Monoterpene Exposure During a Forest Bathing Intervention
Conditions
Brief summary
This pilot study evaluates the role terpenes play in the stress-reducing effects of a forest bathing intervention. Participants will participate in two interventions in random order: 1) terpene exposure and 2) no terpene exposure.
Detailed description
The investigators will use an individual-level crossover design in which each session is conducted independently and on different days. Participants will be outfitted with a powered air purifying respirator (PAPR) to selectively modulate exposure to a natural suite of forest-derived volatile organic compounds (VOCs) while present in forest environments. Each participant will undergo two forest bathing sessions, one in which VOCs are not filtered (treatment condition), and one in which they are filtered (control condition). Sessions will be separated by a washout period of at least 8 days for each participant, and order will be counterbalanced. The investigators will estimate the average effect of treatment over 40 distinct treatment days against 40 distinct control/filtered days. The power and sample size calculations (N = 40) were determined using previous nature exposure studies of similar cross-over design. The study is adequately powered assuming the conventional targets of α = 0.05 and β = 0.80 with a 10% anticipated dropout rate, and including temperature, wind, and light variability during treatment days. The specific aim of this project is to 1) assess whether VOC inhalation regulates increases in the high frequency (HF) (ms2) component of heart rate variability (HRV) as the primary outcome (with decreases in blood pressure, heart rate, self-reported stress, and levels of inflammatory cytokines in serum included as secondary outcomes); and 1a) assess the degree of association of absorbed dose of six forest-derived VOCs (i.e., α-pinene, β-pinene, β-myrcene, Δ-3-carene, limonene, β- carophyllene) in serum with these outcomes.
Interventions
BEHAVIORALForest bathing
Participants will be seated in a forest environment for an hour-long exposure to the forest
Sponsors
National Center for Complementary and Integrative Health (NCCIH)
University of Washington
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Investigator)
Masking description
Participants and research staff conducting the intervention will be masked to the exposure
Intervention model description
Participants are assigned to both arms in random order
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* 18 years and older * Non-smoker * Physically capable of walking for approximately 15-20 min from the study vehicle to the clinic and experimental locations.
Exclusion criteria
* Pregnancy * Current or prior diagnosis of neurologic, hypertensive, psychiatric, respiratory disorder, or anosmia/hyposmia * Some types of medication. * Olfactory sensitivity threshold (assessed via UPSIT® test kit (Sensonics International, Haddon Heights, NJ) At enrollment, participants will complete a baseline survey on demographics, personality traits, and regular nature contact and perceptions. Study staff will also use the clinically-validated UPSIT® test kit (Sensonics International, Haddon Heights, NJ) to evaluate olfactory sensitivity and identify/exclude participants with undiagnosed smell loss. Study staff will work with participants to schedule their forest bathing sessions and review instructions on how to prepare (e.g., by avoiding alcohol, marijuana, and certain foods, drinks, and household cleaning products with high terpene concentrations 24 hrs before their session).
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Baseline HF (ms^2) Component of HRV | At baseline (pre-exposure) | Assess whether VOC inhalation regulates psychophysiological outcomes of the terpenes-on vs. terpenes-off sessions. Ln High Frequency Heart Rate Variability at baseline. |
| Changes in the HF (ms^2) Component of HRV | At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assess whether VOC inhalation regulates psychophysiological outcomes of the terpenes-on vs. terpenes-off sessions. Ln High Frequency Heart Rate Variability at T2 (20 minutes into duration of exposure for each session) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Beats Per Minute (BPM) | At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using mobile physiology equipment BPM at time point 4 (60 minutes of exposure) |
| Skin Conductance (μS) | At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using mobile physiology equipment Skin conductance levels at time point 2 (20 minutes into exposure) |
| Self-reported Positive Affect | At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Positive affect at time point 2 (20 minutes of exposure) Higher scale scores are indicative of better outcome Range 5-50 |
| Self-reported Stress | At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using a single-item self report non-validated scale Self-reported stress at time point 2 (20 minutes of exposure) Higher scale score indicative of worse outcome Range 1-5 |
| Self-reported Negative Affect | At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Negative affect at time point 2 (20 minutes of exposure) Higher score on scale indicative of worse outcome Range 5-50 |
| Levels of Cortisol in Serum (ng/mL) | At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using blood serum collected via standard clinical methods Cortisol levels at time point 4 (60 minutes of exposure). |
| Blood Pressure (Systolic in mmHg) | At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using mobile physiology equipment Systolic blood pressure at T4 (60 minutes of exposure) |
| Level of TNF-alpha | At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using blood serum collected via standard clinical methods TNF-alpha levels at time point 4 (60 minutes of exposure). |
| Levels of Il-6 | At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using blood serum collected via standard clinical methods IL-6 levels at time point 4 (60 minutes of exposure). |
| Baseline Blood Pressure (Diastolic in mmHg) | At baseline (pre-exposure). | Assessed using mobile physiology equipment Diastolic blood pressure at baseline. |
| Levels of CRP | At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using blood serum collected via standard clinical methods. CRP levels at time point 4 (60 minutes of exposure). |
| Blood Pressure (Diastolic in mmHg) | At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)). | Assessed using mobile physiology equipment Diastolic blood pressure at T4 (60 minutes of exposure) |
Other
| Measure | Time frame | Description |
|---|---|---|
| Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | Time point 4 (60 min) for absorbed dose associations with same time point for DBP, SBP, Cortisol, Il-6, TNF-alpha, and CRP; and associations with Time point 2 (20 minutes) for HRV, SCL, positive affect, negative affect, self-reported stress, heart rate. | Assess the association of absorbed dose (µg/mL) of forest-derived VOCs in serum with primary and secondary outcomes. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Terpenes On, Then Terpenes Off Participants first received a forest bathing session with no filtration of terpenes from inhaled air (terpenes on) in a forest environment during an hour-long exposure to the forest. After a washout period of at least eight days, they then received a forest bathing session with filtration of terpenes from inhaled air (terpenes off) in a forest environment during an hour-long exposure to the forest. | 21 |
| Terpenes Off, Then Terpenes On Participants first received a forest bathing session with no filtration of terpenes from inhaled air (terpenes on) in a forest environment during an hour-long exposure to the forest. After a washout period of at least eight days, they then received a forest bathing session with filtration of terpenes from inhaled air (terpenes off) during a forest environment for an hour-long exposure to the forest. | 22 |
| Total | 43 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| First Session | Withdrawal by Subject | 0 | 1 |
| Washout Period | Excluded before second session | 1 | 1 |
| Washout Period | Lost to Follow-up | 1 | 2 |
| Washout Period | Physician Decision | 1 | 1 |
| Washout Period | Withdrawal by Subject | 0 | 4 |
Baseline characteristics
| Characteristic | Terpenes On, Then Terpenes Off | Total | Terpenes Off, Then Terpenes On |
|---|---|---|---|
| Age, Continuous | 33.0 years STANDARD_DEVIATION 14.2 | 35.1 years STANDARD_DEVIATION 14.3 | 37.1 years STANDARD_DEVIATION 14.5 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 2 Participants | 5 Participants | 3 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 19 Participants | 38 Participants | 19 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 1 Participants | 1 Participants |
| Race (NIH/OMB) Asian | 2 Participants | 5 Participants | 3 Participants |
| Race (NIH/OMB) Black or African American | 1 Participants | 3 Participants | 2 Participants |
| Race (NIH/OMB) More than one race | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 2 Participants | 3 Participants | 1 Participants |
| Race (NIH/OMB) White | 16 Participants | 31 Participants | 15 Participants |
| Region of Enrollment United States | 21 participants | 43 participants | 22 participants |
| Sex/Gender, Customized Female | 12 Participants | 22 Participants | 10 Participants |
| Sex/Gender, Customized Male | 7 Participants | 17 Participants | 10 Participants |
| Sex/Gender, Customized Prefer to self-describe/non-binary | 2 Participants | 4 Participants | 2 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 0 / 43 | 0 / 43 |
| other Total, other adverse events | 0 / 43 | 0 / 43 |
| serious Total, serious adverse events | 0 / 43 | 0 / 43 |
Outcome results
Primary
Baseline HF (ms^2) Component of HRV
Assess whether VOC inhalation regulates psychophysiological outcomes of the terpenes-on vs. terpenes-off sessions. Ln High Frequency Heart Rate Variability at baseline.
Time frame: At baseline (pre-exposure)
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Baseline HF (ms^2) Component of HRV | 6.48 ms^2 | Standard Deviation 1.4 |
| Terpenes Off | Baseline HF (ms^2) Component of HRV | 6.34 ms^2 | Standard Deviation 1.55 |
Primary
Changes in the HF (ms^2) Component of HRV
Assess whether VOC inhalation regulates psychophysiological outcomes of the terpenes-on vs. terpenes-off sessions. Ln High Frequency Heart Rate Variability at T2 (20 minutes into duration of exposure for each session)
Time frame: At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Changes in the HF (ms^2) Component of HRV | 6.65 ms^2 | Standard Deviation 1.33 |
| Terpenes Off | Changes in the HF (ms^2) Component of HRV | 6.48 ms^2 | Standard Deviation 1.14 |
p-value: 0.914Mixed Models Analysis
Secondary
Baseline Blood Pressure (Diastolic in mmHg)
Assessed using mobile physiology equipment Diastolic blood pressure at baseline.
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Baseline Blood Pressure (Diastolic in mmHg) | 67.8 mmHg | Standard Deviation 10.8 |
| Terpenes Off | Baseline Blood Pressure (Diastolic in mmHg) | 66.1 mmHg | Standard Deviation 11 |
Secondary
Beats Per Minute (BPM)
Assessed using mobile physiology equipment BPM at time point 4 (60 minutes of exposure)
Time frame: At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Beats Per Minute (BPM) | 61.4 BPM | Standard Deviation 11.9 |
| Terpenes Off | Beats Per Minute (BPM) | 63.0 BPM | Standard Deviation 13.7 |
p-value: 0.905Mixed Models Analysis
Secondary
Beats Per Minute (BPM)
Assessed using mobile physiology equipment BPM at baseline.
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Beats Per Minute (BPM) | 66.3 BPM | Standard Deviation 13 |
| Terpenes Off | Beats Per Minute (BPM) | 66.6 BPM | Standard Deviation 13.3 |
Secondary
Blood Pressure (Diastolic in mmHg)
Assessed using mobile physiology equipment Diastolic blood pressure at T4 (60 minutes of exposure)
Time frame: At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Blood Pressure (Diastolic in mmHg) | 75.4 mmHg | Standard Deviation 9.86 |
| Terpenes Off | Blood Pressure (Diastolic in mmHg) | 73.2 mmHg | Standard Deviation 11.1 |
p-value: 0.554Mixed Models Analysis
Secondary
Blood Pressure (Systolic in mmHg)
Assessed using mobile physiology equipment Systolic blood pressure at baseline
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Blood Pressure (Systolic in mmHg) | 119 mmHg | Standard Deviation 12.4 |
| Terpenes Off | Blood Pressure (Systolic in mmHg) | 117 mmHg | Standard Deviation 13.9 |
Secondary
Blood Pressure (Systolic in mmHg)
Assessed using mobile physiology equipment Systolic blood pressure at T4 (60 minutes of exposure)
Time frame: At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Blood Pressure (Systolic in mmHg) | 123 mmHg | Standard Deviation 16.9 |
| Terpenes Off | Blood Pressure (Systolic in mmHg) | 121 mmHg | Standard Deviation 14 |
p-value: 0.852Mixed Models Analysis
Secondary
Level of TNF-alpha
Assessed using blood serum collected via standard clinical methods TNF-alpha levels at baseline
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Level of TNF-alpha | 4.03 pg/mL | Standard Deviation 2.75 |
| Terpenes Off | Level of TNF-alpha | 3.72 pg/mL | Standard Deviation 2.64 |
Secondary
Level of TNF-alpha
Assessed using blood serum collected via standard clinical methods TNF-alpha levels at time point 4 (60 minutes of exposure).
Time frame: At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Level of TNF-alpha | 3.80 pg/mL | Standard Deviation 2.71 |
| Terpenes Off | Level of TNF-alpha | 4.27 pg/mL | Standard Deviation 2.84 |
p-value: 0.166Mixed Models Analysis
Secondary
Levels of Cortisol in Serum (ng/mL)
Assessed using blood serum collected via standard clinical methods Cortisol levels at time point 4 (60 minutes of exposure).
Time frame: At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Levels of Cortisol in Serum (ng/mL) | 98.6 ng/mL | Standard Deviation 43.6 |
| Terpenes Off | Levels of Cortisol in Serum (ng/mL) | 109.0 ng/mL | Standard Deviation 60 |
p-value: 0.716Mixed Models Analysis
Secondary
Levels of Cortisol in Serum (ng/mL)
Assessed using blood serum collected via standard clinical methods Cortisol levels at baseline
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Levels of Cortisol in Serum (ng/mL) | 117 ng/mL | Standard Deviation 57.8 |
| Terpenes Off | Levels of Cortisol in Serum (ng/mL) | 124 ng/mL | Standard Deviation 55.1 |
Secondary
Levels of CRP
Assessed using blood serum collected via standard clinical methods. CRP levels at baseline
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Levels of CRP | 9.93 mg/L | Standard Deviation 6.43 |
| Terpenes Off | Levels of CRP | 13.6 mg/L | Standard Deviation 13.7 |
Secondary
Levels of CRP
Assessed using blood serum collected via standard clinical methods. CRP levels at time point 4 (60 minutes of exposure).
Time frame: At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Levels of CRP | 9.99 mg/L | Standard Deviation 7.83 |
| Terpenes Off | Levels of CRP | 13.4 mg/L | Standard Deviation 12.5 |
p-value: 0.724Mixed Models Analysis
Secondary
Levels of Il-6
Assessed using blood serum collected via standard clinical methods IL-6 levels at baseline
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Levels of Il-6 | 0.585 pg/mL | Standard Deviation 0.569 |
| Terpenes Off | Levels of Il-6 | 0.591 pg/mL | Standard Deviation 0.776 |
Secondary
Levels of Il-6
Assessed using blood serum collected via standard clinical methods IL-6 levels at time point 4 (60 minutes of exposure).
Time frame: At time point 4 (60 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Levels of Il-6 | 0.547 pg/mL | Standard Deviation 0.609 |
| Terpenes Off | Levels of Il-6 | 0.763 pg/mL | Standard Deviation 0.82 |
p-value: 0.046Mixed Models Analysis
Secondary
Self-reported Negative Affect
Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Negative affect at baseline Higher score on scale indicative of worse outcome Range 5-50
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Self-reported Negative Affect | 5.81 Score on a scale | Standard Deviation 1.11 |
| Terpenes Off | Self-reported Negative Affect | 5.92 Score on a scale | Standard Deviation 1.46 |
Secondary
Self-reported Negative Affect
Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Negative affect at time point 2 (20 minutes of exposure) Higher score on scale indicative of worse outcome Range 5-50
Time frame: At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Self-reported Negative Affect | 5.13 Score on a scale | Standard Deviation 0.421 |
| Terpenes Off | Self-reported Negative Affect | 5.31 Score on a scale | Standard Deviation 0.749 |
p-value: 0.265Mixed Models Analysis
p-value: 0.63ANOVA
Secondary
Self-reported Positive Affect
Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Positive affect at baseline Higher scale scores are indicative of better outcome Range 5-50
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Self-reported Positive Affect | 12.0 Score on a scale | Standard Deviation 3.74 |
| Terpenes Off | Self-reported Positive Affect | 12.2 Score on a scale | Standard Deviation 4.59 |
Secondary
Self-reported Positive Affect
Assessed using the shortened Positive and Negative Affect Schedule (PANAS) Positive affect at time point 2 (20 minutes of exposure) Higher scale scores are indicative of better outcome Range 5-50
Time frame: At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Self-reported Positive Affect | 12.1 Score on a scale | Standard Deviation 4 |
| Terpenes Off | Self-reported Positive Affect | 11.3 Score on a scale | Standard Deviation 4.38 |
p-value: 0.21Mixed Models Analysis
Comparison: Exploratory ANOVA results comparing full and reduced models to test the effect of terpene exposure on pattern of outcome over time.p-value: 0.57ANOVA
Secondary
Self-reported Stress
Assessed using a single-item self report non-validated scale Self-reported stress at time point 2 (20 minutes of exposure) Higher scale score indicative of worse outcome Range 1-5
Time frame: At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Self-reported Stress | 1.09 Score on a scale | Standard Deviation 0.39 |
| Terpenes Off | Self-reported Stress | 1.17 Score on a scale | Standard Deviation 0.447 |
p-value: 0.921Mixed Models Analysis
p-value: 0.82ANOVA
Secondary
Self-reported Stress
Assessed using a single-item self report non-validated scale Self-reported stress at baseline Higher scale score indicative of worse outcome Range 1-5
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Self-reported Stress | 1.44 Score on a scale | Standard Deviation 0.698 |
| Terpenes Off | Self-reported Stress | 1.57 Score on a scale | Standard Deviation 0.817 |
Secondary
Skin Conductance (μS)
Assessed using mobile physiology equipment Skin conductance levels at baseline.
Time frame: At baseline (pre-exposure).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Skin Conductance (μS) | 3.58 microsiemens (µS) | Standard Deviation 3.94 |
| Terpenes Off | Skin Conductance (μS) | 3.84 microsiemens (µS) | Standard Deviation 5.14 |
Secondary
Skin Conductance (μS)
Assessed using mobile physiology equipment Skin conductance levels at time point 2 (20 minutes into exposure)
Time frame: At time point 2 (20 minutes into duration of exposure for Session 1 and Session 2 (which occurred at least 8 days after Session 1)).
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Terpenes On | Skin Conductance (μS) | 3.28 microsiemens (µS) | Standard Deviation 3.76 |
| Terpenes Off | Skin Conductance (μS) | 4.14 microsiemens (µS) | Standard Deviation 5.94 |
p-value: 0.076Mixed Models Analysis
Comparison: Exploratory ANOVA results comparing full and reduced models to test the effect of terpene exposure on pattern of outcome over time.p-value: 0.02ANOVA
Other Pre-specified
Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL)
Assess the association of absorbed dose (µg/mL) of forest-derived VOCs in serum with primary and secondary outcomes.
Time frame: Time point 4 (60 min) for absorbed dose associations with same time point for DBP, SBP, Cortisol, Il-6, TNF-alpha, and CRP; and associations with Time point 2 (20 minutes) for HRV, SCL, positive affect, negative affect, self-reported stress, heart rate.
Population: Participants who participated in at least one session were included in analyses though some participant data were missing due to temporary equipment failure (e.g., mobile physiology) or sample collection obstacles (e.g., serum).
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | Ln-HR HRV | 1.06 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | SCL | -7.31 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | DBP | 11.89 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | SBP | 17.55 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | HR | 7.16 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | PA | 3.75 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | NA | 0.15 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | Self-reported stress | -0.38 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | Cortisol | -45.45 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | Il-6 | -0.60 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | TNF-alpha | -5.73 correlation coefficient |
| Terpenes On | Degree of Association of Sum Composite of Absorbed Dose of VOCs in Serum (μg/mL) | CRP | -0.70 correlation coefficient |