Do acute mountain sickness and psychiatric disorders show overlapping symptoms?

The Lake Louise Score (LLS) is a common tool for diagnosing acute mountain sickness (AMS) after a recent gain in altitude. Required symptoms (headache, dizziness, fatigue or gastrointestinal symptoms) are unspecific, subjective and not detectable by physiological parameters. (Talks et al., 2022; Boos et al., 2018) This study aimed to enhance present knowledge concerning the impact of mental health on LLS. In a cross-sectional questionnaire study, we assessed 3 groups: 100 inpatients (Ward for psychosomatic medicine – Innsbruck, PSY), 73 mentally healthy individuals (Innsbruck, Austria at an altitude of 570 m, CO) and 223 mountaineers in Nepal (Pheriche 4,371 m and Dingboche 4,410 m, NEPAL). Beside social demographics and LLS 2018 (cutoff for LLS-positivity: LLS ≥ 3 including at least 1 point for headache), we examined symptoms of anxiety (Zung Self-Rating Anxiety Scale [SAS], General Anxiety Disorder Questionnaire 7 [GAD-7]), affective states (International Positive and Negative Affect Schedule Short form [I-PANAS-SF]) and sleep (Insomnia Severity Index [ISI]). In this preliminary analysis, the average age was 39 ± 16 years in PSY, 34 ± 16 years in CO and 40 ± 14 years in NEPAL. Gender distribution showed greater portion of women in PSY and CO (PSY: 72% female 24% male 3% non-binary, CO: 64% female 36% male) contrary to NEPAL (36% female 64% male). At sea level, 67% scored LLS-positive in PSY and 12% in CO (Fishers exact test, p < 0.001). In NEPAL 25% met AMS-criteria by LLS. CO and NEPAL score significantly lower in LLS than PSY (ANOVA: diff = -3.70, p < 0.0001; diff = -3.68, p < 0.0001, respectively). PSY and CO showed significant weak to moderate correlations (Spearman-Rho, p < 0.001) of anxiety (SAS, GAD), affective states (I-PANAS-SF) and sleep impairment (ISI) with LLS-sum. NEPAL showed significant very-weak to weak correlations of insomnia, anxiety and negative affect with LLS-sum. Using logistic regression analysis (Figure 1), higher odds of LLS-positivity are significantly associated with insomnia and anxiety (ISI, SAS) in PSY, with anxiety in CO (SAS) and insomnia and negative affect in NEPAL. While of course a recent gain in altitude is a prerequisite for the diagnosis of AMS this study shows that patients with pre-existing mental illness at low altitude score more frequently false-positive on the LLS than a mentally healthy cohort. Symptoms of anxiety, negative affect and sleep disturbance can affect the AMS-defining questionnaire of LLS both at sea level and at high altitude. There is still uncertainty on a possible common pathophysiological pathway of psychiatric diseases and AMS since there is no Gold Standard in diagnosing AMS. Concerning (well-)established risk-factors for AMS like speed of ascent (Berger et al., 2023) and female sex (Hou et al., 2019), we see no evident data. The data presented here suggest that strength of expression of negative affect can cause positive LLS scoring. Acute mountain sickness and psychiatric disorders show overlapping symptoms at sea level. At high altitudes, negative affect seems to be a possible cause for the development of AMS. Further research focus should be placed on mountaineers in high altitude with psychiatric disorders and their mental state. References Berger, M. M., Hüsing, A., Niessen, N., Schiefer, L. M., Schneider, M., Bärtsch, P., & Jöckel, K. H. (2023). Prevalence and knowledge about acute mountain sickness in the Western Alps. PLoS ONE, 18(9), Article e0291060. https://doi.org/10.1371/journal.pone.0291060 Boos, C. J., Bass, M., O’Hara, J. P., Vincent, E., Mellor, A., Sevier, L., Abdul-Razakq, H., Cooke, M., Barlow, M., & Woods, D. R. (2018). The relationship between anxiety and acute mountain sickness. PLoS ONE, 13(6), Article e0197147. https://doi.org/10.1371/journal.pone.0197147 Hou, Y. P., Wu, J. L., Tan, C., Chen, Y., Guo, R., & Luo, Y. J. (2019). Sex-based differences in the prevalence of acute mountain sickness: A meta-analysis. Military Medical Research, 6, Article 38. https://doi.org/10.1186/s40779-019-0228-3 Talks, B. J., Campbell, C., Larcombe, S. J., Marlow, L., Finnegan, S. L., Lewis, C. T., Lucas, S. J. E., Harrison, O. K., & Pattinson, K. T. S. (2022). Baseline psychological traits contribute to Lake Louise Acute Mountain Sickness score at high altitude. High Altitude Medicine & Biology, 23(1), 69–77. https://doi.org/10.1089/ham.2021.0073