background There is evidence that the autonomic nervous system (ans) plays a role in the pathophysiology of depression, but is also strongly influenced by antidepressants. Recently, salivary alpha-amylase (saa) has been proposed as an alternative to reflect ans activity.
aim We investigated ans activity, as measure using saa, in patients with a major depressive disorder (mdd) compared to healthy controls. Furthermore, we studied effects of antidepressants on saa.
methods Data are from the Netherlands Study of Depression and Anxiety (nesda), a large cohort study on the course of depressive and anxiety disorders. Three comparison groups were formed: control participants (n = 329), participants with remitted mdd (n = 611), and patients with current mdd (n = 752) according to dsm-iv classification. Alpha-amylase in saliva was acquired at two points in time in the late evening (i.e. at 22:00h and 23:00h).
results In comparison to patients without antidepressants, users of tricyclic antidepressants (tcas) showed significantly higher saa levels (p = 0.01). A trend towards significance (p = 0.06) was found with higher saa levels in patients with current mdd compared to controls (p = 0.06).
conclusion The findings suggest that increased autonomic activity, leading to higher saa levels, in depressed patients might not be intrinsic effects of depression per se, but may be an effect induced by tcas that are prescribed to a substantial part of patients with these disorders.