17. Anxiety Flashcards
(36 cards)
Define anxiety.
A feeling of worry, nervousness, or unease about something with an uncertain outcome
What is the physiological role of stress?
The stress response (causing a feeling of anxiety) enables us to escape from potentially dangerous situations
What is the anxiety response mediated by?
Mediated primarily by the limbic system, which has neural and endocrine target
What are the 2 elements of the stress response?
Neural elements and endocrine elements
What are the neural elements of the stress response?
- Hippocampus
- Amygdala
- Prefrontal cortex (classically not part of the limbic system butdefinite roles in emotion)
what is the role of the hippocampus in the stress response?
o Receives inputs from many parts of the cortex and
processes their emotional content
o projects to the thalamus(and back to the cortex – the Papez circuit) and also to the hypothalamus
o Role in memory
- Papez circuit may be involved in memory
consolidation
o role in expression of emotion
what is the effect of the hippocampus projecting to the hypothalamus?
causes 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
role of amygdala?
o Almond shaped structure sitting near the tip of the hippocampus
o Receives many inputs from the sensory system
o Major outputs to cortex and hypothalamus
o Like the hippocampus, involved in behavioural and
autonomic emotional responses
what are the 3 parts of the hypothalamus?
subiculum, hippocampus proper, dentate gyrus
what is the role of the Prefrontal cortex?
o Modulation of emotional responses (e.g. consciously
suppressing features of anxiety)
o ‘Perception’ of emotion?
what is the role of the Prefrontal cortex and Anterior cingulate gyrus in the limbic system?
Both have modulatory effect on processes associated with the hypothalamus
What are the endocrine elements of the stress response?
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 two ways in which the hypothalamus induced the stress response?
- activates sympathetic nervous system
- activates glands and smooth muscle
- activates adrenal medulla to release adrenaline and noradrenaline - activates adrenal cortical system by releasing CRF, pituitary gland releases ACTH and induces adrenal cortex to release steroid hormones
what are the names of the two parts of the stress response?
- limbic system
2. limbic-hypothalamo-pituitary- adrenal axis
What does the general adaptation syndrome refer to?
Refers to three stages that the body goes through during prolonged exposure to stressor
What are the 3 stages of the general adaptation syndrome?
Stage 1: The alarm reaction
- Release of adrenaline and cortisol as well as sympathetic activation
Stage 2: Resistance (effect of adrenaline starts to wear off)
- Chronic stress response, prolonged release of cortisol
Stage 3: Exhaustion (when you cannot escape an ongoing stressor)
- Chronic side effects of prolonged cortisol secretion start to occur
When does the stress response 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 (e.g. butterflies in stomach)
- Feeling dizzy, unsteady, faint or light-headed
What are the different classifications of anxiety disorders?
- 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)
What is the pathophysiology of anxiety disorders and what appears to help?
- unclear
- GABA appears to be low in some (panic disorder)
- increasing serotonin can help (mechanism unclear)
what are the chronic side effects of prolonged cortisol secretion?
muscle wastage
suppression of immune system
hyperglycaemia
What is the biological treatment for anxiety disorders?
- Mainstay is SSRIs
- Short term benzodiazepines (addictive)
- Can use pregabalin - a GABA analogue
describe how benzodiazepines can help anxiety disorders?
- GABA is the main inhibitory neurotransmitter
- GABA levels are decreased in cortex in patients with panic disorder quickly
- Benzodiazepines increase GABA transmission so reduce anxiety
describe how SSRIs can help anxiety disorders?
- Increased levels of serotonin (due to SSRIs) may stimulate serotonin receptors in hippocampus
- Leads to neuroprotection, neurogenesis and reduction of anxiety
