The Effect of Inspiratory Muscle Training on Cognitive Functions, Cerebral Oxygenation, and Neurotrophic Factor Level in Patients With Obstructive Sleep Apnea Syndrome

NCT07329049 | Not Yet Recruiting

• 1 other identifier: 2025/1362
• Study Type: interventional
• Target: 42
• Locations: 0 countries
• Sites: N/A

Brief Summary

The aim of this clinical study is to examine the effect of an 8-week training program applied to the respiratory muscles that enable breathing in individuals with obstructive sleep apnea syndrome on cognitive functions, oxygenation of brain tissue, and the brain's healing and adaptation processes. The main questions it aims to answer are: Does respiratory muscle training applied to individuals with obstructive sleep apnea syndrome have a beneficial effect on cognitive functions? Does respiratory muscle training applied to individuals with obstructive sleep apnea syndrome have a beneficial effect on brain oxygenation? Does respiratory muscle training applied to individuals with obstructive sleep apnea syndrome have a beneficial effect on the brain's healing and adaptation processes? A total of 42 individuals with obstructive sleep apnea syndrome will be included in the study. Researchers will compare the effectiveness of respiratory muscle training on individuals with obstructive sleep apnea syndrome by comparing the respiratory muscle training intervention with placebo (low-intensity respiratory muscle training) and usual care. At the beginning of the study, participants' demographic data will be recorded, they will be assessed, their blood will be drawn, and they will be asked to complete a questionnaire. Participants will be given an information brochure and a weekly follow-up form in addition to the necessary medical treatment. Participants will receive the necessary medical treatment for 8 weeks, fill out the follow-up form provided every day and send it to the researcher once a week, perform inspiratory muscle training exercises for 8 weeks, and meet face-to-face with the researcher once a week. The follow-up form will be checked every week. All assessments will be repeated at the end of the study.

Conditions

Obstructive Sleep Apnea Syndrome (OSAS)

Keywords

obstructive sleep apnea syndrome; cognitive function; brain oxygenation; brain-derived neurotrophic factor

Outcome Measures

Primary Outcomes (7)

• Digit Span Test

  A subscale of the WAIS-R, this test aims to measure an individual's level of attention. It is administered in two parts using forward and backward sequencing of numbers. Numbers between 1 and 9 are presented to the individual in a random order, and the individual is asked to repeat them in the same sequence. The test is repeated until the individual correctly repeats the sequence twice in a row or until 12 repetitions are reached. In the evaluation of the test, 2 points are awarded for each correct sequence and 1 point for each sequence with one error. Since there are a total of 12 attempts, even if the individual correctly repeats the sequence twice, 2 points are added for each additional attempt required to reach 12 attempts. The maximum possible score on the test is 24. The test will be administered on the first and last days of treatment.

  Baseline and 8 weeks

• Montreal Cognitive Assessment Scale

  The Turkish version will be used to assess individuals' cognitive function. This scale, which takes approximately 10 minutes to administer, will be administered face-to-face with individuals. The maximum score that can be obtained on the scale is 30. One point is added for individuals with less than 12 years of education. The cutoff value for the scale has been set at \<23. The MBDÖ assesses 8 different cognitive function areas: memory, executive functions, visual construction skills, concentration, language, orientation, calculation, and attention. The first and last days of treatment will be evaluated.

  Baseline and 8 weeks

• Oktem Verbal Memory Processes Test

  The Turkish adaptation of the Verbal Memory Processes Test, developed by Rey in 1964, was created by Oget Oktem.It assesses verbal memory processes such as auditory-verbal learning, memory recording, recall, and recognition.There is a recognition list with 15 words on the front and 45 words on the back.The target word list on the front is repeated 10 times, and after each repetition, the individual is asked to say the words they have learned, which are recorded, and their score is tallied.This score is the Learning Score Dimension. After a 30-40 minute interval, the individual is asked to recall the target words.The score obtained here is the Spontaneous Recall Dimension score. For words that cannot be recalled, three recognition words consisting of one phonemic and one semantic distractor from the recognition list on the back side will be read, and then the individual will be asked whether the word is found in the target word list.The score obtained is the Recognit Dimension Score.

  Baseline and 8 weeks

• Stroop Test

  This test measures the ability to inhibit inappropriate responses in executive functions, provides information about selective attention under distracting conditions, and demonstrates frontal lobe functions in the brain.Before starting the test, the person is taught which buttons to press for 4 colors (1=yellow, 2=blue, 3=green, and 4=red).Then, the three-stage test begins: In the first stage, the person must identify the color of 24 colored circles appearing sequentially on the screen and press the correct key.In the second stage, the person must recognize only the color in which 24 neutral words of different colors appear sequentially on the screen and press the correct key.The third stage involves the most demanding task: words with color names written in different colors are displayed in sequence on the screen (for ex., the word "red" may be written in blue).The person is asked to focus on the color in which the word is written, not what the word says, and press the correct button

  Baseline and 8 weeks

• Functional near-infrared spectroscopy (fNIRS)

  Changes in blood flow in the prefrontal cortex related to executive functions will be assessed using functional near-infrared spectroscopy during a verbal fluency task. During the application, a total of 18 optodes will be placed on the dorsolateral prefrontal cortex (DLPFC). Each source/detector pair will be placed approximately 3 centimeters apart in accordance with the EEG 10-20 system. These optodes will be arranged into 24 channels using a soft neoprene cap. The phonemic verbal fluency test will be administered while the individual is wearing the cap, and data from the measurement during the test will be collected using the fNIRS control box and the connected computer. Thus, while the phonemic verbal fluency test is being administered, changes in the concentration of oxyhemoglobin and deoxyhemoglobin in the prefrontal cortex will be recorded using the fNIRS device.

  Baseline and 8 weeks

• Verbal fluency test

  This test is used to evaluate various executive functions such as attention, semantic memory, information processing speed, task initiation, complex attention, and inhibition of inappropriate responses. The headset will be placed on the individual's head and the optode placement will be adjusted. Recording will then be performed using fNIRS, and a block design consisting of a total of three blocks for the letters 'K, A, S' will be used during the test. Each block covers a total of 140 seconds, consisting of a 10-second pre-rest period, a 60-second activation period, and a 70-second post-rest period. During the activation period, participants will be asked to generate as many words as possible beginning with a specific initial letter. Words should not be proper nouns, repetitions, or numbers. Digital recordings will be made, and the words spoken, their times of utterance, the number of incorrectly spoken words, and the number of repeated words will be recorded. The phonemic fluency sc

  Baseline and 8 weeks

• Brain-Derived Neurotrophic Factor

  Blood samples will be collected in biochemistry tubes before the first session and after the final session of the 8-week intervention. After 10 minutes of centrifugation, serum will be obtained and stored at -80°C until analysis. BDNF, a key neurotrophic factor for neuronal survival, differentiation, and synaptic plasticity, will be measured using the Human Free BDNF Quantikine ELISA Kit (R\&D Systems). The method is based on a sandwich ELISA principle to quantify serum BDNF levels. Venous blood is allowed to clot for 30-60 minutes, centrifuged at 1500-3000 rpm for 10-15 minutes, and stored at -80°C. Before analysis, samples are thawed and processed according to the kit protocol. After incubation, washing, and substrate steps, absorbance is read at 450 nm, and BDNF concentration is calculated from the standard curve. Duplicate measurements are recommended for reliability.

  Baseline and 8 weeks

Secondary Outcomes (11)

• Respiratory muscle strength

  Baseline and 8 weeks

• Respiratory muscle endurance

  Baseline and 8 weeks

• Respiratory function test

  Baseline and 8 weeks

• Increasing Speed Shuttle Walk Test

  Baseline and 8 weeks

• Biochemical analyses: Oxidative Stress

  Baseline and 8 weeks

Study Arms (3)

Control Group

OTHER

Individuals will receive standard medical treatment. They will be informed about their illnesses, what they need to do, and what they need to be mindful of. A disease-specific informational brochure and a follow-up form will be provided.

Other: Usual Care

Placebo IMT group

SHAM COMPARATOR

In addition to the control group, individuals will undergo low-resistance IMT at 15% of maximum inspiratory pressure every day for 8 weeks.

Device: Placebo inspiratory muscle training

IMT Group

ACTIVE COMPARATOR

Individuals will undergo IMT for 8 weeks in addition to the control group. Resistance will start at 50% of MIP and be gradually increased to 75%.

Device: inspiratory muscle training

Interventions

inspiratory muscle training DEVICE

In addition to the control group, IMT will be applied for 8 weeks, 7 days a week, twice a day for 15 minutes (30 breaths/3 sets/1-minute break between sets).The intensity of the training provided in IMT will be gradually increased over the 8 weeks.Before starting the training, patients' mouth pressure (MIP) will be measured and the training workload will be determined. During the first 2 weeks of training, 50% of MIP will be applied as the workload, 60% of MIP during weeks 3 and 4, and 75% of MIP during the last 4 weeks.During weekly face-to-face sessions, patients' new MIP values will be measured to determine the new workload.Patients will be given treatment diaries and asked to mark the sessions they have completed.They will be asked to bring these diaries to the physiotherapist once a week during face-to-face sessions. Additionally, during these sessions, patients' use of the IMT device will be checked, and if any errors are detected, device usage will be re-explained.

IMT Group

Placebo inspiratory muscle training DEVICE

In addition to the control group, inspiratory muscle training at 15% of MIP will be administered twice daily for 15 minutes (30 breaths/3 sets/1-minute rest between sets) for 7 days a week over an 8-week period. Patients will be given treatment diaries and asked to mark their sessions and send these diaries to the physical therapist once a week.

Placebo IMT group

Usual Care OTHER

Individuals will receive standard medical treatment. They will be informed about their illnesses, what they need to do, and what they need to be mindful of. A disease-specific informational brochure and a follow-up form will be provided.

Control Group

Eligibility Criteria

• Age: 18 Years - 60 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Patients diagnosed with moderate OSA using polysomnography
• Aged 18-60
• Not using non-invasive mechanical ventilation (NIMV)
• General health status is stable (The participant does not have an acute -cardiovascular, respiratory, metabolic, or neurological disease; has not experienced a condition requiring hospitalization in the last three months)
• No mental problems that would interfere with cooperation

You may not qualify if:

• History of oropharyngeal surgery
• Presence of any neurological, psychological, or cardiac disease
• BMI ≥40 kg/m²
• Presence of hypothyroidism, uncontrolled hypertension, and diabetes
• Having severe obstructive nasal disease
• Being pregnant
• Having cognitive problems
• Having overlap syndrome
• Using drugs, alcohol, sedatives, and hypnotic medications
• Exercise group participants with \<75% attendance at training sessions
• Failure to attend sessions for 2 consecutive weeks during the treatment period

Sponsors & Collaborators

• Istinye University: lead

Related Publications (4)

• Cheng YY, Lin SY, Hsu CY, Fu PK. Respiratory Muscle Training Can Improve Cognition, Lung Function, and Diaphragmatic Thickness Fraction in Male and Non-Obese Patients with Chronic Obstructive Pulmonary Disease: A Prospective Study. J Pers Med. 2022 Mar 16;12(3):475. doi: 10.3390/jpm12030475.

  PMID: 35330474 BACKGROUND

• Ferreira L, Tanaka K, Santos-Galduroz RF, Galduroz JC. Respiratory training as strategy to prevent cognitive decline in aging: a randomized controlled trial. Clin Interv Aging. 2015 Mar 20;10:593-603. doi: 10.2147/CIA.S79560. eCollection 2015.

  PMID: 25848235 BACKGROUND

• Souza AKF, Dornelas de Andrade A, de Medeiros AIC, de Aguiar MIR, Rocha TDS, Pedrosa RP, de Lima AMJ. Effectiveness of inspiratory muscle training on sleep and functional capacity to exercise in obstructive sleep apnea: a randomized controlled trial. Sleep Breath. 2018 Sep;22(3):631-639. doi: 10.1007/s11325-017-1591-5. Epub 2017 Nov 9.

  PMID: 29124630 BACKGROUND

• Nobrega-Junior JCN, Dornelas de Andrade A, de Andrade EAM, Andrade MDA, Ribeiro ASV, Pedrosa RP, Ferreira APL, de Lima AMJ. Inspiratory Muscle Training in the Severity of Obstructive Sleep Apnea, Sleep Quality and Excessive Daytime Sleepiness: A Placebo-Controlled, Randomized Trial. Nat Sci Sleep. 2020 Dec 2;12:1105-1113. doi: 10.2147/NSS.S269360. eCollection 2020.

  PMID: 33293881 BACKGROUND

MeSH Terms

Conditions

Sleep Apnea, Obstructive

Condition Hierarchy (Ancestors)

Sleep Apnea Syndromes; Apnea; Respiration Disorders; Respiratory Tract Diseases; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Wake Disorders; Nervous System Diseases

Central Study Contacts

Feyza MERAKLI

CONTACT

+905427685223; feyzamrkl@gmail.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal investigator

Study Record Dates

• First Submitted: December 12, 2025
• First Posted: January 9, 2026
• Study Start: January 1, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): September 1, 2027
• Last Updated: January 9, 2026

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will not share