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 %.

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 %.

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 %.

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 %.

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).

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.

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.

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.

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.

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.

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.

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.

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.

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.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in breathing rate from cognitive tasks to recovery rest

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in breathing rate from cognitive tasks to recovery rest

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from rest to cognitive tasks

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from rest to cognitive tasks

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in heart rate from rest to cognitive tasks

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in breathing rate from rest to cognitive tasks

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in breathing rate from rest to cognitive tasks

Cerebral blood flow was measured at pre-training resting state and post-training paced-breathing.

Cerebral blood flow was measured at pre-training resting state and post-training paced-breathing.

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.

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.

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.

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.

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.

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.

Inflammation measured by salivary C-reactive protein (CRP) for younger adults

Inflammation measured by salivary C-reactive protein (CRP) for older adults

Inflammation measured by salivary IL-1b levels for younger adults

Inflammation measured by salivary IL-1b levels for older adults

Inflammation measured by salivary IL-6 levels for younger adults

Inflammation measured by salivary IL-6 levels for older adults

Inflammation measured by salivary IL-8 levels for younger adults

Inflammation measured by salivary IL-8 levels for older adults

Inflammation measured by salivary TNF-a levels for younger adults

Inflammation measured by salivary TNF-a levels for older adults

Plasma Aβ40 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for younger adults.

Plasma Aβ40 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.

Plasma Aβ42 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for younger adults.

Plasma Aβ42 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.

Plasma pTau levels at pre- and post-intervention were reported for HRV-increase and HRV-decrease group for younger adults.

Plasma pTau levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.

Plasma tTau levels at pre- and post-intervention were reported for HRV-increase and HRV-decrease group for younger adults.

Plasma tTau levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group 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 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 older adults.

Left orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.

Left orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.

Right orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.

Right orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.

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).

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).

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.

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.

Processing speed performance measured by NIH Toolbox Pattern Comparison Processing Speed Test (PCPS).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating faster processing speed.

Processing speed performance measured by NIH Toolbox Pattern Comparison Processing Speed Test (PCPS).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating faster processing speed.

Inhibitory control performance measured by NIH Toolbox Flanker Inhibitory Control and Attention Test (Flanker).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating better Inhibitory Control and Attention.

Inhibitory control performance measured by NIH Toolbox Flanker Inhibitory Control and Attention Test (Flanker).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating better Inhibitory Control and Attention.

Sustained attention performance was measured by Sustained Attention to Response Test (SART).

A commission error was calculated as the number of button press for 25 no-go trials, and an omission error was calculated as the number of no button press for 200 go trials in younger adults. The number of errors range from 0 to 25 for commission errors and from 0 to 200 for omission errors. A higher number of omission and commission errors indicates worse sustained attention performance.

Sustained attention performance was measured by Sustained Attention to Response Test (SART).

A commission error was calculated as the number of button press for 25 no-go trials, and an omission error was calculated as the number of no button press for 200 go trials in older adults. The number of errors range from 0 to 25 for commission errors and from 0 to 200 for omission errors. A higher number of omission and commission errors indicates worse sustained attention performance.

Recognition memory performance based on average proportion of previously presented images that were correctly identified (i.e., hits) by younger adults

Recognition memory performance based on average proportion of previously presented images that were correctly identified (i.e., hits) by older adults

Recognition memory performance based on average proportion of images not previously presented that were incorrectly identified as seen (i.e., False Alarms) by younger adults

Recognition memory performance based on average proportion of images not previously presented that were incorrectly identified as seen (i.e., False Alarms) by older adults

Average proportion of previously presented images that were correctly recalled by younger adults

Average proportion of previously presented images that were correctly recalled by older adults

Stress measured by salivary cortisol levels for younger adults

Participants in this group were between the ages of 55 and 80.

Half of the older participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.

Participants in this group were between the ages of 55 and 80.

Half of the older participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.

Total of all reporting groups

Participants in this group were between the ages of 18 and 35.

Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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).

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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).

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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 %.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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 %.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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 %.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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 %.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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).

Population analyzed was composed by all randomization subjects who completed the decision making task, who were unfamiliar with the task and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed the decision making task, whose data quality was sufficient for data analysis and who were unfamiliar with the task.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

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.

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in breathing rate from cognitive tasks to recovery rest

Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.