Previous research suggests that heart rate variability (HRV) biofeedback aimed at increasing HRV can reduce anxiety and stress. However, some mental quiescence practices that reduce HRV during the practice sessions also lead to positive emotional outcomes. Thus, it is not obvious that the benefits of HRV-biofeedback accrue due to increasing HRV during the session. An alternative possibility is that the benefits arise from engaging prefrontal control over heart rate. In this study, the investigators will test two possible mechanisms of the effects of HRV on emotional health by comparing two groups. In one group, participants will be asked to engage in daily training to decrease HRV using the HRV biofeedback device. In the other group, participants will be asked to engage in daily training to increase HRV using the HRV biofeedback device. This will allow analyses to pit two possible mechanisms against each other: 1. Mechanism 1: engaging prefrontal control over heart rate is the critical factor that allows HRV biofeedback to help improve well-being. In this case, well-being should increase over time in both groups, as both training should engage prefrontal cortex to implement self-directed control over heart rate. Strengthening prefrontal control mechanisms may help improve emotion regulation in everyday life. 2. Mechanism 2: increased HRV during the training sessions leads to greater functional connectivity among brain regions associated with emotion regulation during the high HRV state. In this case, improved well-being would be specifically associated with having time each day during which there were very high HRV states, and so improved well-being should be seen only in the group in which participants get biofeedback to increase HRV.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
193
Participants will be asked to undergo daily practice to regulate (either increase or decrease) HRV for 5 weeks.
University of Southern California
Los Angeles, California, United States
mPFC-right Amygdala Resting-state Functional Connectivity for Younger Adults (ANOVA)
The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the right amygdala. Higher values indicate greater connectivity.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
mPFC-right Amygdala Resting-state Functional Connectivity for Older Adults (ANOVA)
The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the right amygdala. Higher values indicate greater connectivity.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
mPFC-right Amygdala Resting-state Functional Connectivity for Younger Adults (Post-Pre)
The strength of resting-state functional connectivity between mPFC and the right amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
mPFC-right Amygdala Resting-state Functional Connectivity for Older Adults (Post-Pre)
The strength of resting-state functional connectivity between mPFC and the right amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Emotion Regulation in Younger Adults (Behavior)
Emotional intensity ratings, which participants reported during the emotion regulation task inside MRI scanner before and after intervention. The ratings ranged from 1 through 4, and 4 represents strongest intensity.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Emotion Regulation in Older Adults (Behavior)
Emotional intensity ratings, which participants reported during the emotion regulation task inside MRI scanner before and after intervention. The ratings ranged from 1 through 4, and 4 represents strongest intensity.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Left Amygdala BOLD Activity During Emotion Regulation in Younger Adults
We measured percent changes (%) in BOLD activity in the left amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Left Amygdala BOLD Activity During Emotion Regulation in Older Adults
We measured percent changes (%) in BOLD activity in the left amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Right Amygdala BOLD Activity During Emotion Regulation in Younger Adults
We measured percent changes (%) in BOLD activity in the right amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Right Amygdala BOLD Activity During Emotion Regulation in Older Adults
We measured percent changes (%) in BOLD activity in the right amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Decision-making for Younger Adults at Post Intervention (Behavior)
The decision-making ability was measured by multiple-choice responses during a computer-based task. Median percentage of acceptance of unfair offers and fair offers were calculated. A higher percentage of accepted both unfair and fair offers points toward more rational decision-making and likely better emotion regulation. This task was administered only at post-intervention (but not pre-intervention).
Time frame: one time point: at study completion, which is the end of 5-week training
Decision-making for Younger Adults (fMRI)
We measured percent changes (%) in BOLD activity in the dorsal anterior cingulate cortex and anterior insula during a computer-based decision-making task. Higher values indicate greater activity.
Time frame: one time point: at study completion, which is the end of 5-week training
Mood for Younger Adults
Emotional well-being measured by the Profile of Mood States (POMS) for younger adults. The POMS consists of 40 items that are rated on a 5-point scale ranging from "0=not at all" to "4=extremely. Total Mood Disturbance (TMD) was calculated by summing the totals for the negative items and then subtracting the totals for the positive items. A constant (i.e., 100) was added to the TMD formula in order to eliminate negative scores. Higher scores indicate more negative mood states. The scores range from 56 and 216.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Mood for Older Adults
Emotional well-being measured by the Profile of Mood States (POMS) for older adults. The POMS consists of 40 items that are rated on a 5-point scale ranging from "0=not at all" to "4=extremely. Total Mood Disturbance (TMD) was calculated by summing the totals for the negative items and then subtracting the totals for the positive items. A constant (i.e., 100) was added to the TMD formula in order to eliminate negative scores. Higher scores indicate more negative mood states. The scores range from 56 and 216.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Depression for Younger Adults
Emotional well-being measured by the Center for Epidemiological Studies Depression Scale (CES-D) for younger adults. The CES-D consists of 20 items that are rated on a scale of 0 to 3 (0 = Rarely or None of the Time, 1 = Some or Little of the Time, 2 = Moderately or Much of the time, 3 = Most or Almost All the Time). Possible range of scores is 0 to 60, with the higher scores indicating more depressive symptoms.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Depression for Older Adults
Emotional well-being measured by the Center for Epidemiological Studies Depression Scale (CES-D) for older adults. The CES-D consists of 20 items that are rated on a scale of 0 to 3 (0 = Rarely or None of the Time, 1 = Some or Little of the Time, 2 = Moderately or Much of the time, 3 = Most or Almost All the Time). Possible range of scores is 0 to 60, with the higher scores indicating more depressive symptoms.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
State Anxiety for Younger Adults
Emotional well-being measured by the State Anxiety Inventory (SAI) for younger adults. The SAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater state anxiety.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
State Anxiety for Older Adults
Emotional well-being measured by the State Anxiety Inventory (SAI) for older adults. The SAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater state anxiety.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Trait Anxiety for Younger Adults
Emotional well-being measured by the Trait Anxiety Inventory (TAI) for younger adults. The TAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater trait anxiety.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Trait Anxiety for Older Adults
Emotional well-being measured by the Trait Anxiety Inventory (TAI) for older adults. The TAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater trait anxiety.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Recovery (Systolic Blood Pressure) for Younger Adults
Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Recovery (Systolic Blood Pressure) for Older Adults
Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Recovery (Heart Rate) for Younger Adults
Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Recovery (Heart Rate) for Older Adults
Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Recovery (Breathing Rate) for Younger Adults
Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in breathing rate from cognitive tasks to recovery rest
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Recovery (Breathing Rate) for Older Adults
Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in breathing rate from cognitive tasks to recovery rest
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Reactivity (Systolic Blood Pressure) for Younger Adults
Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from rest to cognitive tasks
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Reactivity (Systolic Blood Pressure) for Older Adults
Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from rest to cognitive tasks
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Reactivity (Heart Rate) for Younger Adults
Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in heart rate from rest to cognitive tasks
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Reactivity (Heart Rate) for Older Adults
Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Reactivity (Breathing Rate) for Younger Adults
Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in breathing rate from rest to cognitive tasks
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Stress Reactivity (Breathing Rate) for Older Adults
Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in breathing rate from rest to cognitive tasks
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Arterial Spin Labeling (ASL) for Younger Adults
Cerebral blood flow was measured at pre-training resting state and post-training paced-breathing.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Arterial Spin Labeling (ASL) for Older Adults
Cerebral blood flow was measured at pre-training resting state and post-training paced-breathing.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
High Frequency (HF) HRV for Younger Adults
HRV measured by high frequency (HF) HRV for younger adults. HF-HRV was quantified as the spectral power of interbeat interval variability within the high frequency range (typically 0.15-0.40 Hz), which reflects parasympathetic (vagal) activity. In this study, HF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the high frequency band. Measurements are expressed in units of milliseconds squared (ms²). Higher HF-HRV values indicate increased parasympathetic modulation and are generally associated with improved autonomic regulation and better cognitive performance.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
High Frequency (HF) HRV for Older Adults
HRV measured by high frequency (HF) HRV for older adults. HF-HRV was quantified as the spectral power of interbeat interval variability within the high frequency range (typically 0.15-0.40 Hz), which reflects parasympathetic (vagal) activity. In this study, HF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the high frequency band. Measurements are expressed in units of milliseconds squared (ms²). Higher HF-HRV values indicate increased parasympathetic modulation and are generally associated with improved autonomic regulation and better cognitive performance.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Low Frequency (LF) HRV for Younger Adults
HRV measured by low frequency (LF) HRV for younger adults. LF-HRV was quantified as the spectral power of interbeat interval variability within the low frequency range (typically 0.04-0.15 Hz), which reflects the combined influences of sympathetic and parasympathetic activity. In this study, LF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the low frequency band. Measurements are expressed in units of milliseconds squared (ms²). Although LF-HRV reflects contributions from both branches of the autonomic nervous system, higher LF-HRV values can indicate enhanced autonomic modulation, with interpretation made in the context of overall autonomic balance.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Low Frequency (LF) HRV for Older Adults
HRV measured by low frequency (LF) HRV for older adults. LF-HRV was quantified as the spectral power of interbeat interval variability within the low frequency range (typically 0.04-0.15 Hz), which reflects the combined influences of sympathetic and parasympathetic activity. In this study, LF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the low frequency band. Measurements are expressed in units of milliseconds squared (ms²). Although LF-HRV reflects contributions from both branches of the autonomic nervous system, higher LF-HRV values can indicate enhanced autonomic modulation, with interpretation made in the context of overall autonomic balance.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
The Root Mean Squared Successive Differences (RMSSD) HRV for Younger Adults
HRV measured by the root mean square of successive differences (RMSSD) for younger adults. RMSSD (Root Mean Square of Successive Differences) is a time-domain measure that quantifies the variability between successive interbeat intervals, primarily reflecting parasympathetic (vagal) activity. In this study, RMSSD was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals, and RMSSD was computed as the square root of the mean of the squared differences between consecutive interbeat intervals. Measurements are expressed in milliseconds (ms). Higher RMSSD values indicate increased parasympathetic modulation, generally associated with improved autonomic regulation and better cardiovascular and cognitive performance.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
The Root Mean Squared Successive Differences (RMSSD) HRV for Older Adults
HRV measured by the root mean square of successive differences (RMSSD) for older adults. RMSSD (Root Mean Square of Successive Differences) is a time-domain measure that quantifies the variability between successive interbeat intervals, primarily reflecting parasympathetic (vagal) activity. In this study, RMSSD was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals, and RMSSD was computed as the square root of the mean of the squared differences between consecutive interbeat intervals. Measurements are expressed in milliseconds (ms). Higher RMSSD values indicate increased parasympathetic modulation, generally associated with improved autonomic regulation and better cardiovascular and cognitive performance.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by C-reactive Protein for Younger Adults
Inflammation measured by salivary C-reactive protein (CRP) for younger adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by C-reactive Protein for Older Adults
Inflammation measured by salivary C-reactive protein (CRP) for older adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by IL-1b Levels for Younger Adults
Inflammation measured by salivary IL-1b levels for younger adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by IL-1b Levels for Older Adults
Inflammation measured by salivary IL-1b levels for older adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by IL-6 Levels for Younger Adults
Inflammation measured by salivary IL-6 levels for younger adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by IL-6 Levels for Older Adults
Inflammation measured by salivary IL-6 levels for older adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by IL-8 Levels for Younger Adults
Inflammation measured by salivary IL-8 levels for younger adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by IL-8 Levels for Older Adults
Inflammation measured by salivary IL-8 levels for older adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by TNF-a Levels for Younger Adults
Inflammation measured by salivary TNF-a levels for younger adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Inflammation Measured by TNF-a Levels for Older Adults
Inflammation measured by salivary TNF-a levels for older adults
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Amyloid Beta 40 (Aβ40) for Younger Adults
Plasma Aβ40 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for younger adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Amyloid Beta 40 (Aβ40) for Older Adults
Plasma Aβ40 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Amyloid Beta 42 (Aβ42) Younger Adults
Plasma Aβ42 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for younger adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Amyloid Beta 42 (Aβ42) for Older Adults
Plasma Aβ42 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Phosphorylated Tau 181 (pTau) for Younger Adults
Plasma pTau levels at pre- and post-intervention were reported for HRV-increase and HRV-decrease group for younger adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Phosphorylated Tau 181 (pTau) for Older Adults
Plasma pTau levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Total Tau (tTau) for Younger Adults
Plasma tTau levels at pre- and post-intervention were reported for HRV-increase and HRV-decrease group for younger adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Plasma Total Tau (tTau) for Older Adults
Plasma tTau levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
LC-innervated Subregion Volume in the Hippocampus for Younger Adults
LC-innervated subregion volume in the hippocampus at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
LC-innervated Subregion Volume in the Hippocampus for Older Adults
LC-innervated subregion volume in the hippocampus at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Cortical Volume in the Left Orbitofrontal Cortex for Younger Adults
Left orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Cortical Volume in the Left Orbitofrontal Cortex for Older Adults
Left orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Cortical Volume in the Right Orbitofrontal Cortex for Younger Adults
Right orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
Cortical Volume in the Right Orbitofrontal Cortex for Older Adults
Right orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
mPFC-left Amygdala Resting-state Functional Connectivity for Younger Adults (Post-Pre)
The strength of resting-state functional connectivity between mPFC and the left amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
mPFC-left Amygdala Resting-state Functional Connectivity for Older Adults (Post-Pre)
The strength of resting-state functional connectivity between mPFC and the left amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
mPFC-left Amygdala Resting-state Functional Connectivity for Younger Adults (ANOVA)
The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the left amygdala. Higher values indicate greater connectivity.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
mPFC-left Amygdala Resting-state Functional Connectivity for Older Adults (ANOVA)
The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the left amygdala. Higher values indicate greater connectivity.
Time frame: Time 1 (Baseline), Time 2 (5 weeks)
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