Tau Pathologies Mediate the Association of Cigarette Smoking with Cognitive Impairment in Older Adults Without Dementia: The CABLE Study

The association of sun-cured tobacco and cigarette use with global cognitive function, verbal fluency and memory in patients with chronic obstructive pulmonary disease: A cross-sectional study

INTRODUCTION

Some elderly people in China prefer sun-cured tobacco to cigarettes, and the composition of sun-cured tobacco and cigarettes is inconsistent. The influence of cigarettes on the cognitive function of COPD patients has been widely reported, but the research on sun-cured tobacco is relatively rare. Our study explored the association of sun-cured tobacco and cigarette use with cognitive decline in COPD patients.

METHODS

This was a cross-sectional study. A total of 401 COPD patients were included, and 190, 103, and 108 participants were included in non-smoking, cigarette-smoking, and sun-cured tobacco groups, respectively. We evaluated the global cognitive function using the Beijing version of the Montreal Cognitive Assessment, verbal fluency function using an animal fluency test, and memory function using ten unrelated words.

RESULTS

The participants of both cigarette-smoking (AOR=11.18; 95% CI: 1.28- 97.5) and sun-cured tobacco (AOR=10.46; 95% CI: 1.14-96.4) groups were more likely to develop mild cognitive impairment compared to the non-smoking group. The mean z scores of global cognitive function, verbal fluency, and memory were lower in cigarette-smoking and sun-cured tobacco groups than those in a non-smoking group; Multivariable linear regression showed that global cognitive function (β= -0.61; 95% CI: -1.04 - -0.18; and β= -0.48; 95% CI: -0.91 - -0.05) and verbal fluency (β= -0.79; 95% CI: -1.33 - -0.26; and β= -0.69; 95% CI: -1.23 - -0.16) of the sun-cured tobacco group and the cigarette-smoking group were significantly lower than those of the non-smoking group when adjusting for demographic and disease-related characteristics. However, there was no significant difference between the cigarette-smoking and sun-cured tobacco groups in global cognitive function, verbal fluency, and memory.

CONCLUSIONS

Compared with non-smokers, the use of cigarettes and sun-cured tobacco may damage the cognitive function of COPD patients, especially in global cognitive function and verbal fluency.

Frailty and its combined effects with lifestyle factors on cognitive function: a cross-sectional study

BACKGROUND

Frailty describes an age-related state of deterioration in biological function. This study aimed to investigate the association between frailty and cognitive function and its combined effects with lifestyles.

METHODS

A total of 3,279 participants from the Dongfeng-Tongji (DFTJ) cohort were tested the cognitive function by using the Chinese version of Mini-mental State Examination (MMSE). Frailty was evaluated based on a 35-item frailty index (FI). Frailty status was dichotomized into robust (FI < 0.15) and frail (FI ≥ 0.15). Multivariate generalized linear regression models and logistic regression models were used to estimate the associations of frailty with MMSE score and cognitive impairment. We also analysed the modification and combined effects of lifestyle factors, including smoking status, drinking status, and regular physical exercise, on the above associations.

RESULTS

FI was significantly associated with lower MMSE score [β (95%Cl) = -0.28 (-0.43, -0.13)] and cognitive impairment [OR (95%Cl) = 1.19 (1.04, 1.35)]. The association of frailty status with MMSE were found to be stronger among ever smokers [β(95%Cl) = -1.08 (-1.64, -0.51)] and physical inactive individuals [β(95%Cl) = -1.59 (-2.63, -0.54)] while weaker or not significant among never smokers [β(95%Cl) = -0.30 (-0.62, 0.01)] and physical active individuals [β(95%Cl) = -0.37 (-0.65, -0.08))]. There were significant combined effects of frailty status with unhealthy lifestyles including smoking, alcohol drinking, and physical inactive on cognitive impairment.

CONCLUSIONS

Frailty was associated with cognitive impairment among Chinese middle-aged and elderly people, while smoking cessation and regular physical exercise could attenuate the above associations, which highlight the potential preventive interventions.

Association between air pollution and CSF sTREM2 in cognitively normal older adults: The CABLE study

Objectives

Ambient air pollution aggravates the process of Alzheimer's disease (AD) pathology. Currently, the exact inflammatory mechanisms underlying these links from clinical research remain largely unclear.

Methods

This study included 1,131 cognitively intact individuals from the Chinese Alzheimer's Biomarker and LifestylE database with data provided on cerebrospinal fluid (CSF) AD biomarkers (amyloid beta‐peptide 42 [Aβ42], total tau [t‐tau], and phosphorylated tau [p‐tau]), neuroinflammatory (CSF sTREM2), and systemic inflammatory markers (high sensitivity C‐reactive protein and peripheral immune cells). The 2‐year averaged levels of ambient fine particulate matter with diameter <2.5 μm (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) were estimated at each participant's residence. Multiple‐adjusted models were approached to detect associations of air pollution with inflammatory markers and AD‐related proteins.

Results

Ambient 2‐year averaged exposure of PM_2.5 was associated with changes of neuroinflammatory markers, that is, CSF sTREM2 (β = −0.116, p = 0.0002). Similar results were found for O₃ exposure among the elderly (β = −0.111, p = 0.0280) or urban population (β = −0.090, p = 0.0144). No significant evidence supported NO₂ related to CSF sTREM2. For potentially causal associations with accumulated AD pathologies, the total effects of PM_2.5 on CSF amyloid‐related protein (CSF Aβ42 and p‐tau/Aβ42) were partly mediated by CSF sTREM2, with proportions of 14.22% and 47.15%, respectively. Additional analyses found inverse associations between peripheral inflammatory markers with PM_2.5 and NO₂, but a positive correlation with O₃.

Interpretation

These findings demonstrated a strong link between PM_2.5 exposure and microglial dysfunction. Furthermore, CSF sTREM2 as a key mediator modulated the influences of PM_2.5 exposure on AD amyloid pathologies.