| Objective: To study the relationship between chronic periodontitis and cognitive dysfunction in Tibetan middle-aged and elderly people in hypoxic environment,and to explore the potential mechanism of periodontitis involved in MCI and AD morbidity in Tibetan middle-aged and elderly people.Methods: From October 2016 to December 2018,middle-aged and elderly Tibetans(aged over 50 years)in community of Huangnan Tibetan Autonomous Prefecture of Qinghai Province(3,287 m above sea level)were selected as the research objects.General information survey(age,sex,educational level,occupation,sports,daily living ability,emotion and place of residence,etc.)was conducted.MMSE and Mo CA cognitive scale were screened and periodontal pocket depth,clinical attachment level,bleeding index,number of missing teeth and other clinical indicators of periodontal disease were examined.78 patients with cognitive impairment were selected as case group by case-control method.In case group,22 patients with mild cognitive impairment,13 patients with dementia,26 patients with mild cognitive impairment combined with periodontitis,17 patients with dementia combined with periodontitis were selected.At the same time,82 persons with matching age,sex and educational level were selected as the control group,34 healthy persons and 48 periodontitis patients in the control group.Detection of Porphyromonas gingivalis in subgingival plaque by SYBR Green ??CT.The PPAR gamma gene Pro12 Ala locus was amplified by polymerase chain reaction and the samples were sent to the company for sequencing.Results: 1.There was no significant difference in age,sex and educational level among the six groups(P > 0.05);2.There were significant differences in the scores of Mo CA,MMSE and ADAS-Cog scales among the six groups(P < 0.01).Mo CA and MMSE scores in Chronic periodontitis(CP)group were significantly lower than those in Normal control(NC)group(P < 0.05),and ADAS-Cog scores in Chronic periodontitis(CP)group were significantly higher than those in Normal control(NC)group(P < 0.05).Mo CA and MMSE scores in MCI + CP group were significantly lower than those in Mild Cognitive Impairment(MCI)group(P < 0.05),and ADAS-Cog scores in MCI + CP group were significantly higher than those in MCI group(P < 0.05).Mo CA and MMSE scores in AD + CP group were significantly lower than those in Alzheimer's disease(AD)group(P < 0.05),and ADAS-Cog scores in AD + CP group were significantly higher than those in AD group(P < 0.05).There were significant differences in CDT,NPI and HAMA between the six groups(P < 0.001),HRSD and HIS were not(P > 0.05).3.Compared with NC group,the factors of Mo CA decreased significantly in delayed memory,executive function,working memory and language function in CP group(P < 0.05),Compared with MCI group,MCI+ CP language function score was significantly lower(P < 0.05).Compared with AD group,AD + CP group had significant differences in orientation and working memory(P < 0.05);compared with NC group,MCI group had significant differences in all factors except visual spatial ability(P < 0.05);AD group had significant differences in all factors of Mo CA(P < 0.05);compared with CP group,MCI + CP had significant differences in orientation,delayed memory and working memory(P < 0.05),AD + CP had significant differences in the levels of all factors of Mo CA(P < 0.05);4.There were significant differences among the factors of MMSE scale in the six groups(P < 0.05).Compared with NC group,delayed memory and language function of CP group were significantly decreased(P < 0.05);compared with MCI group,language function of MCI + CP group was significantly decreased(P < 0.05);compared with AD group,there were significant differences in orientation,short-term memory,delayed memory and language function of AD + CP group(P < 0.05).5.The periodontal pocket depth,attachment loss and hemorrhage index were significantly higher in MCI,AD and periodontal disease groups than those in periodontal disease group(P < 0.05).6.In 160 subjects,the total detection rate of Pg was 73.75%,44.12% in NC group,68.18% in MCI group,84.62% in AD group,79.17% in CP group,88.46% in CP+MCI group,94.12% in CP+AD group,and the difference was significant(P<0.05).7.Among 160 subjects,117 were Pro,42 were Pro/Ala,1 was Ala,and the allele frequency of Ala was 0.1375,?2=1.75.The?2 threshold table P > 0.05,so the sample is in Hardy-Weinberg equilibrium.Because of the small sample size and the low frequency of Ala carriers in some groups,MCI+CP and AD+CP were combined for statistical analysis in order to reduce errors.The genotype frequencies of Ala carriers were different among groups,and the difference was statistically significant(P < 0.05).Compared with NC group,the frequency of Ala carriers in MCI+AD group was significantly higher(P<0.00417).There was no significant difference between CP group and NC group(P>0.01250).The frequency of Ala carriers in MCI+CP&AD+CP group was significantly higher than that in MCI+AD group(P<0.00500).The frequency of Ala carriers in MCI+CP&AD+CP group was significantly higher than that in CP group(P<0.00313).8.By PPAR-Pro 12 a polymorphism,the frequency of Ala carriers in MCI+CP group was significantly higher than that in CP group(P<0.00313).The results showed that there was no significant correlation between PPAR-gamma Pro12 Ala polymorphism and MMSE and Mo CA scores in NC group(P > 0.05).In MCI+AD and CP group,there was a moderate negative correlation between Ala carriers and MMSE,and a weak negative correlation between Ala carriers and Mo CA.In MCI+CP&AD+CP group,there was a strong negative correlation between Ala carriers and MMSE,and a moderate negative correlation between Ala carriers and Mo CA.Conclusions: 1.In the high altitude hypoxia environment(Huangnan Tibetan Autonomous Prefecture of Qinghai Province),periodontitis and cognitive function of Tibetan middle-aged and elderly people are positively correlated,that is,the cognitive function of Tibetan middle-aged and elderly people with chronic periodontitis is significantly reduced,combined with periodontitis MCI and AD showed more cognitive decline in more areas;at the same time,cognitive dysfunction aggravated periodontitis,showing a high detection rate of subgingival plaque Pg and loss of gingival adhesion.2.PPAR? gene Pro/Ala polymorphism is associated with cognitive dysfunction and periodontitis,and is most strongly associated with both diseases;Ala allele carriers have a higher risk of cognitive impairment than Pro/Pro genotypes.The PPAR? gene Pro/Ala polymorphism may be a potential mechanism for the involvement of periodontitis in the pathogenesis of MCI and AD in Tibetan middle-aged and elderly people. |
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