Anxiety disorders commonly begin during adolescence, and are characterized by deficits in the ability to inhibit or extinguish pathological fear. Recent research has provided new understanding of how fear is learned and can be regulated in the adolescent brain, and how the endocannabinoid system shapes these processes; however, these advances have not yet translated into improved therapeutic outcomes for adolescents with anxiety. This study will test whether a behavioral intervention, acute exercise, can help to improve fear regulation by enhancing brain activity and endocannabinoid signaling. This line of research may ultimately lead to more effect treatments for adolescent anxiety, and to new preventive strategies for at-risk youth.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
174
Participants randomized to the active (moderate intensity) exercise condition will complete a 3-minute warm-up at low speed on a treadmill. Speed and incline will be increased in 3-minute increments until moderate-intensity exercise, defined as participants staying within a zone of 60-80% AAMHR with the target being to attain and maintain 70-75% AAMHR while briskly walking and/or jogging depending on current fitness status, is reached for a total of 30 min.
Tolan Park Medical Building
Detroit, Michigan, United States
RECRUITINGSkin Conductance Responding (SCR)
To compare the effects of acute moderate-intensity exercise (vs. sedentary control) on extinction recall, the investigators will place three electrodes on participant's left hand to acquire SCR data using a BIOPAC MP160 Data Acquisition System (BIOPAC Systems, Inc.).
Time frame: Throughout study completion (3 days)
Unconditioned Stimulus (US) Expectancy Ratings
US Expectancy Ratings will be measured during fear learning, extinction, and recall tasks
Time frame: Throughout study completion (3 days)
Fear extinction neural circuitry: Functional activation and coupling
MRI eligible only: fMRI blood-oxygen-level-dependent (BOLD) response will be measured across the entire brain during a test of extinction recall. The investigators will focus on response in the hippocampus and ventromedial prefrontal cortex activation and coupling (gPPI) during recall (CS+E\>CS+U).
Time frame: Neuroimaging will occur during the fear extinction recall phase on Day 3
Endocannabinoid (eCB) Concentrations
Plasma and saliva samples will be collected immediately before and after exercise or sedentary control condition. Samples will be analyzed using liquid chromatography-mass spectrometry to quantify concentrations of eCBs.
Time frame: eCB concentrations will be measured in plasma and saliva immediately before and after the exercise or control condition on Day 2
Fear Ratings
Fear ratings to each CS will be captured at the beginning, middle, and end of each phase, using a response pad and a 1-5 visual analog scale (1 = not scary at all, 5 = very scary).
Time frame: Throughout study completion (3 days)
Approach/Avoidance Behavior
The investigators will quantify forward-to-backward response pad distance in virtual meters from the conditioned stimulus.
Time frame: Throughout study completion (3 days)
Amygdala response during extinction recall
MRI Eligible Only: fMRI blood-oxygen-level-dependent (BOLD) response will be measured across the entire brain during a test of extinction recall. A secondary region of interest is amygdala response during recall (CS+E\>CS+U).
Time frame: Neuroimaging will occur during the fear extinction recall phase on Day 3
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