Anxiety

Question 1

What does the limbic system do

Answer 1

Involved in emotion, memory and arousal

Question 2

What does the hippocampus, amygdala, and cingulate gyrus do

Answer 2

• Hippocampus - located in the medial inferior area of temporal lobe
  
  • Involved in memory and expressions of emotion
• Amygdala - located in the roof of lateral ventricle
  
  • Collection of nuclei
  • Drive related behaviours (decision making) and processing of associated emotions
• Cingulate gyrus
  - Has modulatory effect on processes associated with the hypothalamus and processes emotions and behaviour regulation

Question 3

What structures do the limbic structures interact with

Answer 3

• Cortex sends and receives signals from the limbic structures
• Limbic structures send signals to hypothalamus, which regulates motor regions and sympathetic nervous system
  - When running away from something, motor regions induce leg movement and sympathetic nervous system releases adrenaline to increase heart rate and force of contraction

Question 4

Describe the limbic-hypothalamo-pituitary-adrenal axis

Answer 4

• Limbic structures stimulate hypothalamus to produce CRH, which causes pituitary gland to produce ACTH leading to increased cortisol secretion
• Cortisol acts to:
  
  • Increase energy metabolite levels
  • Suppression of immune system
  • Inhibition of allergic and inflammatory processes
• Cortisol acts to maintain response to stress - longer action time than adrenaline from sympathetic nervous system
• Prolonged stress causes exhaustion (continued cortisol secretion), leading to muscle wastage, suppression of immune system and hyperglycaemia

Question 5

Define anxiety

Answer 5

A feeling of worry, nervousness, or unease about something with an uncertain outcome

Question 6

List the symptoms of anxiety

Answer 6

• Palpitation
• Sweating
• Trembling/shaking
• Dry mouth
• Difficulty breathing
• Chest pain or discomfort
• Nausea or abdominal distress (butterflies in stomach)
• Feeling fizzy, unsteady, faint or light-headed

Question 7

Describe possible pathophysiology of anxiety

Answer 7

• GABA is the main inhibitory neurotransmitter
  
  • GABA levels are decreased in cortex in patients with panic disorder
  • Benzodiazepines increase GABA transmission so reduce anxiety - enhance GABA binding

Question 8

Describe the treatment of anxiety

Answer 8

• Increased levels of serotonin (selective serotonin reuptake inhibitors) may stimulate serotonin receptors in hippocampus
  - Leads to neuroprotection, neurogenesis and reduction of anxiety
• Cognitive behavioural therapy - help identify and face emotions, behaviour, reactions, thoughts
• Pregabalin (GABA analogue) - expensive and more side effects than SSRI
  
  • Do not use benzodiazepines long term - addictive and dangerous in overdose

Question 9

Define obsessions

Answer 9

• A thought that persists and dominants 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 of usefulness
  
  • Often causes anxiety and guilt - unpleasant
• Eg. A new mother thinking ‘I might harm my baby’

Question 10

Define compulsions

Answer 10

• Obsessional motor acts
• May result from an obsessional impulse that leads directly to the action, or they may be mediated by an obsessional mental image or fear

Question 11

Describe the diagnostic criteria for OCD

Answer 11

• Obsessions/compulsions present on most days for a period of at least 2 weeks
• Originate in the mind of the patient
• Repetitive and unpleasant - must cause distress or interfere with the patient’s social or individual functioning
• Acknowledge as excessive or unreasonable - psychosis is when no acknowledgement made
• Patients tries to resist, but at least one obsession/compulsion is unsuccessfully resisted

Question 12

Describe possible pathophysiology of OCD

Answer 12

• Re-entry circuits in basal ganglia - recycling of ideas causing person to become doubtful and therefore perform action again
  
  • Idea recycles between cortex and basal ganglia where the motor action output from the basal ganglia goes to the cortex and then re-enters back to the basal ganglia
• Reduced serotonin
• PANDAS - paediatric autoimmune neuropsychiatric disorder associated with streptococcal infection
  
  • Sudden onset of OCT symptoms or tics after streptococcal infection
  • Antibodies react with neurons in basal ganglia, causing symptoms

Question 13

Describe the treatment of OCD

Answer 13

• Cognitive behavioural therapy
• Exposure response prevention - allow patient to face their worries
  
  • Prevent the recycling of ideas/compulsion
• High dose SSRIs - higher dose and longer treatment (3 months) than in depression
• Clomipramine - tricyclic antidepressant
• Deep brain stimulation - stimulation of subthalamic nucleus enhances stimulatory signals to GPi, which increases inhibitory signals to the thalamus and thus reduces output (motor actions) to cortex

Question 14

Define post traumatic stress disorder (PTSD)

Answer 14

• Within 6 months of traumatic event of exceptional severity
• Repetitive, intrusive recollection or re-enactment of the event in memories, daytime imagery or dreams

Question 15

Describe the pathophysiology of PTSD

Answer 15

• Hyperactivity of amygdala causing exaggerated response to perceived threat
• Cortisol inhibits traumatic memory retrieval and controls sympathetic response
  - In PTSD, cortisol levels low

Question 16

Describe the treatment of PTSD

Answer 16

• Medical treatment same as other anxiety disorders
• Eye movement desensitisation reprocessing (EMDR) - distracts the brain when PTSD thoughts occur to attempt to store in an isolated memory network