Background: Panic Disorder (PD) is a heterogeneous disease and panic attacks are divided according to the different symptom clusters as respiratory, nocturnal, nonfearful, cognitive, and vestibular subtypes. Oxidative stress (OS) is produced by free radicals which are named as reactive oxygen species (ROS). They can be evaluated indirectly by measurement of some antioxidant enzyme levels such as superoxide dismutase (SOD), catalase (CAT), or glutathione peroxidase (GSH-Px). PD is known to be associated with a high frequency of comorbid immunological and increased expression of T lymphocytes compared to controls. Adenosine deaminase (ADA) has been accepted as an important enzyme in the maturation and function of T lymphocytes. The aetiology of panic disorder is yet to be fully understood. There is mounting evidence indicating that ROS may have an important role in the pathogenesis of PD.
Objective: In the present study we aimed to compare SOD, GSH-Px, and ADA activities in panic disorder patients with/without nocturnal, respiratory subytypes, and healthy subjects. Thus to evaluate the effects of OS and inşammatory process on pathogenesis of PD and to determine biological parameters in the subtypes of PD.
Methods: The study comprised of 60 patients with PD and 30 healthy control subjects. Panic Attack Symptom Checklist (PASC), Panic and Agoraphobia Scale (PAS), Hamilton Depression Rating Scale (HAM-D), and Hamilton Anxiety Rating Scale (HAM-A) were administered to the patients. A nocturnal panic attack is defined as an abrupt waking from sleep in a state of panic attack. The respiratory subtype is four of the following five symptom criteria during an individual's most recent severe panic attack: Feeling of choking or smothering sensations; shortness of breath; chest pain or discomfort; numbness or tingling sensations; and fear of dying. The nonrespiratory subtype is operationalized as that which does not meet the mentioned symptom criteria. The biochemical analyses were made after all the blood samples were collected. The laboratory analyses of investigation were conducted in Department of Medical Biology, Faculty of Medicine, at the University of Yuzuncu Yil.
Results: We found that SOD and GSH-Px blood activities of patients were significantly lower, and ADA activities of patients were higher than the healthy controls. All of the activities were not significantly different between respiratory and nocturnal subtypes. There were no significant relationships between the duration of illness and Panic-Agoraphobia (PAS) scores of patients with nocturnal subtypes. Hamilton Depression Rating Scale (HAM-D) and Hamilton Anxiety Rating Scale (HAM-A) scores of the patients with nocturnal subtype were significantly higher than the patients without nocturnal subtype. When examining the correlations between these variables and enzyme levels, there was only a positive correlation between duration of disease and serum activities of GSH-Px.
Conclusion: In conclusion, SOD and GSH-Px ADA activities of the patients with PD are different from healthy subjects. Our results suggest that oxidative and inşammatory processes may play role in pathophysiology of PD. These findings may support the idea that both nocturnal and respiratory subtypes of PD have different symptom clusters of the same disease.