There are many studies investigating neural bases of<unk> . Although the exact neural mechanisms have not been found yet, there is evidence relating<unk>  to imbalance in some neurochemicals and hyperactivity in some brain areas. Neurotransmitters<unk> ility is closely tied to dopaminergic neurotransmission. In a 2011 study, a direct relation between<unk>  status of volunteers and binding affinity of dopamine D2/3 receptors in the striatum was found. Other research shows that the binding affinity of dopamine D2 receptors in the striatum of<unk>  anxiety sufferers is lower than in controls. Some other research shows an abnormality in dopamine transporter density in the striatum of<unk>  anxiety sufferers. However, some researchers have been unable to replicate previous findings of evidence of dopamine abnormality in<unk> . Studies have shown high prevalence of<unk>  anxiety in Parkinson's disease and schizophrenia. In a recent study,<unk>  phobia was diagnosed in 50% of Parkinson's disease patients. Other researchers have found<unk>  phobia symptoms in patients treated with dopamine antagonists like haloperidol, emphasizing the role of dopamine neurotransmission in<unk> . Some evidence points to the possibility that<unk>  involves reduced serotonin receptor binding. A recent study reports increased serotonin transporter binding in psychotropic medication-naive patients with generalized<unk> . Although there is little evidence of abnormality in serotonin neurotransmission, the limited efficacy of medications which affect serotonin levels may indicate the role of this pathway. Paroxetine, sertraline and fluvoxamine are three SSRIs that have been approved by the FDA to treat<unk> . Some researchers believe that SSRIs decrease the activity of the amygdala. There is also increasing focus on other candidate transmitters, e.g. norepinephrine and glutamate, which may be over-active in<unk> , and the inhibitory transmitter GABA, which may be under-active in the thalamus. Brain areas The amygdala is part of the limbic system which is related to fear cognition and emotional learning. Individuals with<unk>  have been found to have a hypersensitive amygdala; for example in relation to<unk>  threat cues (e.g. perceived negative evaluation by another person), angry or hostile faces, and while waiting to give a speech. Recent research has also indicated that another area of the brain, the anterior cingulate cortex, which was already known to be involved in the experience of physical pain, also appears to be involved in the experience of<unk>  pain', for example perceiving group exclusion. Recent research also highlighted the potent role of the prefrontal cortex, especially its dorsolateral part, in the maintenance of cognitive biases involved in<unk> . A 2007 meta-analysis also found that individuals with<unk>  anxiety had hyperactivation in the amygdala and insula areas which are frequently associated with fear and negative emotional processing.
Social anxiety disorder
Avoidant personality disorder
Separation anxiety disorder
Schizotypal personality disorder  Schizotypal disorder  1
Generalized anxiety disorder
Blood phobia
Body dysmorphic disorder
Somatization disorder