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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
106
single dose of 24 IU oxytocin, self-administered intranasally (IN)
single dose of 24 IU placebo (same solution as oxytocin spray but without oxytocin), self-administered intranasally (IN)
University of Florida
Gainesville, Florida, United States
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
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
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
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