11.2 Anxiety disorders

Question 1

Which system primarily mediates the anxiety response?

Answer 1

Primarily by the limbic system which has neural and endocrine targets

Question 2

What are the neural elements of the stress response (limbic system)?

Answer 2

Hippocampus
Amygdala
Septal area
+/- Prefrontal cortex and Cingulate gyrus

Question 3

What is the role of the hippocampus in the limbic system?

Answer 3

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

Question 4

What is the role of the Amygdala in the limbic system?

Answer 4

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

Question 5

What is the role of the Prefrontal cortex?

Answer 5

Modulation of emotional responses (e.g. consciously suppressing features of anxiety)
‘Perception’ of emotion

Question 6

What is the connection of the limbic system to the endocrine system?

Answer 6

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

Question 7

What are the three stages which occur with prolonged exposure to stressors (cortisol)?

Answer 7

1. Alarm reaction - release of adrenaline and cortisol as well as sympathetic activation
2. Resistance - chronic stress response - adrenaline wears off but there is prolonged release of cortisol
3. Exhaustion - Cannot escape an ongoing stressor - chronic side effects of cortisol start to occur

Question 8

How can the stress response become pathological?

Answer 8

The stress response can become pathological when you cannot escape a stressor(s) or when ‘trivial’ stressors elicit a strong stress response

Question 9

What are the symptoms of anxiety?

Answer 9

Palpitations
Sweating
Trembling or shaking
Dry mouth
Difficulty breathing
Chest pain or discomfort
Nausea or abdominal distress
Feeling dizzy, unsteady, faint or light headed.

Question 10

What are the different classifications of anxiety disorders?

Answer 10

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)

Question 11

What is the pathophysiology of anxiety?

Answer 11

GABA levels appear to be low

Low/inappropriate serotonin levels

Question 12

What is the treatment for anxiety?

Answer 12

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…

Question 13

What is the epidemiology behind OCD?

Answer 13

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

Question 14

How is OCD characterised?

Answer 14

OCD is primarily characterised by obsessions and compulsions

Question 15

What is meant by Obsessions when talking about OCD?

Answer 15

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

Question 16

What is meant by Compulsions when talking about OCD?

Answer 16

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

Question 17

What is the diagnostic criteria for OCD?

Answer 17

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.

Question 18

What is the pathophysiology behind OCD?

Answer 18

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

Question 19

What is the mechanism behind the re-entrant hypothesis in OCD?

Answer 19

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.

Question 20

What is the treatment of OCD

Answer 20

SSRIs +/- antipsychotics
Deep brain stimulation

CBT and a variety of other interventions

Family support, support groups etc…

Question 21

What are the features of PTSD?

Answer 21

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

Question 22

What is the pathophysiology behind PTSD

Answer 22

Unclear however:
Evidence of amygdala hyperactivity causing exaggerated behavioural responses

Low levels of cortisol (normally inhibits traumatic memory retrieval and control sympathetic response)

Question 23

Treatment for PTSD

Answer 23

SSRIs
Short term benzodiazepines

CBT
Eye movement desensitisation reprocessing therapy

Charities are particularly active such as ‘Help for Heroes’

Question 24

What are PANDAs and which condition can they be related to?

Answer 24

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.

Question 25

How does the basal ganglia normally work and what is believed to happen in re-entrance circuits?

Answer 25

Normally get an INPUT from the cortex and subcortical areas
This input is PROCESSED by the basal ganglia (namely by the striatum)
The OUTPUT of the basal ganglia is throught the thalamus which has inhibitory fibres via GABA-ergic neurons
In OCD there is a lack of the inhibitory fibres therefore get a re-entry from the thalamus to the cortex.