THE CHANGE OF SERUM INFLAMMATORY FACTOR LEVELS IN TIBETAN AND HAN NATIONALITY PATIENTS WITH MILD COGNITIVE IMPAIRMENT AND ALZHEIMER’S DISEASE IN DIFFERENT HIGH-ALTITUDE AREAS

Abstract

Increasing evidence indicates that chronic hypoxia contributes to the decline in cognitive function. To study Tibetan and Han nationality patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) at various high altitude areas, serum inflammatory factor levels were evaluated. The participants included Hans of Dezhou, Shandong province (LA) (low altitude at 53 meter), both Hans and Tibetans of Xining, Qinghai province(MA)(middle altitude at 2,260 meter), Tibetans of Yushu, Qinghai province (HA) (high altitude at 3,800 meter above sea level). The cognitive function of AD and MCI patients was evaluated by MMSE, ADAS-Cog, and CDT. Serum IL-1β, IL-6, IL-10, TNF-α and TGF-β were measured in 30 AD patients, 35 MCI patients and 35 cognitively normal controls (NC) using indirect ELISA. Serum TNF-α, IL-1β and IL-6 of AD were significantly increased at different altitudes compared with NC groups at same altitude. Serum IL-6 and IL-1β of MCI in Tibetans were significantly higher than Tibetans NC group at HA (P < 0.05), while serum IL-10 and TGF-β of anti-inflammatory cytokines of the participants did not show change at different altitudes. Serum level of TNF-α, IL-1β and IL-6 were significantly higher in AD of Tibetans at HA than those at MA (P < 0.05, P < 0.01). Serum TNF-α of Tibetans MCI group at HA is significantly higher when compared with those at MA (P < 0.05). Serum IL-1β in MCI of Hans was significantly higher at MA than at LA. Serum levels of IL-1β was correlated with MMSE score (r=–0.194, P<0.01) in the whole sample, while a negative correlation between serum concentrations of TNF-α and ADAS-Cog scores was found in MCI patients (r=-0.745, P<0.01). The increase of TNF-α, IL-1β and IL-6 in those MCI and AD patients might be related to induction of the inflammatory suppression. Serum inflammatory factors were not significantly correlation between Hans and Tibetans patients in MCI and AD. These results imply that change of serum inflammatory factor levels of MCI and AD patients depends on altitude. The extent of hypoxia in inflammation might mediate severity of cognitive impairment.