Acute Aerobic Exercise and Neuroplasticity in Depression
Condition: Depression; Depressive Disorder
MeSH terms: Depression; Depressive Disorder
Study type: Interventional

Summary: 
      Depression is associated with a disruption in the mechanisms that regulate neuroplasticity.
      Effective treatment and rehabilitation of depression, and other neurological and
      neuropsychiatric disorders, relies on neuroplasticity. Thus, identifying therapies that
      enhance neuroplasticity (neuroplastic adaptation) are vital in the comprehensive treatment of
      depression. Aerobic exercise training has been demonstrated to have antidepressant properties
      and single bouts of aerobic exercise may provide short-term improvements in affective states
      in depression. Furthermore, acute aerobic exercise may enhance the response to known
      neuroplasticity-inducing paradigms. However, it is unclear if aerobic exercise can influence
      neuroplasticity in depression and the neurobiological mechanisms underlying acute
      neuroplastic changes are not well understood in depressed and healthy cohorts. Thus, the
      purpose of this project is to examine the acute effects of aerobic exercise on neuroplastic,
      neurobiological, and mood indices of depression.
    

Detailed description: 
      The investigators will determine the effects of exercising at two different intensities
      (compared to a control non-exercise condition) on neuroplastic potential in depressed and
      non-depressed subjects. To accomplish this aim, the investigators will have subjects ride a
      cycle ergometer at intensities set to elicit 35% (low) and 70% (high) of heart rate reserve
      (((220 - age) - resting heart rate) x 35% or 70%) + resting heart rate). Prior to, and
      immediately after exercise participants will have their neuroplastic potential tested via
      transcranial magnetic stimulation (TMS), blood specimens sampled, and mood changes assessed
      (methods detailed below). These assessments will occur at these time points and then every 15
      minutes for 1 hour after exercise.

      Neuroplastic potential will be assessed using TMS. TMS-induced motor evoked potentials
      (MEP's) will be recorded from the abductor pollicis brevis as a way to measure changes in the
      excitability of the corticospinal tract in response to exercise and paired associative
      stimulation. Serum brain-derived neurotrophic factor (BDNF) and cortisol levels will be
      obtained through blood specimen samples in order to examine the potential exercise-induced
      changes in known stress- and neuroplasticity-related biomarkers. Mood and affect will be
      surveyed using the Activation-Deactivation Checklist (AD ACL), feeling scale (FS), and felt
      arousal scale (FAS). These measures will permit the assessment of exercise-induced changes in
      mood and affect.
    

Intervention name(s): Aerobic Exercise; Paired Associative Stimulation
Intervention type(s): Behavioral; Device
Intervention description(s): Aerobic exercise will be performed on a stationary cycle ergometer for 15 minutes at an intensity of 35% heart rate reserve or 70% heart rate reserve. During the control condition the participant will remain seated on the stationary cycle for 15 minutes and will not perform exercise.; After aerobic exercise participants will receive a paired associative stimulation (PAS) paradigm. PAS consists of paired brain and peripheral nerve stimuli. Participants will receive 200 paired stimuli. Peripheral nerve stimulation will be delivered to the median nerve at the level of the wrist via electrical stimulation at 300% perceptual threshold. Brain stimulation will be delivered via transcranial magnetic stimulation (TMS) over the hand knob of the motor cortex at an intensity that elicits a 1mV response in the contralateral abductor pollicis brevis muscle. During each paired stimulation, peripheral nerve stimulation will precede the TMS stimulation by 25ms.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Depression; Depressive Disorder; Exercise; Neuroplasticity; Non-invasive brain stimulation; Healthy Control