Association of cognitive impairment and elderly mortality: differences between two cohorts ascertained 6-years apart in China

Abstract

Background: Cognitive impairment is a major contributor to mortality among the elderly. However, the relationship between cognitive impairment evaluated by educational levels and mortality and the trend between cognitive impairment and mortality with time are unclear. We aim to evaluate the differences in associations of cognitive impairment, taking the stratification by educational levels into account, with all-cause mortality and further explore the relationship of cognitive impairment with mortality in different age and sex groups in two cohorts ascertained 6 years apart in China. Methods: A total of 13,906 and 13,873 Chinese elderly aged 65 years and older were included in the 2002-2008 and 2008-2014 cohorts from the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Mortality data was ascertained from interviews with family members or relatives of participants. Cognitive function, evaluated by the Mini-Mental State Examination (MMSE), were defined by different cutoffs taking educational background into account. Cox models were used to explore the relationship of cognitive impairment with mortality.

Associations Between Anemia, Cognitive Impairment, and All-Cause Mortality in Oldest-Old Adults: A Prospective Population-Based Cohort Study

“…The Mini-Mental Status Examination (MMSE) is a sensitive, valid, and reliable instrument that is used extensively in clinical and research settings to measure cognitive impairment ( 21 ). Cognitive impairment was assessed by the Chinese version of the MMSE ( Supplementary Table 1 ) ( 22 ), of which the validity and reliability have been verified ( 13 , 23 , 24 ). Based on the MMSE score combined with the educational time, cognition impairment was defined as an MMSE score <18 in illiterate participants, <21 in those with 1–6 education years, or <25 in those with over 6 education years ( 13 , 25 ).…”

“…Data for covariates information were collected during home interviews and biochemistry tests. Based on the literature ( 13 , 24 , 26 – 28 ), we selected the following covariates: age at the baseline, sex, marital status (married and living with spouse/other), education years (0/1–6/>6), ethnicity (Han/others), smoking (yes/no), drinking (yes/no), body mass index(BMI is defined as the body mass divided by the square of the body height, and is universally expressed in units of kg/m 2 ), Chronic conditions (hypertension, diabetes mellitus, chronic kidney disease (CKD), albumin, fasting blood glucose (FBG), high sensitivity c-reactive protein (hs-CRP), and lipid profile. Hypertension patients were defined as those with systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg, or self-reporters ( 29 ).…”

“…Cognitive impairment is another condition that commonly affects older adults. This condition is burdensome and it poses a heavy burden on the public health system ( 13 ). Several studies have shown an association between cognitive impairment and increased mortality ( 13 – 15 ).…”

“…This condition is burdensome and it poses a heavy burden on the public health system ( 13 ). Several studies have shown an association between cognitive impairment and increased mortality ( 13 – 15 ). Interestingly, anemia is a known risk factor for cognitive impairment ( 12 , 16 , 17 ).…”

Inequalities in cognitive impairment among older adults in China and the associated social determinants: a decomposition approach

“…Cognitive impairment is characterized by declines in attention, memory, reasoning, intelligence and other mental functions [ 1 ]. Older adults with severe cognitive impairment can lead to dementia, which is still incurable [ 2 ]. Dementia also can make the older adults lose the ability to accomplish daily life and independent living, which has a profound adverse impact on older people’s health and successful aging, and subsequently places a heavy burden on families and healthcare systems [ 3 , 4 ].…”