1. Generalised anxiety symptoms
Generalised anxiety and
autonomic nervous system function
Einars Kupatsa,⁎, Ilja Noviksa, Jelena Vrublevskab, Viktorija Keninaa, Una Kojaloc, Inara Loginaa
aDepartment of Neurology, Riga Stradins University, Latvia
bDepartment of Psychiatry and Narcology, Riga Stradins University, Latvia
cStatistical Unit, Riga Stradins University, Latvia
Introduction
Results
Generalised anxiety disorder (GAD) is a chronic and highly prevalent psychiatric disorder, in which the patient has excessive worry about everyday events and problems. According to a population-based European epidemiological study, over 8.9 million people (1.7%–3.4%) were affected by GAD in 2010, making it one of the most prevalent psychiatric conditions in the European Union. However the pathophysiology of GAD, its role in the autonomic nervous system (ANS) and relationship between GAD and cardiovascular disease are not fully understood. Patients with anxiety are often clinically diagnosed as having somatoform autonomic dysfunction. Somatoform autonomic dysfunction is a poorly defined and un- differentiated sub-diagnosis, which is easy-to-use and does not require instrumental tests. Moreover, somatoform autonomic dysfunction is one the most frequently diagnosed mental disorders in primary care in Latvia. In Latvia, generalised anxiety and autonomic disorders are misunderstood by both patients and medical professionals.
Of the 32 participants with generalised anxiety symptoms, 26 (81%) had autonomic symptoms. Seventeen (53%) patients with generalised anxiety symptoms complained of palpitations and 15 (47%) had dyspnoea. Eight (25%) patients reported fainting and 9 (28%) patients had dizziness. Table 1 shows autonomic metrics for generalised anxiety symptoms and control (non-anxious, healthy volunteers) groups. Table 2 summarises the abnormalities in the generalised anxiety symptoms and control groups. There was no statistically significant association between generalised anxiety symptoms and the prevalence of autonomic abnormalities (Fisher Exact test; p = 0.244).
Table 1. Descriptive statistics for autonomic metrics according to group.
Variable
Controls
Generalised anxiety symptoms
p value
Mean ± SD/median (IQR)
Task Force Monitor
Heart rate
77.5 ( )
74.9 ( )
0.250
LF (Low frequency: Hz)
504.0 ( )
520.5 ( )
0.645
HF (High frequency: Hz)
292 ( )
392.5 ( )
0.322
PSD (Power spectrum density)
( )
( )
0.506
LF/HF ratio
1.5 ( )
1.5 ( )
0.713
30:15 ratio
1.0 ( )
1.1 ( )
0.432
Valsalva ratio
1.8 ( )
1.8 ( )
0.932
ANS Analysis software program
77.75 (± 8,44)
75.02 (± 9.26)
0.870
Alpha1
1.37 (± 0,21)
1.31 (± 0.23)
0.373
SDNN
66.99 (± 23,62)
65.69 (± 21.19)
0.840 SI
52.5 ( )
52.9 ( )
0.721
RMSSD
37.33 (± 13.40)
39.65 (± 15.91)
0.594
Aim of the project
The aim of the study was to determine the prevalence and pattern of cardiovascular autonomic abnormalities in patients with generalised anxiety symptoms by combining two methods: the Ewing test and HRV analysis.
Materials and methods
Thirty-two patients with anxiety symptoms aged more than 18 years were selected from the emergency department of Riga Eastern Clinical University and Paul Stradins Clinical University hospitals. Twenty-three controls were selected from healthy volunteers. The age of participants ranged from 22 to 56 years, with a mean age of ± 8.08 years. Generalised anxiety symptoms were recorded using the 7-item Generalized Anxiety Disorder Scale (GAD-7). Patients from emergency department with a score of 5 and greater were included and formed the anxiety group. Quantitative and clinically validated protocols for the testing of autonomic functions were used. The normal responses in heart rate during the tilt table test were defined as heart rate increment within 10–30 beats per minute and the maximal heart rate less than 120 beats per minute. Normal responses in the blood pressure during the tilt test were defined as a drop of the systolic blood pressure less than 30 mm Hg or drop of the mean blood pressure less than 20 mm Hg. The blood pressure response to tilt testing, heart rate response to deep breathing and the Valsalva manoeuvre were measured using a non-invasive Task Force Monitor (TFM; CN Systems, Graz, Austria). The static grip test was excluded because of its limited sensitivity and poorly established variables. Parasympathetic nervous system (PNS) abnormality was defined if participants had one or more abnormalities in 3 tests: Valsalva ratio, heart rate response to deep breathing, 30:15 ratio. Sympathetic nervous system (SNS) abnormality was defined if participants’ blood pressure response to standing was found to be abnormal. HRV was measured using software programs ANS Analysis and TFM Monitor. RMSSD index was used to assess parasympathetic influences on heart rate. SDNN index was used to assess both sympathetic and parasympathetic influences. Stress index was used to assess sympathetic activity. Non-linear Alpha 1 parameter was used to assess compensation processes and quality of regulation. PSD was used to assess the power distribution as a function of frequency. LF ( Hz) band was used to assess both parasympathetic and sympathetic impulses. HF ( Hz) band was used to assess parasympathetic input to the sinus node. LF/HF ratio was used to express sympathovagal balance and sympathetic modulation. All statistical analyses were performed using SPSS Version 22 (SPSS Inc., Chicago, IL, USA) and Microsoft Excel.
Table 2. Clinical characteristics for the 5 groups of autonomic dysfunction among patients
Characteristics
Normal cardiac autonomic functions (n=33)
Parasympathetic abnormality (n=10)
Sympathetic abnormality (n=1)
Combined PNS and SNS abnormality (n=3)
Borderline cardiac autonomic dysfunction (n=8)
Total
Controls
16 (69,6%) 4
(17,4%)
(0,0%) 3
(13,9%)
23 100%
Generalised anxiety symptoms 17
(53,1%) 6
(18,8%) 1
(3,1%)
3 (9,4%)
5 (15,6%)
32 100%
Conclusion
While patients with generalised anxiety symptoms often describe autonomic arousal symptoms, the prevalence of autonomic dysfunction as confirmed by abnormal cardiovascular responses to Ewing battery testing does not differ between participants with generalised anxiety symptoms and healthy subjects. This difference between subjective self-report and actual physiological state can be explained by psychological factors and distorted perception. Education of general practitioners in this field should be seriously considered to reduce diagnostic errors and avoid incorrect treatment strategies.