Effects of serum homocysteine, depression and instrumental daily living ability on cognitive function in elderly people at high altitudes

Abstract Background To explore the level Homocysteine (Hcy), depressive state and daily living ability on the decline of cognition ability in elderly under hypoxic environment. Method Between June 2017 and June 2019, 288 participants of elderly (mean aged 67.13 years) Han subjects living in Xining City (altitude 2,260 meters) of Qinghai Province were divided into three groups: 125 Mild cognitive impairment (MCI), 20 Alzheimer’s disease (AD), 83 control. Serum HCY level was determined by BECKMAN COULTER biochemical analyzer. The cognition ability were used by Mini‐mental State Examination (MMSE), Geriatric Depression Scale (GDS), Auditory Verbal Learning Test (AVLT),Digit Span Test)DST),Activities Daily Living (BADL), Instrumental Activities of Daily Living (IADL). Fund project: National Key R&D Program of China (No : 2018YFC1315201). Result 1. There was no significant difference in age, gender, educational level among the three groups. 2. Compared with controland MCI groups, Hcy of AD group was significantly increased (p<0.05). GDS and IADL scores of AD group was significantly higher than MCI and control groups (p<0.05,p<0.01). 3. Compared with control group, BADL score of AD group was significantly increased (p<0.01), while there was no significant difference the BADL score between control and MCI group (p> 0.05). 4. The scores of DST, AVLT and MMSE in the forward and reverse direction, delayed memory, attention, calculation and working memory and visuospatial ability of HHcy group were significantly lower than those of normal Hcy group (p<0.01, p<0.05, p<0.05). 5. MMSE score was negatively correlated with Hcy, IADL and GDS (r=‐0.324, ‐0.228,‐0.191;p<0.01,p<0.05). Logistic analysis showed that HCY was the risk factor of cognitive dysfunction (OR=1.005, 95% CI: 1.005‐1.109, p<0.05). Conclusion The decline of cognition ability in the elderly at high altitude is correlated with Hcy, IADL and GDS. HHcy is the major risk factor for cognitive dysfunction. Combined MMSE, GDS and IADL scale scores provide objective basis for the warning, prevention and control of early cognitive dysfunction in the elderly under hypoxic environment.