Aging
Conditions
Keywords
oxytocin, socioemotional functioning, trust, amygdala, aging
Brief summary
This study will investigate the extent to which intranasal oxytocin affects changes in social decision making and evaluations of others. Oxytocin is a hormone that naturally occurs in the body and the brain and has been shown to be relevant for many behaviors, particularly in social situations. Research on the effects of oxytocin in aging is very scarce; therefore, the purpose of this research project is to determine the effects of oxytocin on socioemotional aging.
Detailed description
In order to demonstrate oxytocin as a causal mechanism in socioemotional aging, the investigators propose to temporarily elevate oxytocin levels and then measure activity in the brain while participants engage in socially relevant tasks. Participants in this study will be randomly assigned (much like flipping a coin) to receive either a single administration of oxytocin or a placebo (a substance that looks like the oxytocin but does not have any active drug). Neither participants nor the investigator will know to which condition each participant is assigned. Prior to being enrolled into the study a screening to determine eligibility will be conducted. Once the screening visit is completed and it has been determined that subjects can be randomized into the study, an appointment will be scheduled for the full study visit. The purpose of the screening is to determine whether the individual is eligible for participation in the study and will consist of a series of questions about demographics and health history, two saliva samples, two short tasks, blood test, and brief meeting with a licensed clinician to ensure that it is safe for the individual to take part in the magnetic resonance imaging (MRI) and drug administration. The study visit will comprise two collections of saliva for laboratory tests prior to and following the oxytocin administration in order to measure levels of the hormone in the body at baseline and after the spray. Saliva samples will also allow for an examination of how oxytocin-related genes may impact cognition and behavior during study tasks. Participants will work on various social tasks while in the MRI scanner, and response accuracy, response time, and brain activity will be recorded. After the scan, participants will complete a series of brief questionnaires on paper and on the computer.
Interventions
DRUGOxytocin spray
single dose of 24 IU oxytocin, self-administered intranasally (IN)
DRUGPlacebo spray
single dose of 24 IU placebo (same solution as oxytocin spray but without oxytocin), self-administered intranasally (IN)
Sponsors
University of Florida
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
ALL
Age
18 Years to 85 Years
Healthy volunteers
Yes
Inclusion criteria
* Between the ages of 18-30 years or 63-85 years * English fluency * Caucasian * Right-handed
Exclusion criteria
* Pregnant or possibly pregnant * Breastfeeding * Claustrophobia * Currently on vasoconstrictors, pseudoephedrine or antidiuretic medication * Large pieces of metal in the body, particularly in the face or neck * Piercings or metal implants that cannot be removed from the body * Surgery on the brain or any prior serious brain damage or disease * Dementia or severe cognitive disorders * History of hyponatremia, Syndrome of Inappropriate Antidiuretic Hormone, psychogenic polydipsia, or motion disorder
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Extent of Trust Behavior | 45 minutes after drug/placebo administration | Average amount of monetary units invested in the context of the Trust/Lottery Game. The theoretical range was 0 to 72 monetary units across all 24 trials. Participants invested in 12 social (human person) and 12 non-social (computer) trials.The mean average amount of monetary units invested was calculated for social and non-social trials separately. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Meta-Mood | 2.5 hours after drug/placebo administration | Mean self-reported level of meta-mood for the two subscales attention to feelings and clarity of feelings. Response scale ranged from 1 to 5, with higher scores indicating more attention to feelings and greater clarity of feelings, respectively. The mean score for the subscales were calculated. |
| Functional Connectivity (Resting fMRI) | 1.5 hours after oxytocin/placebo administration | The functional connectivity (strength measure in units on a scale) between amygdala and medial prefrontal cortex was measured via a resting functional magnetic resonance imaging scan (participants looked at a fixation cross while images of their brain at rest were taken). Functional connectivity is the connectivity between brain regions (i.e., amygdala and medial prefrontal cortex) that share functional properties. It is defined as the temporal correlation between spatially remote neurophysiological events, expressed as deviation from statistical independence across these events in distributed neuronal groups and areas. A mean of this correlation (connectivity strength) was computed and transformed into z-scores (r to z transformation). The z-scores ranged from -2 to +2 with higher scores representing a greater resting-state functional connectivity. |
Countries
United States
Participant flow
Recruitment details
Participants were recruited between 08/2013 and 09/2014. Recruitment phone calls were conducted at the Social-Cognitive and Affective Development Lab at University of Florida.
Participants by arm
| Arm | Count |
|---|---|
| Oxytocin Spray single dose of 24 IU oxytocin, self-administered intranasally (IN) | 55 |
| Placebo Spray single dose of 24 IU saline, self-administered intranasally (IN) | 51 |
| Total | 106 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Lost to Follow-up | 2 | 1 |
| Overall Study | Withdrawal by Subject | 0 | 1 |
Baseline characteristics
| Characteristic | Oxytocin Spray | Placebo Spray | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 21 Participants | 25 Participants | 46 Participants |
| Age, Categorical Between 18 and 65 years | 34 Participants | 26 Participants | 60 Participants |
| Region of Enrollment United States | 55 participants | 51 participants | 106 participants |
| Sex: Female, Male Female | 28 Participants | 27 Participants | 55 Participants |
| Sex: Female, Male Male | 27 Participants | 24 Participants | 51 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 55 | 0 / 51 |
| serious Total, serious adverse events | 0 / 55 | 0 / 51 |
Outcome results
Primary
Extent of Trust Behavior
Average amount of monetary units invested in the context of the Trust/Lottery Game. The theoretical range was 0 to 72 monetary units across all 24 trials. Participants invested in 12 social (human person) and 12 non-social (computer) trials.The mean average amount of monetary units invested was calculated for social and non-social trials separately.
Time frame: 45 minutes after drug/placebo administration
Population: All study participants who had undergone the screening as well as the full visit (n = 102).
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Oxytocin Spray | Extent of Trust Behavior | non-social trials | 39.03 monetary units | Standard Error 2.55 |
| Oxytocin Spray | Extent of Trust Behavior | social trials | 45.11 monetary units | Standard Error 1.86 |
| Placebo Spray | Extent of Trust Behavior | non-social trials | 44.42 monetary units | Standard Error 2.54 |
| Placebo Spray | Extent of Trust Behavior | social trials | 46.06 monetary units | Standard Error 2.47 |
Secondary
Functional Connectivity (Resting fMRI)
The functional connectivity (strength measure in units on a scale) between amygdala and medial prefrontal cortex was measured via a resting functional magnetic resonance imaging scan (participants looked at a fixation cross while images of their brain at rest were taken). Functional connectivity is the connectivity between brain regions (i.e., amygdala and medial prefrontal cortex) that share functional properties. It is defined as the temporal correlation between spatially remote neurophysiological events, expressed as deviation from statistical independence across these events in distributed neuronal groups and areas. A mean of this correlation (connectivity strength) was computed and transformed into z-scores (r to z transformation). The z-scores ranged from -2 to +2 with higher scores representing a greater resting-state functional connectivity.
Time frame: 1.5 hours after oxytocin/placebo administration
Population: All study participants who had undergone the screening as well as the full visit and had reliable resting fMRI scan data (e.g., low extent of head motion) (n = 79).
| Arm | Measure | Value (LEAST_SQUARES_MEAN) |
|---|---|---|
| Oxytocin Spray | Functional Connectivity (Resting fMRI) | 0.58 z-scores |
| Placebo Spray | Functional Connectivity (Resting fMRI) | 0.48 z-scores |
Secondary
Meta-Mood
Mean self-reported level of meta-mood for the two subscales attention to feelings and clarity of feelings. Response scale ranged from 1 to 5, with higher scores indicating more attention to feelings and greater clarity of feelings, respectively. The mean score for the subscales were calculated.
Time frame: 2.5 hours after drug/placebo administration
Population: All study participants who had undergone the screening as well as the full visit (n = 102).
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Oxytocin Spray | Meta-Mood | n = 24 older men (63 to 85 years) | 3.38 units on a scale | Standard Error 0.18 |
| Oxytocin Spray | Meta-Mood | n = 30 older women (63 to 85 years) | 3.23 units on a scale | Standard Error 0.18 |
| Oxytocin Spray | Meta-Mood | n = 25 young men (18 to 30 years) | 3.54 units on a scale | Standard Error 0.17 |
| Oxytocin Spray | Meta-Mood | n = 23 young women (18 to 30 years) | 4.04 units on a scale | Standard Error 0.19 |
| Placebo Spray | Meta-Mood | n = 23 young women (18 to 30 years) | 3.68 units on a scale | Standard Error 0.21 |
| Placebo Spray | Meta-Mood | n = 24 older men (63 to 85 years) | 2.977 units on a scale | Standard Error 0.19 |
| Placebo Spray | Meta-Mood | n = 25 young men (18 to 30 years) | 3.58 units on a scale | Standard Error 0.2 |
| Placebo Spray | Meta-Mood | n = 30 older women (63 to 85 years) | 3.63 units on a scale | Standard Error 0.17 |