[imark3000]

http://pmj.bmj.com/content/77/904/89.full
This is a comprehensive article, easy to read and covering many topics which were discussed on this forum such as the influence of noradrenaline, serotonin and Gaba neurotransmitters systems on PD.
"Abstract
There has been a recent surge of interest in the subject of anxiety in patients with Parkinson's disease. Up to 40% of patients with Parkinson's disease experience clinically significant anxiety. This anxiety may be a psychological reaction to the stress of the illness or may be related to the neurochemical changes of the disease itself. Antiparkinsonian drugs may have a role in the pathogenesis of the anxiety. The anxiety disorders in Parkinson's disease patients appear to be clustered in the panic disorder, phobic disorder, and generalised anxiety disorder areas. The degree of comorbidity between anxiety and depression in patients with Parkinson's disease is in excess of that found in patients without the disease and anxiety in combination with depression may represent a specific depressive subtype in Parkinson's disease. As yet, there is no trial evidence as to the treatment of anxiety in patients with Parkinson's disease.