Effects of Altitude-like Cognition Training on Neuroplasticity and Cognitive Functions

NCT ID: NCT06121206

Last Updated: 2025-09-26

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 190 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-02-01
• Study Completion Date: 2025-07-30

Brief Summary

The goal of this clinical trial is to investigate the effects of a three-week altitude-like cognition training intervention in healthy individuals (substudy 1) and symptomatically stable patients with mood disorders (depression or bipolar disorder; substudy 2). This multi-modal intervention consists of an adaptive cognitive training programme that participants complete while they're inside an altitude-training room with 12% O2, corresponding to 4400 meters altitude.

Across substudy 1 and 2, the investigators hypothesize that altitude-like cognition training has a beneficial effect on cognition after three-weeks treatment completion measured with a global cognition composite score (primary outcome measure). Further, the investigators hypothesize that hypoxia and cognition training will yield improved executive functioning after treatment completion and changes in brain activity during working memory in the dorsal prefrontal cortex 4 weeks after treatment completion (secondary outcome measures). In the patient study, the investigators further hypothesize that the intervention will have beneficial effects on daily-life cognition measured in virtual reality (VR) 4 weeks after treatment completion (secondary outcome measure in substudy 2). For exploratory purposes, the study will examine effects on additional measures of cognition, functioning and self-ratings scales (tertiary outcomes).

The investigators will compare the combination of altitude-like hypoxia (12%) and cognitive training with (1) hypoxia with no training, (2) cognitive training under normal oxygen levels (normoxia; 20%), and (3) normoxia with no training in healthy individuals (substudy 1). For patients with mood disorders (substudy 2) the effects of altitude-like hypoxia (12%) and cognitive training are compared to treatment as usual (TAU).

Detailed Description

ALTIBRAIN aims to test a novel model, linking altitude-like oxygen manipulations, endogenous erythropoietin (EPO) in the brain, neuroplasticity and cognition. Specifically, ALTIBRAIN will determine whether upregulation of endogenous brain EPO by altitude-like hypoxia cognition training is a fundamental mechanism of enduring neuroplasticity and long-lasting cognitive improvement in humans. This will be investigated in healthy individuals (substudy 1) and symptomatically stable patients with mood disorders (depression or bipolar disorder; substudy 2).

Substudy 1 involves four intervention groups: (1) altitude-like hypoxia (12%) combined with cognitive training, (2) hypoxia with no training, (3) cognitive training under normoxia (20%), and (4) normoxia with no training. Participants are randomised in blocks of four and undergo interventions in these groups for practical reasons. During the 3-weeks treatment, participants breathe 12% ambient oxygen (≈4400 meters altitude) or normal sea-level oxygen (20%) in a treatment room, 3.5 hours daily, six days per week. On iPads, they perform cognitive training or matched control games without cognitive benefits. Cognitive training is interleaved by short breaks, during which the participants can relax or walk on a treadmill inside the room. Participants undergo cognition assessments in weeks 1 (baseline), 4 and 8 and functional and structural MRI in weeks 1 and 8, when red blood cells are comparable between groups. A subgroup will also undergo PET scanning in week 4.

In substudy 2, patients are randomized to either (1) altitude-like hypoxia (12%) combined with cognitive training, 3.5 hours daily, five-six days per week for three weeks or (2) treatment as usual (TAU). After completed testing, patients in the TAU group undergo the 3-week active intervention, followed by an additional session of neurocognitive testing in the week after treatment completion. All remaining study procedures are identical to substudy 1.

The power calculation was based on the primary hypothesis that altitude-like hypoxia combined with cognitive training produces robust sustained cognitive improvement compared with normoxia and no training. To accommodate for up to a 15% drop-out, we will include 30 participants per group; i.e., 120 healthy individuals and 60 patients to obtain complete data for minimum 26 participants per group, i.e., 104 healthy individuals and 52 patients.

Conditions

Cognitive Impairment; Bipolar Disorder; Depression

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: DOUBLE

Study Groups

Altitude-like hypoxia (12%) combined with cognitive training

Participants breathe 12% ambient oxygen in an altitude-training room, 3.5 hours daily, 5-6 days per week for 3 weeks. On iPads, they perform cognitive training, which is interleaved by short breaks.

Group Type: EXPERIMENTAL

Altitude-like hypoxia (12% O2)

Intervention Type: OTHER

Fresh air with 12% O2, is blown into a sealed 20 m³ room by a 4kW air compressor with a safety-approved system developed by HöhenBalance, Austria. After participants enter the room, the O2 levels will be reduced from 16% to 12% (≈ 4,400 meters altitude) in a 30 minutes lead-in phase. The target O2 level of 12% will be maintained over three hours

Cognitive training

Intervention Type: BEHAVIORAL

The web-based cognitive training (Happy Neuron Pro) is grounded on principles of neuroplasticity-based learning by being intensive, neuroadaptive, engaging and rewarding. The active training involves parametric task adjustment by decreasing stimuli presentation time, increasing working memory load, decreasing time to respond, and increasing the number of non-target items (distractors).

Altitude-like hypoxia (12%) with no training

Participants breathe 12% ambient oxygen in an altitude-training room, 3.5 hours daily, 6 days per week for 3 weeks. On iPads, they perform matched control games without cognitive benefits, which is interleaved by short breaks.

Group Type: ACTIVE_COMPARATOR

Altitude-like hypoxia (12% O2)

Intervention Type: OTHER

Fresh air with 12% O2, is blown into a sealed 20 m³ room by a 4kW air compressor with a safety-approved system developed by HöhenBalance, Austria. After participants enter the room, the O2 levels will be reduced from 16% to 12% (≈ 4,400 meters altitude) in a 30 minutes lead-in phase. The target O2 level of 12% will be maintained over three hours

Sham training

Intervention Type: BEHAVIORAL

Participants in the no training control condition receive computer games similar to Happy Neuron Pro but with low cognitive demand that produce no cognitive benefits. Specifically, this sham procedure involves the exact same stimuli as the active condition but with changes from trial to trial only in the appearance of the tasks.

Normoxia (20%) combined with cognitive training

Participants breathe 20% ambient oxygen in an altitude-training room, 3.5 hours daily, 6 days per week for 3 weeks. On iPads, they perform cognitive training, which is interleaved by short breaks.

Group Type: ACTIVE_COMPARATOR

Normoxia (20% O2)

Intervention Type: OTHER

Fresh air with 20% O2, is blown into a sealed 20 m³ room by a 4kW air compressor with a safety-approved system developed by HöhenBalance, Austria. The target O2 level of 20% will be maintained over 3.5 hours

Cognitive training

Intervention Type: BEHAVIORAL

The web-based cognitive training (Happy Neuron Pro) is grounded on principles of neuroplasticity-based learning by being intensive, neuroadaptive, engaging and rewarding. The active training involves parametric task adjustment by decreasing stimuli presentation time, increasing working memory load, decreasing time to respond, and increasing the number of non-target items (distractors).

Normoxia (20%) combined with no training

Participants breathe 20% ambient oxygen in an altitude-training room, 3.5 hours daily, 6 days per week for 3 weeks. On iPads, they perform matched control games without cognitive benefits, which is interleaved by short breaks.

Group Type: SHAM_COMPARATOR

Normoxia (20% O2)

Intervention Type: OTHER

Fresh air with 20% O2, is blown into a sealed 20 m³ room by a 4kW air compressor with a safety-approved system developed by HöhenBalance, Austria. The target O2 level of 20% will be maintained over 3.5 hours

Sham training

Intervention Type: BEHAVIORAL

Participants in the no training control condition receive computer games similar to Happy Neuron Pro but with low cognitive demand that produce no cognitive benefits. Specifically, this sham procedure involves the exact same stimuli as the active condition but with changes from trial to trial only in the appearance of the tasks.

Treatment as usual

Participants receive no additional care or intervention between baseline and end-of-treatment assessment points.

Group Type: NO_INTERVENTION

No interventions assigned to this group

Interventions

Altitude-like hypoxia (12% O2)

Fresh air with 12% O2, is blown into a sealed 20 m³ room by a 4kW air compressor with a safety-approved system developed by HöhenBalance, Austria. After participants enter the room, the O2 levels will be reduced from 16% to 12% (≈ 4,400 meters altitude) in a 30 minutes lead-in phase. The target O2 level of 12% will be maintained over three hours

Intervention Type: OTHER

Normoxia (20% O2)

Fresh air with 20% O2, is blown into a sealed 20 m³ room by a 4kW air compressor with a safety-approved system developed by HöhenBalance, Austria. The target O2 level of 20% will be maintained over 3.5 hours

Intervention Type: OTHER

Cognitive training

The web-based cognitive training (Happy Neuron Pro) is grounded on principles of neuroplasticity-based learning by being intensive, neuroadaptive, engaging and rewarding. The active training involves parametric task adjustment by decreasing stimuli presentation time, increasing working memory load, decreasing time to respond, and increasing the number of non-target items (distractors).

Intervention Type: BEHAVIORAL

Sham training

Participants in the no training control condition receive computer games similar to Happy Neuron Pro but with low cognitive demand that produce no cognitive benefits. Specifically, this sham procedure involves the exact same stimuli as the active condition but with changes from trial to trial only in the appearance of the tasks.

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• 18-50 years
• No psychiatric history
• Fluency in Danish

• 18-65 years
• International Classification of Diseases (ICD)-10 diagnosis of Bipolar Disorder or depression confirmed with the Schedules for Clinical Assessment in Neuropsychiatry (SCAN)
• Fluency in Danish
• Partial or full remission (defined as a score of ≤14 on the Hamilton Depression Rating Scale 17-items (HDRS-17) and the Young Mania Rating Scale (YMRS)
• Objectively-verified cognitive impairment according to Screen for Cognitive Impairment in Psychiatry (SCIP) and/or self-reported cognitive impairment measured with Cognitive Complaints in Bipolar disorder Rating Assessment (COBRA). For SCIP, their performance must be ≥0.5 standard deviations (SD) below their demographically adjusted expected total SCIP score or on minimum 2 SCIP subtest scores. For COBRA, patients must report substantial cognitive impairment defined as a score ≥14.

Exclusion Criteria

• Schizophrenia or schizoaffective disorder
• Neurological disorder
• Alcohol or substance abuse
• History of serious head trauma
• Previous altitude sickness
• Heart disease
• Diabetes
• Renal failure
• Untreated/insufficiently treated hypertension
• Thromboses or thromboembolic events
• First-degree family with thromboembolic events before age 60
• Pregnancy
• Breastfeeding
• Smoking or use other nicotine products regularly
• BMI>30
• Electroconvulsive therapy (ECT) 3 months prior to participation
• Dyslexia
• Claustrophobia (MRI scans)
• Pacemaker and/or other MRI incompatible metal implants (MRI scans)
• Participation in experiments with radioactivity (>10 mSv) within the last year (PET scans)
• Significant occupational exposure to radioactivity (PET scans)
• Medication incompatible with study aims (e.g., SV2A binding agents; PET scans)

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 65 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

European Research Council

OTHER

Sponsor Role: collaborator

University of Copenhagen

OTHER

Sponsor Role: collaborator

Rigshospitalet, Denmark

OTHER

Sponsor Role: collaborator

Mental Health Services in the Capital Region, Denmark

OTHER

Sponsor Role: lead

Responsible Party

Kamilla Woznica Miskowiak

Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Kamilla W Miskowiak, DMSc, DPhil

Role: PRINCIPAL_INVESTIGATOR

Mental Health Services in the Capital Region, Denmark

Locations

Neurocognition and Emotion in Affective Disorders (NEAD) Centre, University of Copenhagen and Psychiatric Centre Copenhagen, Frederiksberg hospital

Copenhagen, Capital Region of Copenhagen, Denmark

Countries

Denmark

References

Miskowiak KW, Damgaard V, Schandorff JM, Macoveanu J, Knudsen GM, Johansen A, Plaven-Sigray P, Svarer C, Fussing CB, Cramer K, Jorgensen MB, Kessing LV, Ehrenreich H. Effects of cognitive training under hypoxia on cognitive proficiency and neuroplasticity in remitted patients with mood disorders and healthy individuals: ALTIBRAIN study protocol for a randomized controlled trial. Trials. 2024 Oct 3;25(1):648. doi: 10.1186/s13063-024-08463-5.

Reference Type: DERIVED

PMID: 39363230 (View on PubMed)

Other Identifiers

P-2022-354

Identifier Type: REGISTRY

Identifier Source: secondary_id

H-22028111

Identifier Type: -

Identifier Source: org_study_id