Individual chronic mountain sickness symptom is an early warning sign of cognitive impairment

To investigate the relationship between various chronic mountain sickness (CMS) symptoms and cognitive performances and identify whether individual CMS symptom can be used as early warning signs of specific cognitive impairment in long-term high altitude migrators.

A total of 287 workers living at an altitude of 3850 m for 1-5 years participated in the study. According to the International Qinghai CMS Diagnostic Criteria, a questionnaire survey was conducted to measure the existence and severity of 7 self-perceptible CMS symptoms in addition to hemoglobin (Hb) levels in the blood. Six neurobehavioral tests were then conducted to assess cognitive function, and physiological indices, including Pittsburgh Sleep Quality Index (PSQI) and arterial oxygen saturation were also measured.

Compared with a score of 0 for each CMS symptom, scores of 1-3 universally corresponded to impairment in some aspects of cognition. Moreover, the correlation analysis revealed that subjects with different CMS symptoms exhibited specific aspects of cognitive impairment. Cyanosis was associated with slower auditory and visual reactions, reduced motion agility and poor visual memory ability (R = =0.236, 0.261, 0.155, 0.221, P < 0.01). Sleep disturbance and excessive erythrocytosis were significantly correlated to poor memory ability (R = =0.206~0.251, P < 0.01), and the symptoms of headache were mainly associated with impaired motion agility (R = =0.266, P < 0.01). The results also indicated that Hb ≥ 200 g/L, SpO₂ ≤ 88%, and PSQI scores ≥ 7, which correspond to excessive erythrocytosis, cyanosis and sleep disturbance symptoms respectively, predicted the decline of cognitive function.

The characteristics of symptoms used in Qinghai CMS Score System were associated with specific cognitive impairments in long-term plateau migrators, which supported the usefulness of monitoring cognitive status using CMS-related symptoms for both CMS patients and non-CMS people at high altitude.