None listed
Conditions
Brief summary
Cognition is required so that individuals can make decisions, communicate, think, analyse and move on a daily basis. Patients with chronic obstructive pulmonary disease (COPD) have impaired cognition compared to age matched healthy controls and this is associated with increased mortality and disability (Wen et al. 2018). However, the mechanisms for this cognitive dysfunction remain poorly understood. Several studies have also reported that a reduced brain (cerebral) blood flow can lead to cognitive dysfunction and patients with COPD also have a reduced brain blood flow compared to age matched healthy controls (Beaudin et al. 2017). This finding suggests that the impaired cognition observed in patients with COPD may be due to a reduction in brain blood flow. However, this hypothesis has not been tested. Patients with COPD experience airway obstruction which loads the respiratory muscles and increases the work of breathing. Inspiratory loaded breathing required healthy individuals to breathe through a narrow tube and increases the work of breathing and replicates an exacerbation of COPD. This model of airway obstruction can be used to replicate COPD in healthy young individuals and investigate the effects of loaded breathing on cognition and brain blood flow. The aim of the study is to investigate the effects of inspiratory loaded breathing on cerebrovascular blood flow and cognition in healthy young adults. We will test the hypothesis that inspiratory loaded breathing reduces cerebrovascular blood flow and cognition.
Interventions
The study will be a randomised controlled design. Participants will attend the laboratory for two visits that will each last 2 hours. Visits will be separated by a minimum of 48 h and a maximum of 1 week. The first visit will be a screening and familiarisation session. During the visit, participants will have height, body mass and pulmonary function measured. Participants will then be familiarised with the following 4 experimental conditions:
Control (unloaded breathing)
Control (unloaded brea
The study will be a randomised controlled design. Participants will attend the laboratory for two visits that will each last 2 hours. Visits will be separated by a minimum of 48 h and a maximum of 1 week. The first visit will be a screening and familiarisation session. During the visit, participants will have height, body mass and pulmonary function measured. Participants will then be familiarised with the following 4 experimental conditions: Control (unloaded breathing) Control (unloaded breathing) + cognitive testing Inspiratory loaded breathing Inspiratory loaded breathing + cognitive testing During the second visit, participants will repeat the 4 experimental conditions. These will be undertaken in random order and there will be a 5 min washout period between conditions. Each condition will be preceded and followed by 3 min of rest and recover. Each condition will last 10 min. During the experimental conditions, participants will breathe thorough a pressure-threshold loading device. Participants will be seated with their feet and back supported. The pressure-threshold loading device will be placed on a table and its height adjusted so the participant can reach the mouthpiece with their head and neck in a neutral alignment. Adjustable weights will be attached to the plunger with an inspiratory threshold load that has to be met in order for the participant to inspire. No weights will be added for the control conditions. Weights corresponding to a threshold pressure of 70% of the participants maximal inspiratory pressure will be added for the loaded breathing conditions. Breathing frequency will be set to 15 breaths/min and inspiratory duty cycle (ratio of inspiratory contraction time to total respiratory cycle duration) at 0.7. A metronome will be used to control breathing pattern. Target inspiratory mouth pressure will be displayed on a computer screen to provide continuous visual feedback. Before and after the experimental conditions, 3 min of rest and recovery data will be collected. At minute 4 of the experimental conditions, participants will undertake the Trail Making Task Parts A and B which assesses central executive function delivered using an iPad (6th generation, Apple Inc, Cupertino, CA, USA). The duration of this cognitive test is approximately 1 min. Transcranial Doppler ultrasonography (TCD; DopplerBox X; Compumedics DWL, Singen, Germany) will be used to measure cerebrovascular haemodynamics. Heart rate and arterial blood pressure will be measured on a continuous beat-to-beat basis using finger photoplethysmography (Human NIBP controller; AD Instruments, Bella Vista, NSW, Australia) placed on the middle finger of the nondominant hand and supported on a front table positioned at the heart level. Testing will be undertaken by the primary investigator Dr Dean Mills who holds a PhD in respiratory physiology and has 10 years of experience in the area. Testing will be delivered face to face at the University of Southern Queensland, Sport and Exercise Laboratory, Ipswich, QLD.
Sponsors
University of Southern Queensland
Study design
Allocation
Randomised controlled trial
Intervention model
Crossover
Primary purpose
Prevention
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
Apparently healthy, and free of known disease and/or signs or symptoms of disease..
Exclusion criteria
Current tobacco or electronic cigarette smoker; history or current symptoms of cardiopulmonary disease; contraindications to respiratory testing; and body mass index <18.5 or >30 kg/m2.
Outcome results
None listed