A Cohort Study Of The Association Between Cognitive Decline And Daily Living Activities In The Chinese Elderly

Background The world’s population is aging rapidly,and the health of the elderly population is of great concern.As a common health problem,the impairment of activities of daily living（ADLs）in the elderly has become a hot topic in the study of cognitive impairment in the elderly.Some studies have revealed the relationship between ADLs and cognitive decline.There is a correlation between the two,but the unique link between the two is unclear.However,the accuracy of previous studies on the comprehensive evaluation of ADLs is limited,so it is necessary to explore a new classification method based on the ADLs score.Therefore,this study investigated the correlation between ADLs and cognitive decline in the elderly population through a large cohort study,and explored the specific rules of different cognitive functional domains and ADLs injury in the elderly population with cognitive dysfunction.Objective The relationship between ADLs and cognitive dysfunction was analyzed,and the damage rules of different cognitive domains and ADLs in the elderly with cognitive impairment were discussed.Methods The study subjects were selected from the Chinese Longitudinal Healthy Longevity Study（CLHLS）.Since 1998,follow-up has been conducted every 2 to 3years.The elderly who met the inclusion criteria during the 6 follow-ups from 2002 to2018 were included as the research objects.When the elderly was first enrolled in the cohort,a structured questionnaire translated and adapted from the Danish Longevity Questionnaire was used to collect baseline general demographic data.Chinese mini-Mental State Examination（MMSE）was used to assess cognitive function,and the modified Katz Scale and Lawton Scale were used to assess ADLs.A total of 39,708 elderly people were included in the CLHLS cohort,excluded age <65（n = 303）,missing data on ADLs（n = 185）,missing baseline cognitive impairment and MMSE data（n = 15817）,severe mental illness（n = 93）As well as those who were lost or died at the first follow-up（n = 11650）,there were 11660 subjects remaining in line with the purpose of this investigation.Statistics describe the distribution characteristics of general demographic data of the elderly.Latent class analysis（LCA）was used to divide ADLs into no ADL disability-no IADL disability,no ADL disability-IADL disabilty,and ADL disabilty-IADL disabilty.The COX competitive proportional hazard regression model was used to analyze the association between ADLs and cognitive dysfunction.The elderly with cognitive impairment were screened out and the cognitive functional domain scores were calculated.The Generalized liner Mixed Model（GLMM）was used to analyze the relationship between ADLs and functional domains.Results Among the 11660 elderly people included in the study,prospective observations found that 2258（19.4%）died,6521（55.9%）had cognitive impairment,and 2881（24.7%）had normal cognitive function during follow-up.Through the latent category analysis founded that 7508 cases（64.4%）were no ADL disability-no IADL disability,no ADL disability-IADL disabilty were 2990 cases（25.6%）,and ADL disabilty-IADL disabilty were 1162 cases（10.0%）.The results of the Cox competitive hazards regression models showed that after adjusting the whole model,no ADL disability-IADL disabilty（Odds Ration [OR] =1.125,95%Confidence Interval [CI]: 1.054~1.200）and ADL disabilty-IADL disabilty（OR = 1.410,95%CI: 1.280~1.550）and cognitive dysfunction the association were statistically significant（P < 0.001）.When BADL and IADL were used as independent predictors,after controlling for confounding factors,it was found that the total score of BADL（OR = 1.068,95%CI: 1.038~1.100）and the total score of IADL（OR = 1.029, 95%CI: 1.021~1.040）were significantly associated with cognitive impairment（P <0.05）.GLMM was used to analyze the correlation between functional domains and ADLs in the elderly with cognitive impairment.After adjusting for covariates,it was found that there was a statistically significant difference between no ADL disabilty-IADL disabilty and the elderly’s attention and calculation ability（OR =-0.065,95%CI:-0.107 ^-0.023）（P < 0.01）.When ADL disabilty-IADL disabilty,it is related to the Orientation（OR =-0.163,95%CI:-0.215^-0.112）,Attention and Calculation ability（OR =-0.166,95%CI:-0.231^-0.102）,Memory（OR =-0.109,95%CI:-0.203^-0.016）and Language（OR =-0.222,95%CI:-0.272^-0.017）of the elderly have statistically significant associations（P < 0.05）.There is no correlation with registration ability（P =0.151）.Conclusion Impairment of daily living activities significantly increases the risk of cognitive impairment in elderly Chinese.In the elderly with cognitive impairment,no ADL disabilty-IADL disabilty first caused the decrease of attention and calculation ability,while there was no significant difference between the occurrence of ADLs disabilty and the decrease of registration ability in the elderly.