Panic disorder, autonomic nervous system and dissociation - changes during therapy

OBJECTIVES: Alarming somatic symptoms and in particular the cardiovascular symptoms, are the characteristic features of panic attacks. Increased cardiac mortality and morbidity have been proposed in these patients. Power spectral analysis of electrocardiogram R-R intervals is known to be a particularly successful tool in the detection of autonomic instabilities in various clinical disorders. Heart rate variability (HRV) has been found to be the outcome of rapidly reacting cardiovascular control systems. The aim of our study is to measure very low frequency band (VLF), low frequency band (LF) and high frequency band (HF) components of R-R interval during orthostatic experiment in patients with panic disorder before and after treatment and compares it with healthy controls. METHODS: We assessed heart rate variability in 19 patients with panic disorder before and after 6-weeks treatment with antidepressants combined with cognitive behavioral therapy (CBT) and in 18 healthy controls. Diagnosis was done according to the ICD-10 research diagnostic criteria confirmed with MINI (MINI international neuropsychiatric interview). Patients were treated with CBT and psychotropics. They were regularly every week assessed using CGI (Clinical Global Impression), BAI (Beck Anxiety Inventory) and BDI (Beck Depression Inventory). Heart rate variability was assessed during 3 positions (1st 5 min supine; 2nd 5 min standing; 3rd - 5 min supine) before and after the treatment. Power spectra were computed for very low frequency - VLF (0.0033-0.04 Hz), low-frequency - LF (0.04-0.15 Hz) and high frequency - HF (0.15-0.40 Hz) bands using fast Fourier transformation. RESULTS: Nineteen panic disorder patients resistant to pharmacological treatment entered a 6-week open-label treatment study with combination of SSRI and CBT. The combination of CBT and pharmacotherapy proved to be an effective treatment in these patients. The patients significantly improved during the study period in all rating scales. There were highly statistical significant differences between panic patients and control group in all components of power spectral analysis in 2nd (VLF, LF and H in standing) and in two component of 3rd (LF and HF in supine) positions. There was also a statistically significant difference between these two groups in LF/HF ratio in standing position (2nd). During therapy there was a tendency increasing values in all three positions in components of HRV power spectra, but HF in 1st supine position was the only component where the increase reached the level os statistical significance. CONCLUSIONS: These findings demonstrate a lower autonomic activity in panic disorder patients measured during the changes of postural position in comparison with healthy controls and tendency to increase this autonomic power during the treatment.