|Year : 2014 | Volume
| Issue : 1 | Page : 22-24
A study of parasympathetic function in Manipuri patients with Generalized Anxiety Disorder
Loukrakpam Nataraj Singh1, Yengkhom Govindaraj Singh1, Punyabati Oinam1, Rajkumar Lenin Singh2
1 Department of Physiology, Regional Institute of Medical Sciences, Imphal, Manipur, India
2 Department of Psychiatry, Regional Institute of Medical Sciences, Imphal, Manipur, India
|Date of Web Publication||24-Jun-2014|
Dr. Loukrakpam Nataraj Singh
Department of Physiology, Regional Institute of Medical Sciences, Imphal, Manipur
Source of Support: None, Conflict of Interest: None
Background: Anxiety disorders are becoming a common mental health problem in our society. This could be attributed to the law and order situation, and the socioeconomic problems faced in our social setup. However, very few people are aware of the fact that these disorders, if not treated properly in time, can give rise to major cardiovascular health problems such as myocardial infarction, cardiac arrhythmias, and even coronary heart diseases. Reduction of the cardiac vagal tone (decreased parasympathetic function) is reported as a common associated finding. Objectives: To study involvement of autonomic nervous function, particularly parasympathetic, in Manipuri patients with anxiety disorders. Materials and Methods: Parasympathetic function was tested for 38 patients with anxiety disorders and 30 age- and sex-matched normal healthy subjects (control) by using a battery of three tests, that is:
- Heart rate variability (HRV) to deep and slow breathing (E:I).
- Heart rate response to postural change (30:15).
- Heart rate response to Valsalva maneuver (VR)
Results: The E:I value was significantly low (statistically) in anxiety patients compared to normal healthy subjects indicating reduced parasympathetic function. Conclusion: Patients with anxiety disorders are usually associated with lower cardiac vagal tone (reduced parasympathetic function) making them vulnerable to different cardiovascular disorders such as myocardial infarction, cardiac arrhythmias, and coronary heart diseases.
Keywords: Autonomic nervous system, Generalised anxiety disorder, Heart rate variability
|How to cite this article:|
Singh LN, Singh YG, Oinam P, Singh RL. A study of parasympathetic function in Manipuri patients with Generalized Anxiety Disorder. J Med Soc 2014;28:22-4
|How to cite this URL:|
Singh LN, Singh YG, Oinam P, Singh RL. A study of parasympathetic function in Manipuri patients with Generalized Anxiety Disorder. J Med Soc [serial online] 2014 [cited 2020 Oct 20];28:22-4. Available from: https://www.jmedsoc.org/text.asp?2014/28/1/22/135220
| Introduction|| |
Anxiety disorders are the most prevalent mental disorder in the general population. Approximately one in four adults in the United States has an anxiety disorder at some point in his or her life. Pine et al., describes anxiety as the presence of fear or apprehension that is out of proportion to the context of the life situation. In other words, extreme fear or apprehension is considered clinical anxiety if it is developmentally inappropriate or inappropriate to an individual's life circumstances. 
The term 'anxiety disorders' encompass a group of disorders: Generalized Anxiety Disorder (GAD), panic disorder, agoraphobia, specific phobia, social phobia, obsessive-compulsive disorder (OCD), posttraumatic stress disorder (PTSD), separation anxiety, and acute stress disorder. Anxiety can be conceptualized as a normal and adaptive response to threat that prepares the organism for fight or flight. This preparation is accompanied by increased somatic and autonomic activity controlled by the interaction of the sympathetic nervous system (SNS)and parasympathetic nervous system (PNS). 
Autonomic nervous system (ANS) is an extensive neuronal network innervating every organ in the body for the regulation of homeostatic functions. It modulates the electrical and contractile activity of the myocardium via the interplay of the sympathetic and parasympathetic activity. People with autonomic dysfunction of any cause are at high risk of sudden cardiac death. Various forms of anxiety disorder are associated with autonomic inflexibility (rigidity), that is, mainly characterized by reduced heart rate variability (HRV) and decreased cardiac vagal activity (decreased parasympathetic function). This can result in different cardiovascular diseases which increase the morbidity and mortality rates. 
| Materials and Methods|| |
The study was carried out in the Department of Physiology, Regional Institute of Medical Sciences (RIMS), Imphal during the period September 2009-July 2011 by using a battery of standard and noninvasive autonomic function tests (AFTs). The tests were performed in patients suffering from anxiety disorders and age-matched healthy subjects, which represented the control group after getting approval from the Institutional Ethical Committee (IEC), RIMS. Total of 68 subjects in the age range of 18-50 years were selected for the study, out of which 38 subjects were patients suffering from anxiety disorders and 30 healthy normal subjects of the same age range served as control. Exclusion criteria included chronic and systemic diseases such as diabetes mellitus, habits such as alcoholism or smoking, etc., which will hamper autonomic function.
The patients were sent from psychiatry outpatient department (OPD), RIMS hospital after taking proper history and examination by the consultant psychiatrist. The diagnosis was made as per the guidelines of Pine et al. The study design was a cross-sectional study. AFTs were carried out by using the Polyrite model no. 206, Recorders and Medicare Systems (RMS), Chandigarh.
On the day of the test, no cigarette, nicotine, coffee, food, or drugs per oral or other route were permitted for 3 h prior to the test. The drugs that were disallowed included short acting alpha and beta antagonist, antihistamines, over the counter cough, and cold medication, sympathomimetics and parasympathomimetics. On reaching the department, detailed history of the patients were taken and they were made to rest in a comfortable manner for at least 15 min in the research laboratory room. 
Parasympathetic reactivity was assessed by using a battery of three tests, that is, heart rate response to postural change (30:15 ratio), HRV to deep and slow breathing (E:I), and heart rate response to Valsalva maneuver (VR).  The data were processed statistically by using software Statistical Package for Social Sciences (SPSS) and followed by t-test and chi-square test.
| Results and Observations|| |
The present study is based on the primary data of 67 subjects, out of which 37 are diagnosed as GAD patients and the remaining 30 are age- and sex-matched normal healthy controls. It was carried out in the Department of Physiology, RIMS, Imphal during the period from September 2009 to July 2011. A predesigned pro forma, designed for the purpose was used as a tool for data collection.
From [Table 1], it can be seen that the mean E:I value of the control group is higher than that of the patients. It reveals that the parasympathetic function of patients with GAD is significantly lower (P < 0.05). However, the mean value of 30:15 ratio is comparatively less in patients than in the control group though not significant. The Valsalva ratio mean value of the patients appears to be marginally higher than the control group, though the difference is not statistically significant.
| Discussion|| |
Anxiety disorders are the most prevalent mental disorders in the general population of Manipur. Among the nine disorders comprising 'anxiety disorders', generalized anxiety disorder is the most common. GAD is often accompanied by somatic manifestations that suggest morbid changes in ANS activity, such as rapid heart rate (HR), shortness of breath, sweating, and restlessness.  Thirty-eight subjects (age range, 18-50 years) diagnosed with GAD were enrolled for the study and assessed, but only 37 constituted the study group as one patient's result does not fall within any of the classification criteria. The majority of the subjects was married and was males. A battery of three noninvasive tests to assess parasympathetic reactivity has been deployed for both the patients and control.
In our study, the E:I (HRV during deep and slow breathing) appear to be a more sensitive tool in detecting early autonomic changes than the other parameters. This has also been stated by Wieling et al., (1999) and Ewing et al. The significant difference between E:I levels of cases and control (P < 0.05) and the quantitatively lower values of 30:15, reveal a decrease in parasympathetic function (lower cardiac vagal tone). This finding is similar with the studies of Friedman et al., 1998  and Saric et al., 2004.  Their studies were conducted in adult GAD patients (19-55 years). The findings are suggestive of autonomic rigidity or diminished physiologic flexibility in anxiety disorder patients. This loss of variability in autonomic control system has recently been linked with a number of cardiovascular diseases and dysfunctions, particularly coronary heart diseases, myocardial infarction, and cardiac arrhythmias which can be potentially fatal. 
HRV, the variation in the length of time between consecutive heartbeats, is one measure of PNS activity  and is controlled primarily through the interplay of sympathetic and parasympathetic nervous system (SNS and PNS) activity. A withdrawal of the PNS reduces the flexibility of the cardiovascular system by decreasing HRV, making heart rate more periodic and less variable.  When HRV is reduced, the cardiovascular system becomes more susceptible to electrical instability and sudden death.  Consistent with this idea are findings that the loss of flexibility of the cardiovascular system has been linked with a number of diseases and dysfunctions, including sudden cardiac death, ventricular fibrillation, hypertension, and coronary atherosclerosis.  Excessive cardiovascular reactivity, especially in response to psychological stress is generally thought to be a precursor to many kinds of cardiovascular diseases. Cardiovascular reactivity has been implicated as a direct contributing factor to disease risk and as a marker for disease risk. 
| Conclusion|| |
Anxiety disorders are the most prevalent mental disorder in the general population of Manipur. This could be because of the socioeconomic problems and the law and order situation. Not only do they cause physical and mental distress, they also interfere with the day-to-day life, interpersonal relationship, and also hamper work performance of the individual. Recent research works have found autonomic changes in anxiety patients. Many literatures of repute have explained this on the basis that anxiety is associated with physiological hyperarousal and excessive cardiovascular reactivity.
Among the anxiety disorders, GAD is found to be associated with lower cardiac vagal control (parasympathetic dysfunction) as found in my study. Clinicians can now intervene well in advance and effectively treat the disorder, thereby, preventing the associated morbidities and mortalities.
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