Diffusion tensor imaging (DTI) can be used to examine the structural integrity of regional white matter and to map white matter tracts. DTI studies have been performed in several psychiatric... Show moreDiffusion tensor imaging (DTI) can be used to examine the structural integrity of regional white matter and to map white matter tracts. DTI studies have been performed in several psychiatric disorders, especially in those for which a developmental or a neuropsychiatric component was postulated. Thus far, the use of DTI has been very limited in panic disorder, social anxiety disorder, and generalized anxiety disorder, and somewhat more extensive in post-traumatic stress disorder and obsessive-compulsive disorder. In most anxiety disorders, the results of DTI studies are in line with other structural and functional MRI findings and can be interpreted within the frameworks of existing models for the neurocircuitry of the various disorders. DTI findings could further enrich neurobiological models for anxiety disorders, although replication is often warranted, and studies in pediatric populations are lagging behind remarkably. Show less
We investigated the role of cortisol (an important stress-hormone) in the regulation of social fear and avoidance behavior in socially anxious individuals, which are characterized by extreme fear... Show moreWe investigated the role of cortisol (an important stress-hormone) in the regulation of social fear and avoidance behavior in socially anxious individuals, which are characterized by extreme fear and avoidance of social situations. Previous studies in animals and children showed a relation between increased fearfulness and avoidance and elevated cortisol levels, but the causal role of cortisol in these processes is not known. We found that, only in high socially anxious participants, cortisol administration or stress induction increased avoidance of social threat on an affect-evaluation computer task. Concurrent event-related potentials (brain activity measured with electrodes on the scalp) showed an associated increase in early processing of social threat. Another experiment indicated that the effects of cortisol on early threat processing are task dependent. We conclude that cortisol increases avoidance and facilitates or inhibits early processing of social threat in an adaptive manner, in line with the task goal. This effect is strongest in high anxious individuals, which are particularly sensitive to these threat signals. This knowledge can be relevant for the treatment of SAD, as cortisol levels may increase during exposure therapy, and also because cortisol administration has recently been proposed as a treatment for this disorder. Show less
