Cardiac Coherence and Posttraumatic Stress Disorder in Combat Veterans

Background  • The  need  for  treatment  of  posttraumatic stress  disorder  (PTSD)  among  combat  veterans  returning from Afghanistan and Iraq is a growing concern. PTSD has been associated with reduced cardiac coherence (an indicator of heart rate variability [HRV]) and deficits in early stage information  processing  (attention  and  immediate  memory) in different studies. However, the co-occurrence of reduced coherence and cognition in combat veterans with PTSD has not been studied before. Primary Study Objective • A  pilot  study  was  undertaken  to assess the covariance of coherence and information processing in combat veterans. An additional study goal was assessment of effects of HRV biofeedback (HRVb) on coherence and information processing in these veterans.  Methods/Design • A two-group (combat veterans with and without PTSD), pre-post study of coherence and information processing was employed with baseline psychometric covariates. Setting  • The  study  was  conducted  at  a  VA medical  Center outpatient mental health clinic.Participants • Five combat veterans from Iraq or Afghanistan with PTSD and five active-duty soldiers with comparable combat exposure who were without PTSD.Intervention  • Participants  met  with  an  HRVb  professional once weekly for 4 weeks and received visual feedback in HRV patterns while receiving training in resonance frequency breath-ing and positive emotion induction. Primary Outcome Measures • Cardiac  coherence,  word  list learning, commissions (false alarms) in go–no go reaction time, digits backward. Results • Cardiac coherence was achieved in all participants, and the increase in coherence ratio was significant post-HRVb training. Significant improvements in the information processing indicators were achieved. Degree of increase in coherence was the likely mediator of cognitive improvement.  Conclusion • Cardiac coherence is an index of strength of control  of  parasympathetic  cardiac deceleration in an individual that has cardinal importance for the individual’s attention and affect regulation.

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