Decreased heart rate Variability during emotion regulation in subject at risk for psychopathology

Simplicio et. AlJournal of Psychological Medicine ©2011

Sam James

Background

1. The parasympathetic and sympathetic nervous system are two divisions of the autonomic nervous system.

2. The sympathetic nervous system is connected with the fight or flight response. (Jansen, 1995) It helps to activate the body from a state of rest. The parasympathetic system is also associated with emotions such as sadness and sexual arousal (there are many more emotions associated with the parasympathetic nervous system).(Kreibig, 2010)

3. The parasympathetic nervous system is connected with bringing someone back to a state of rest. It is always at play in order to maintain homeostasis. (Maickel, 1967)   The sympathetic and parasympathetic nervous do not counter each other, instead they act to regulate each other. The parasympathetic and sympathetic nervous systems connected to various neural pathways that allow it to stimulate muscle movement, such as increasing/decreasing heart rate. (Pomeranz, 1985)

4. Autonomic activity is measured by looking at the Heart Rate Variability (HRV). The HVR is constructed by taking data from an electrocardiograph (ECG). The data is filtered to get rid of any background noise. Afterwards the points are interpolated to get a smoother function.

5. To get data involving the sympathetic and parasympathetic activity time frequency analysis is done to convert the function into a function of time domain. This separates the function into its high and low frequencies. The High Frequency (HF) is an indicator of sympathetic activity while the Low Frequencies (LF) are an indicator of parasympathetic activity.

6. Neuroticism is a personality trait where the person is generally in a negative state. Individuals who suffer from neuroticism are more likely to be suffering emotions such as guilt, anxiety, envy and anger than those who do not suffer from neuroticism. Those who suffer from neuroticism tend to be more shy and self-conscious.

Purpose

1. To determine “whether subjects with high neuroticism present with specific biases in emotion regulation associated with reduced HRV.”

Methods and Materials

1. This study included 44 subjects. These subjects were chosen because of their score on the Eysenck Personality Questionnaire, a test that is used to determine whether suffer suffers from neuroticism or not. The subjects had either high or low scores. Afterwards the subjects were tested for Axis I disorders; these include serious disorders such as schizophrenia and acute depression. Five subjects were excluded because of their history with depression. Another six were later excluded do poor data readings.

2. Subjects were then given questionnaires. These questionnaires were used in part with scales that measured sadness, happiness calmness, anxiety and alertness. After the exclusions a total of 30 subjects were included it the study. 10 of the subjects had high neuroticism scores while the rest had low scores.

3. In this study images were used to illicit emotional reactions. While the subjects viewed the images they were told to either maintain or suppress their emotions.

a. When they were told to maintain their emotions, they were supposed to view the images as they would view them naturally.

b. During the periods when they were told to suppress their emotions they were instructed to decrease the intensity of the emotion that was elicited.

4. The content of the picture of the two conditions (maintain or suppress) were similar. Furthermore it was made sure that viewer felt that the valence and arousal of the images from each set were also similar.

5. 40 images were used in this study. Each picture was shown for five seconds. The subjects saw the images in blocks of five images. Within each block an image of a white cross on a grey background was also presented or one second. The subjects were asked about their experiences with each image. They were asked to give a rating out of four, with four being completely negative. After the subjects had practiced the task ECG data was taken (“pre task recording”).

6. During the task ECG data was taken. The data was sampled at 500 Hz. The peak of the R-wave was determined using a analysis program. An autoregressive (AR) model was used to determine the frequency. AR spectral Analysis was considered better than the Fourier transformation method because this study had only a small sampling signal. This was because the sampling time was limited to the time of each block, which was about 30 seconds. This is alright since the study is looking at the high frequency portion of HRV. Longer times are recommended for the lower frequencies of HRV.

7. Several model orders were tested in order to determine whether the range chosen would be accurate enough. The frequency spectrum used in this study was taken from prior data. The High Frequency portion of the HRV was then calculated by integrating the power within the bandwidth 0.15-0.4Hz, which are the ideal frequencies for the high frequency portion of HRV. The high Frequency and the Low Frequency were also normalized by dividing the two by the power that is above the high frequency range.

Statistical Analysis

1. The data was analyzed using a technique called analyses of variances. Whether the subject had high or low neuroticism was the between subject variable. Where the subject mainted or suppressed his/her emotions was the task condition. While this study generally paid attention to the HF for explanatory purposes the study looked at the LF as well.

Results

1. When the self-assessed were looked at there was a noticeable difference between the low and high neurotic groups. Higher neurotic subjects were generally more anxious. They also reported more symptoms of depression, and hostility. However, there were no noted differences between the methods used by either group.

2. There were no noted differences between the high and low neurotic groups for pre the pre task recording. There was however, a correlation discovered between HRV and group and task. Subjects who had lower neuroticism scores had higher HF values during suppression than during the maintain interval. Subjects who had higher neuroticism scores did not show this increase in HF.

3. No correlation was found for the normalized values of HF and LF. There were no significant correlations found between changes in HF and changes in affect.

Discussion

1. The direct conclusion that was taken from this study was that subjects with high neuroticism score had lower HF when they had to challenge negative emotions. Furthermore, unlike the low scoring patients the high scoring patients did not have an increase in HF during emotional regulation. This data suggests “reduced flexibility in the parasympathetic cardiovascular tone during cognitive regulation of negative emotional stimuli.”

2. The evidence of this study also helps understand that patients with neuroticism are poor with responding to emotions. This idea was shown in Haas et al. 2007, 2008. However, it is further proven by the data from this study.

3. The fact that the neurotic patients in the study had low HF scores suggests that they are not capable of regulating their emotions when facing negative stimuli.

4. The data also hints that there may possibly be correlations between the low frequencies of the HRV. Subjects who had higher neurotic score had a different balance between the low frequencies of the heart rate variability and the high frequencies. This would explain why correlations were found with the High frequency portion that was not normalized.

5. There were also noticeable differences seen in HFn (it was lower in high neurotic patients) but only when off task effects were not included in the analysis. However, there was not enough data to get any true conclusive results.

Conclusion

1. The results from this study was defiantly back up by the results of other studies.

2. It is important to note that this study was limited. It was mostly limited to the fact not enough data was collected. This was a result of the picture stimuli only being shown for thirty seconds. Future studies may incorporate video as a stimuli source. Video stimuli would last longer. This would allow more data to be taken to determine the low frequency aspects of HRV.

3. Another issue was that highly neurotic subjects were shown to have poor emotional regulation. In turn the subjects did not show and of the effects of this other than in the HRV analysis. This does slightly lower the credibility of HRV and whether is reacts to

biases in emotion. Still, a growing amount of literature still suggests that HRV is a reliable method.

Works Cited

Cy, Catherine. "Autonomic Mechanisms of Emotional Reactivity and Regulation." Psychology (2013): n. pag. Web.

Jansen, A. S. P., X. V. Nguyen, V. Karpitskiy, T. C. Mettenleiter, and A. D. Loewy. "Central Command Neurons of the Sympathetic Nervous System: Basis of the Fight-or-Flight Response." Science 270.5236 (1995): 644-46. Print.

Kreibig, Sylvia D. "Autonomic Nervous System Activity in Emotion: A Review." Biological Psychology 84.3 (2010): 394-421. Print.

Maickel, R. P. "THE SYMPATHETIC NERVOUS SYSTEM AS A HOMEOSTATIC MECHANISM. I. ABSOLUTE NEED FOR SYMPATHETIC NERVOUS FUNCTION IN BODY TEMPERATURE MAINTENANCE OF COLD-EXPOSED RATS." The Journal of Pharmacology (1967): n. pag. Print.

Pomeranz, B. "Assessment of Autonomic Function in Humans by Heart Rate Spectral Analysis." Heart and Circulatory Phsyiology (1985): n. pag. Print.

Pottenger, P. M. "Sympathetic and Parasympathetic System Benefits." The Journal of Nervous and Mental Disease 56.5 (1922): 519. Print.

Aysin, Benhur, and Elif Aysin. "Effects of Respiration in Heart Rate Variability Analysis."

(2006): n. pag. Print.

Simplicio, M. Di, G. Costoloni, D. Western, B. Hanson, P. Taggart, and C. J. Harmer. "Decreased Heart Rate Variability during Emotion Regulation in Subjects at Risk for Psychopathology." Psychological Medicine 42.08 (2012): 1775-783. Print.

44 subjects enrolled their

leval of neuroticism measured

The subjects looked at

stimulai while ECG data was

taken

The HRV spectrum was constructed

The data was analyized

using ANOVA