Session 11

Question 1

What is the physiological role of anxiety?

Answer 1

The stress response (causing a feeling of anxiety) enables us to escape from
potentially dangerous situations

Question 2

What mediates the stress response?

Answer 2

This response is mediated primarily by the limbic system, which has neural
and endocrine targets

Question 3

Describe the neural elements of the stress response?

Answer 3

Neural elements of the stress response (limbic system)
• Hippocampus
o Receives inputs from many parts of the cortex and
processes their emotional content
o Ultimatelyprojectstothethalamus(andhencebackto
the cortex – the Papez circuit) and also to the hypothalamus (causing autonomic features of emotional responses, since the hypothalamus send projections down through the cord to autonomic preganglionic neurones – the hypothalamospinal tract. This will lead to sympathetic nervous system activation, as well as release of adrenaline from the adrenal medulla – the acute stress response)
o Role in memory – already discussed
 Papez circuit may be involved in memory
consolidation • Amygdala
o Almond shaped structure sitting near the tip of the hippocampus
o Receives many inputs from the sensory system
o Majoroutputstocortexandhypothalamus
o Like the hippocampus, involved in behavioural and
autonomic emotional responses
• Prefrontal cortex (classically not part of the limbic system but
definite roles in emotion)
o Modulation of emotional responses (e.g. consciously
suppressing features of anxiety) o ‘Perception’ of emotion?
• There is a complex interplay between the abovenamed structures

Question 4

Describe the endocrine elements of the stress response?

Answer 4

Endocrine elements of the stress response
• The limbic system is able to act on the hypothalamus to
stimulate the secretion of stress hormones
o Via the familiar hypothalamo-pituitary-adrenal axis

o Release of cortisol from the adrenal cortex is part of the ‘chronic’ stress response

Question 5

What is the general adaptation syndrome?

Answer 5

The general adaptation syndrome refers to three stages that the body goes through during prolonged exposure to stressors
o Stage 1: The alarm reaction
 Release of adrenaline and cortisol as well as sympathetic activation
(described above)
o Stage 2: Resistance (effect of adrenaline starts to wear off)
 Chronic stress response, prolonged release of cortisol
o Stage 3: Exhaustion (when you cannot escape an ongoing stressor)
 Chronic side effects of prolonged cortisol secretion start to occur o The stress response can become pathological when you cannot escape a
stressor(s), or when ‘trivial’ stressors elicit a strong stress response. However, patients with anxiety disorders may go through all of the stages above

Question 6

What is anxiety and it’s symptoms?

Answer 6

Anxiety is the term used for a pathological stress response
o Symptoms – primarily attributable to sympathetic activation
 Palpitations
 Sweating
 Trembling or shaking
 Dry mouth
 Difficulty breathing
 Chest pain or discomfort
 Nausea or abdominal distress (e.g. butterflies in stomach)  Feeling dizzy, unsteady, faint or light-headed

Question 7

How can anxiety disorders be classified?

Answer 7

Classification
 Social phobia
• Anxiety about being in social situations
 Specific phobias
• 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 8

Describe the pathophysiology of anxiety

Answer 8

Pathophysiology
 Unclear
 Equivocal findings in studies of brain activation patterns
 GABA levels appear to be low in some anxiety disorders (maybe
explaining action of benzodiazepines)
 Increasing serotonin levels can help treat anxiety disorders
(mechanism unclear, but hippocampus may be involved)

Question 9

How is anxiety treated?

Answer 9

o Treatment
 Biological
• Short term benzodiazepines
• SSRIs  Psychological
• Cognitive behavioural therapy
o Getting patients to reflect on their
feelings/thoughts/behaviours
Social -
• Support groups, charities etc

Question 10

Describe the epidemiology of OCD

Answer 10

Epidemiology
 Fairly common – 1 in 50 will suffer from it at some point in their lives#  1/3 of cases start between 10 and 15 years of age
 3⁄4 have started by age 30
 Equal prevalence in males and females

Question 11

Describe the characteristics of of OCD

Answer 11

Primarily characterised by obsessions and compulsions
 Obsessions
• Thoughts that persist and dominate an individual’s thinking 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
• Unpleasant and repugnant, often causing anxiety
 Compulsions
• A motor act (or sometimes a thought) resulting from an obsession
• Acting out a compulsion may relieve the anxiety provoked by its
associated obsession, but frequently carrying out the compulsion is
also unpleasant
 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
 Social

• Acknowledged as excessive or unreasonable
• Patient tries to resist, but at least one obsession/compulsion is
unsuccessfully resisted

Question 12

Describe the pathophysiology of OCD

Answer 12

Pathophysiology  Unclear
 Some hypotheses:
• Basal ganglia re-entrant circuits
o The cortex projects to the basal ganglia, and these then project back up to the cortex via the thalamus
o This is an example of a ‘re-entrant’ loop, where obsessional thoughts can re-enter the cortex having entered the basal ganglia
o This may be due to overactivity in the direct pathway o Treatments that inhibit thalamic (and hence cortical) activity by reducing the direct pathway or increasing
the indirect pathway may hold promise (e.g.
subthalamic nucleus stimulation)
• Reduced serotonin levels
o SSRIs help
• Altered activity in a range of cortical areas (cause or effect?)
• Autoimmune aetiologies
o There may be cross-reactivity with certain streptococcal antigens and the basal ganglia

Question 13

What is the treatment for OCD?

Answer 13

Treatment
 Biological
• SSRIs +/- antipsychotics
• Deep brain stimulation?  Psychological
• CBT and variety of other interventions  Social
• Family support
• Groups etc.

Question 14

Describe the features of PTSD?

Answer 14

Features
 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 conspicuous emotional detachment, numbing of feeling, and avoidance of stimuli that might arouse recollection of the trauma

Question 15

Describe the pathophysiology of PTSD

Answer 15

Unclear
• Evidence of amygdala hyperactivity causing exaggerated behavioural responses
• However, low levels of cortisol!

Question 16

What is the treatment for PTSD?

Answer 16

Biological
• SSRIs
• Maybe short term benzodiazepines  Psychological
• CBT
• Eye movement desensitization reprocessing therapy  Social
• Charities are particularly active, such as ‘Help for Heroes’