The Mechanisms Underlying the Antidepressant Effects of Physical Activity
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- Depression
- Sponsor
- University College, London
- Enrollment
- 250
- Locations
- 1
- Primary Endpoint
- Patient Health Questionnaire-9 score
- Status
- Recruiting
- Last Updated
- 7 months ago
Overview
Brief Summary
It is well established that any level of physical activity can help prevent and treat depression, with more strenuous activity having a greater effect. Understanding the mechanisms driving this antidepressant effect is important because it could allow exercise programmes to be made more effective, accessible, and targeted. Such knowledge could contribute to social prescribing, increasingly a priority for mental healthcare. Importantly, physical activity is highly scalable, low cost, well suited to early intervention, and has beneficial impacts on physical health co-morbidities. This trial may provide initial indications of whether there are sub-groups of depressed individuals who are particularly likely to benefit from physical activity, lead to strategies to personalise physical activity prescription based on motivational factors, and pave the way for augmentative approaches, for example combining physical activity with psychological interventions.
To date the mechanisms driving the antidepressant effects of physical activity in humans are poorly understood. Building on links between depressive symptoms, reward processing and dopamine, plus evidence from animal studies that physical activity is anti-inflammatory and boosts both dopamine and reward processing, the overarching aim of this trial is to understand the mechanisms underlying the effects of physical activity in depression, focusing on the concept of motivation.
The key objective is to conduct a randomised controlled trial (RCT) in N=250 depressed participants comparing aerobic exercise to a stretching/relaxation control condition, examining a range of mechanistic factors. The proposed trial will examine the impact of physical activity at multiple, linked potential levels of explanation: (1) immune-metabolic markers; (2) dopamine synthesis capacity; (3) activation in the brain's reward and effort processing circuitry;(4) effort-based decision making incorporating computational analysis; and (5) symptom networks based on fine-grained, daily measurements.
Detailed Description
The primary objective is to conduct a randomised controlled trial (RCT) in N=250 depressed participants comparing aerobic exercise to a stretching/relaxation control condition, examining effects on a range of potential clinical and mechanistic factors: depressive symptoms; immune-metabolic function; activation in the brain's reward and effort processing circuitry using functional magnetic resonance imaging (fMRI); cognitive tasks, focusing on reward processing; and a subset (approximately one-third) of participants will complete L-6-\[18F\] fluoro-3,4-dihydroxyphenylalnine (18F-DOPA) positron emission tomography (PET). The secondary objectives are to assess: (1) the degree to which changes in the mechanistic factors are related to changes in interest-activity symptoms of depression resulting from aerobic exercise; (2) whether baseline mechanistic or clinical factors are associated with symptomatic improvement measured by symptom questionnaires following the exercise intervention; (3) whether aerobic exercise-induced changes in the brain circuits underlying cognitive control overlap with those implicated in motivation. The trial will use an RCT design, with depressed participants randomised to eight weeks of either 45 minutes aerobic exercise of moderate-to-vigorous intensity activity (experimental group: three times per week, N=125) or 45 minutes of non-aerobic stretching/guided relaxation (control group: three times per week, N=125). The target sample size following expected attrition is N\~105 per arm. Participants will complete the trial in staggered cohorts, with no more than six participants per class. Blood and saliva samples will be taken before the intervention at baseline (between weeks -1 and 0), mid-intervention (week 3 and week 4), and post-intervention (week 9 to week 14) visits, to assess changes in immune-metabolic markers. Blood and saliva samples will also be collected at baseline and post-intervention from approximately 30 healthy controls. Functional neuroimaging during effort-based decision-making and cognitive control will be taken at baseline and post-intervention. The same functional neuroimaging measures will also be collected at baseline and post-intervention from approximately 30 healthy controls. Cognitive assessments will be completed online at baseline, every other week during the intervention (week 1, week 3, week 5, week 7), and post-intervention. The same cognitive assessments will also be collected at identical time-windows from approximately 30 healthy controls. Questionnaire assessments will be completed online at baseline, every other week (week 2, week 4, week 6) and post-intervention (week 9 to 14). The same questionnaire assessments will be collected at baseline and post-intervention from approximately 30 healthy controls. Accelerometers will measure physical activity continuously at baseline and during the intervention. Fitness testing will provide a measure of cardiovascular fitness at baseline and post-intervention visits. Daily depressive symptoms will be recorded using abbreviated scales using the Neureka smartphone app throughout the intervention. Three-monthly follow up of symptoms/cognition from baseline over six months will assess the durability of effects (week 21 and week 33). In a subset of participants, approximately one-third of the participants will also complete a positron emission tomography (PET) scan pre-randomisation and at a visit during weeks 4-9 to 14, to assess dopamine synthesis capacity. The same PET scan will also be collected from approximately 30 healthy controls.
Investigators
Eligibility Criteria
Inclusion Criteria
- Not provided
Exclusion Criteria
- Not provided
Outcomes
Primary Outcomes
Patient Health Questionnaire-9 score
Time Frame: Post-intervention (week 9 to week 14)
Depression symptoms will be measured using the Patient Health Questionnaire-9 (PHQ-9). Minimum score is 0, maximum score is 27. Higher scores mean a worse outcome.
Secondary Outcomes
- Physical activity(Baseline assessment period (between weeks -1 and 0) to post-intervention (week 9 to week 14), and follow-up (weeks 21 and 33))
- Aerobic capacity: CPET(Baseline (between weeks -1 and 0) and post-intervention (week 9 to week 14))
- Ecological Momentary Assessment(Baseline assessment period (between weeks -1 and 0) to post-intervention (week 9 to week 14))
- Inflammatory response (cytokines)(Baseline (between weeks -1 and 0), mid-intervention (week 3 or week 4), and post-intervention (week 9 to week 14))
- Inflammatory response (genetic markers)(Baseline (between weeks -1 and 0), mid-intervention (week 3 or week 4), and post-intervention (week 9 to week 14))
- Inflammatory response (flow cytometry immunophenotype)(Baseline (between weeks -1 and 0), mid-intervention (week 3 or week 4), and post-intervention (week 9 to week 14))
- Neuroendocrine system(Baseline (between weeks -1 and 0), mid-intervention (week 3 or week 4), and post-intervention (week 9 to week 14))
- Metabolic function(Baseline (between weeks -1 and 0), mid-intervention (week 3 or week 4), and post-intervention (week 9 to week 14))
- Dopamine synthesis capacity(Baseline (between weeks -1 and 0) and post-intervention (week 4-9 to week 14))
- Functional magnetic resonance imaging (fMRI) during cognitive tasks(Baseline (between weeks -1 and 0) and post-intervention (week 9 to week 14))
- Online cognitive tasks(During every other week of the intervention (weeks -1/0, week 1, week 3, week 5, week 7, week 9 to week 14))
- Depression symptoms(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6))
- Anxiety (GAD7 score)(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Anxiety (STAI score)(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Anhedonia (SHAPS score)(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Anhedonia (DARS score)(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Apathy(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Fatigue(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Cognitive impairment(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Self-efficacy(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Self-esteem(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))
- Sleep quality(During every other week of the intervention (weeks -1/0, week 2, week 4, week 6, week 9 to week 14))