Does hyperventilation change the cortical hemodynamics of panic disorder? Functional Near-Infrared Spectroscopy (fNIRS) based case-control study

INTRODUCTION: Hyperventilation has been considered as a cause, correlate and consequence of panic attacks. Till date, we don’t have any studies on the effects of hyperventilation in the cortical hemodynamic activation in patients with panic disorder (PD). OBJECTIVES: To explore the change in neuro-hemodynamics of cortical activity in panic disorder after hyperventilation using fNIRS. METHODOLOGY: It was a hospital based cross-sectional case-control study conducted at a tertiary health centre. Cortical activity during n-Back task before and after voluntary hyperventilation (symptom provocation) was assessed using fNIRS (functional near-infrared spectroscopy) in 21 drug-naïve PD patients and compared with healthy controls (HC). RESULTS: Panic disorder group performed poorer in 2-back task compared to healthy controls after hyperventilation. Post hyperventilation, PD group had significantly lesser HbO activation during 2-back in right PFC (BA46) compared to HC. HC group had significantly lesser HbO activation during 0-back in left PFC (BA10) compared to PD group. However, there was no significant difference in HbR between the groups. DISCUSSION: This is the first of its kind study to understand the influence of hyperventilation on the hemodynamic activity during executive function tasks. The above findings suggest differential activation of different areas in PFC between groups. Also, the activation patterns differ significantly after symptom provocation by hyperventilation.