Increased vagal tone has been associated with treatment success
using pharmacological agents and cognitive-behavioral treatment
in major depression, but not using electroconvulsive therapy.
The present study investigated whether increases in vagal tone
would be associated with favorable treatment response with
nonpharmacological treatment. At baseline and following treatment,
16 subjects were administered the Hamilton Rating Scale for
Depression (HRSD) followed by electrocardiographic recording.
Those with little change in vagal tone from before to after
treatment showed minimal reduction in HRSD score (−4.8);
those with larger vagal tone change showed a large decrease
in HRSD score (−14.8). Changes in vagal tone are thus
related to favorable treatment response in depression, and do
not represent anticholinergic pharmacological effects. Future
work manipulating vagal tone might prove informative in teasing
apart the causal role of vagal tone and depression.