Going to Altitude With Anxious-depressive Symptoms

Summary

Introduction: Currently, there is a lack of international guidelines or clinical recommendations for individuals with mental illnesses (i.e., bipolar disorder, posttraumatic stress disorder) going on high altitude sojourns. However, these guidelines would be important considering that mental illnesses are among the most common disorders worldwide and millions of people are hiking at high altitudes in the Alps, being granted easy access up to 3800m by cable cars. Before conceptualizing these guidelines, it seems necessary to study the physiological and psychological effects of ambient pressure changes leading to oxygen deficiency (hypoxia) in individuals with mental illnesses when being exposed to hypoxic conditions. The investigators hypothesize a shift towards negative affective responses and state anxiety as well as increased levels of neurotransmitter precursor amino acids (PHE/TYR and KYN/TRP) in individuals with mental illnesses when being exposed to hypoxic conditions.

Methods and Analysis: The investigators plan to perform a double-blind randomized controlled trial in a safe laboratory environment by using a normobaric hypoxic chamber. Participants suffering from depression and anxiety symptoms will be included as well as age and sex-matched healthy controls. They will attend a six-hour exposure equivalent to 3800m of altitude as well as a six-hour exposure to sham hypoxic conditions. Recruited participants will be screened by the Beck Anxiety and Depression Inventory, the Symptom Checklist (SCL-90) as well as an interview assessment. Affective responses in state anxiety will be assessed before, and during each hour of exposure by using the Feeling Scale (FS), Felt Arousal Scale (FAS), Positive and Negative Affect Schedule (PANAS), State-Anxiety Inventory (STAI) and subjective mental stress levels (Visual Analogue Scale; VAS). Physiological parameters will be assessed by venous blood sampling, pulse oximetry and oxidative stress level measurement before entering the chamber, after three and six hours of exposure. Additionally, symptoms of acute mountain sickness will be assessed by the Lake Louise Score before, after three and six hours of exposure. Follow-up measurements are planned one and seven days after the chamber visit, consisting of venous blood sampling, the Beck Anxiety and Depression Inventory.

A series of univariate analyses of covariance (ANCOVA) for repeated measures will be used to test the three-way (i.e. "group × condition × time") and two-way ("group × condition" and "group × time") interactions. Analyses will be adjusted for possible confounding, by adding age, sex, smoking, prior AMS, and medication status in the models as covariates.

Ethics and dissemination: Ethical approval has been obtained from the ethics committee of the Medical University of Innsbruck (1250/2021).

Conditions

• Hypoxia
• Mental Disorder

Interventions

BIOLOGICAL

Hypoxia

Participants will be randomly assigned to start with the normobaric hypoxia condition or the sham hypoxia condition. They will swap to the other condition during the second visit, which will be executed at least 14 days after the first visit. Each sojourn will last for six hours and participants will reside in the chamber individually. During the six-hour stay, participants will be allowed to move freely within the chamber.

Sponsors & Collaborators

• Medical University Innsbruck

  collaborator OTHER

• Universitaet Innsbruck

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

65 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2023-04-14

Primary Completion

2025-07-15

Completion

2025-12-31

Countries

• Austria

Study Locations