- Prefrontal cortex and Cingulate gyrus
What is the role of the hippocampus in the limbic system?
Receives inputs from many parts of cortex and processes their emotional content
Ultimately projects to thalamus (then back to cortex - Papez Circuit) and also to the hypothalamus causing autonomic responses (hypothalamospinal tract)
Role in memory - Papez circuit may be involved in memory consolidation
What is the role of the Amygdala in the limbic system?
Sits near the tip of the hippocampus
Receives many inputs from the sensory system
Major outputs to the cortex and hypothalamus
Like the hippocampus, involved in the behavioural and autonomic emotional responses
What is the role of the Prefrontal cortex?
Modulation of emotional responses (e.g. consciously suppressing features of anxiety)
‘Perception’ of emotion
What is the connection of the limbic system to the endocrine system?
The limbic system is able to act on the hypothalamus to stimulate the secretion of stress hormones (via the familiar hypothalamo-pituitary-adrenal axis)
Release of cortisol from the adrenal cortex is part of the ‘chronic’ stress response
What are the three stages which occur with prolonged exposure to stressors (cortisol)?
- Alarm reaction - release of adrenaline and cortisol as well as sympathetic activation
- Resistance - chronic stress response - adrenaline wears off but there is prolonged release of cortisol
- Exhaustion - Cannot escape an ongoing stressor - chronic side effects of cortisol start to occur
How can the stress response become pathological?
The stress response can become pathological when you cannot escape a stressor(s) or when ‘trivial’ stressors elicit a strong stress response
What are the symptoms of anxiety?
Palpitations Sweating Trembling or shaking Dry mouth Difficulty breathing Chest pain or discomfort Nausea or abdominal distress Feeling dizzy, unsteady, faint or light headed.
What are the different classifications of anxiety disorders?
Social phobia - anxiety about social situations
Specific phobia’s - e.g. spiders, heights etc…
Generalised anxiety disorder - persistent anxiety about a variety of things
Panic disorder - Recurrent, unexpected panic attacks (severe episodes of acute stress response)
Obsessive compulsive disorder (OCD)
Post-traumatic stress disorder (PTSD)
What is the pathophysiology of anxiety?
GABA levels appear to be low
Low/inappropriate serotonin levels
What is the treatment for anxiety?
Short term benzodiazepines (increase GABA levels)
SSRI’s
(Can also use Pregabalin - GABA analogue)
Cognitive behavioural therapy - patients reflect on thoughts/feelings/behaviours
Social - support groups, charities etc…
What is the epidemiology behind OCD?
1 in 50 people at somepoint
1/3 of cases start between ages 10-15
3/4 started before 30
Equally in males and females
How is OCD characterised?
OCD is primarily characterised by obsessions and compulsions
What is meant by Obsessions when talking about OCD?
Obsessions are thoughts that persist and dominate an invidiuals thoughts despite their awareness that the thoughts are either entirely without purpose, or have persisted and dominated their thinking beyond the point of relevance or usefulness.
They are unpleasant and repugnant, often causing anxiety.
e.g. I might harm my baby OR I might be a paedophile
What is meant by Compulsions when talking about OCD?
Compulsions are motor acts (or sometimes thoughts) that result from an obsession.
Acting out of compulsion may relieve the anxiety provoked by its associated obsession, but frequently carrying out the compulsion is also unpleasant.
e.g. Need to turn the light on or family will die
What is the diagnostic criteria for OCD?
Obsessions and/or compulsions must be present on most days for at least 2 weeks
Obsessions and compulsions have the following features:
- 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 pathophysiology behind OCD?
Unclear but there is some hypothesis:
Basal ganglia re-entrant circuits
Reduced serotonin levels - SSRIs help
Altered activity in range of cortical areas
Autoimmune aetiologies - cross-reactivity with certain streptococcal antigens and the basal ganglia
What is the mechanism behind the re-entrant hypothesis in OCD?
Cortex projects to the basal ganglia and these then project back up to the cortex via the thalamus. This means that obsessional thoughts can re-enter the cortex having entered the basal ganglia.
May be due to overactivity of the direct pathway. Treatments that inhibit thalamic (and hence cortical) activity by reducing the direct pathway or increasing the indirect pathway may hold promise.
What is the treatment of OCD
SSRIs +/- antipsychotics
Deep brain stimulation
CBT and a variety of other interventions
Family support, support groups etc…
What are the features of PTSD?
Can occur within six months following an exceptionally severe traumatic event (e.g. rape, battlefield trauma)
Causes repetitive, intrusive recollection or re-enactment of the event in memories, daytime imagery or dreams.
There is a conspicuous emotional deattachment, numbing of feeling and avoidance of stimuli that might arouse recollection of the trauma
What is the pathophysiology behind PTSD
Unclear however:
Evidence of amygdala hyperactivity causing exaggerated behavioural responses
Low levels of cortisol (normally inhibits traumatic memory retrieval and control sympathetic response)
Treatment for PTSD
SSRIs
Short term benzodiazepines
CBT
Eye movement desensitisation reprocessing therapy
Charities are particularly active such as ‘Help for Heroes’
What are PANDAs and which condition can they be related to?
PANDA = Paediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal infection
Sudden onset of OCD symptoms or tics after infection with group A beta haemolytic strep. Usually 3-12 years.
Antibodies cross-react with neurones in the basal ganglia, causing symptoms.
Responds to treatment with antibiotics and usual OCD treatment.
