Scientists dont really know for sure that the changes in the brain is the CAUSE of social anxiety or the EFFECT of social anxiety and the reason is that in various studies significant brain changes have been observed in people treated with THERAPY alone, just as observed in people treated with medication. Bio amine theory has got more to do with our understanding of how the brain works and that understanding is very limited.
Scientists dont know for fact how the antidepressants work, but because it is proven to be better than a PLACEBO in most clinical trials it is accepted in the medical community as a treatement, remember most such clinical trials are some how done by people eager to prove the bio amine theory hence the studies are inconclusive so we should not jump to conclusions.
a more rational, unbiased and multi dimentional research is required which considers both neurotransmitters theory as well as the psychological theory to get a better understanding of the mental health problems such as social anxiety disorder, depression and all.
But experience has shown that not all people respond well to a particular approach so some times medications can be life saving and in some cases therapy, and ya irrespective of the competition among medicine and therapy one thing is known for fact that the gains made with the help of therapy last LONGER as compared to medicine, medicine only works as long as one is taking it and also we should also consider the side effects, this idea is supported by significant studies.
We can change the feelings and sensations with the help of medication but how can we change the underlying beliefs and dysfunctional assumption, the mind set, the mental change is completely a psychological process even if it is supplemented by medicine.