Anxiety
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Clinic
- Anxiety is an entity which contain sign/symptoms such as Uneasiness / Worry/ Palpitation / Hyper hydrosis / Mouth dryness
- Its underlying mechanism is Sympathetic hyperactivity.
Anxiety vs. Fear
- Both are symptoms, differentiating from their qualities as below.
| Four main domains | Fear | Anxiety |
|---|---|---|
| Duration of emotional experience | Short | Long |
| Temporal focus | Present | Futute |
| Specificity of the threat | Specific | Diffuse |
| Motivated direction | Escape | Additional associated cognitive activity |
Neuroanatomy
- Amygdala (which regulates emotions like anxiety and fear, stimulating the HPA axis and sympathetic nervous system). People who have anxiety tend to show high activity in response to emotional stimuli in the amygdala. Some writers believe that excessive anxiety can lead to an overpotentiation of the limbic system (which includes the amygdala and nucleus accumbens), giving increased future anxiety, but this does not appear to have been proven.
- Hippocampus (which is implicated in emotional memory along with the amygdala)
- Research upon adolescents who as infants had been highly apprehensive, vigilant, and fearful finds that their nucleus accumbens is more sensitive than that in other people when deciding to make an action that determined whether they received a reward. This suggests a link between circuits responsible for fear and also reward in anxious people. As researchers note, "a sense of 'responsibility', or self-agency, in a context of uncertainty (probabilistic outcomes) drives the neural system underlying appetitive motivation (i.e., nucleus accumbens) more strongly in temperamentally inhibited than noninhibited adolescents".
The gut-brain axis
- The microbes of the gut can connect with the brain to affect anxiety. Gut microbes such as Bifidobacterium and Bacillus produce GABA and dopamine, respectively.
- Another key pathway is HPA axis. The microbes can control the levels of cytokines in the body, and altering cytokine levels creates direct effects on areas of the brain such as the hypothalamus, the area that triggers HPA axis activity.
- HPA axis regulates production of cortisol. When HPA activity spikes, cortisol levels increase, processing and reducing anxiety in stressful situations.