Associations of Pulmonary Function with MRI Brain Volumes: A Coordinated Multi-Study Analysis

Impaired lung function is associated with elevated blood biomarkers of AD/ADRD: Unraveling the interplay with risk of dementia

Rationale

We hypothesize that impaired lung function contributes to dementia risk via biological mechanisms reflected in AD/ADRD-related protein biomarkers, and aim to evaluate their role in mediating this relationship.

Methods

Serum p-Tau181 and plasma Aβ42/40 ratio, NfL, and GFAP were measured in 4,072 participants (mean age 66 ± 10; 59% women) in the 2016 Health and Retirement Study. Peak Expiratory Flow (PEF) was assessed in 2012/2014, and cognitive function was measured biennially from 2014-2020 to determine dementia status. Impaired lung function (ILF) was defined as PEF <80% predicted. Multivariable regression examined associations between lung function and AD biomarkers; causal mediation analysis evaluated their role in linking lung function to incident dementia.

Results

In total, 881 (21.6%) participants had ILF and 272 (6.8%) participants developed dementia. After adjusting for demographics, education, BMI, smoking, comorbidities, inflammation, eGFR and APOE e4 , ILF was associated with a higher risk of dementia (HR=1.74; 95% CI (1.34, 225)). Individuals with ILF had 0.10 SD higher NfL (SE= 0.03; p= 0.004) and 0.09 SD higher p-Tau 181 (SE= 0.03; p= 0.002) compared to those without ILF. NfL mediated 7.3% (p=0.01) of the total effect of ILF on dementia, while p-Tau 181 mediated 5% (p=0.05) of this association.

Conclusions

ILF was associated with elevated levels of neurodegeneration markers NfL and p-Tau 181, which partially mediated its relationship with dementia risk. These findings highlight the importance of monitoring blood protein biomarkers in individuals with impaired lung health to facilitate early interventions.

Associations between cerebral small vessel disease and reduced forced vital capacity and expiratory volume in a general healthy Swedish elder population study-Good Aging in Skåne

BackgroundCerebral small vessel disease (CSVD) is one of the most important causes of cognitive decline. Only a few previous studies have evaluated lung function measures in relation to brain neuropathological changes, and even less studies on specific lesions and areas that could shed light on mechanisms of CSVD.ObjectiveThe aim was to study the association between lung function and CSVD in the general elder population.Methods379 participants, aged 72-87 years from the general population study 'Good Aging in Skåne study (GÅS)'were investigated with a 3 T MRI brain examination and spirometry. Z-scores of FEV1 and FVC were calculated using the GLI 2012 equations. Age-adjusted associations between white matter hyperintensities (WMH), medial temporal lobe atrophy (MTA), lacunar infarction, cerebral atrophies and cerebral microbleeds and lung function were calculated and stratified for sex.ResultsDecreased FEV1 and FVC z-scores below ≤ -1.0 were both associated with increased risk of WMI and global cortical atrophy. Decreased FVC z-scores were also associated with MTA and lacunar infarction in women and precuneus atrophy in men. The associations for WMH, MTA and lacunar infarctions and higher STRIVE score were noted among women, but not among men. FEV1 z scores were not related to diabetes, coronary artery disease or stroke.ConclusionsLower lung function was associated to MRI markers of CSVD in this general healthy population, particularly with WMH, especially for women. Although possible shared risk factors exist between lung and heart disease, lung function should be recognized in future studies on CSVD.

Clinical and Imaging Markers of Cardiac Function and Brain Health: A Meta-Analysis of Community-Based Studies

BACKGROUND AND OBJECTIVES

Cardiac dysfunction and heart failure are linked to cognitive impairment, but the underlying brain pathology remains undetermined. We investigated associations between cardiac function (measured by echocardiography or cardiac MRI), clinical heart failure, and structural markers on brain MRI, including volumes of gray and white matter (WM), the hippocampus, and white matter hyperintensities (WMHs).

METHODS

We leverage data from 7 prospective, community-based cohorts across Europe and the United States, all part of the Cross-Cohort Collaboration. The included cohorts were the Age, Gene/Environment Susceptibility-Reykjavik Study, Atherosclerosis Risk in Communities study, Austrian Stroke Prevention Study, Cardiovascular Health Study, Framingham Heart Study, Rotterdam Study, and Study of Health in Pomerania (SHIP-START and SHIP-TREND). Each cohort performed cross-sectional multivariable linear regression analyses, after which estimates were pooled through random-effects meta-analysis. Heterogeneity was assessed by the I2 index (%).

RESULTS

Among 10,889 participants (mean age: 66.8 years, range 52.0-76.0; 56.7% women), markers of systolic dysfunction were consistently associated with smaller total brain volume (TBV) (e.g., adjusted standardized mean difference for moderate to severe dysfunction -0.19, 95% CI -0.31 to -0.07, I2 = 20%). Impaired relaxation and restrictive diastolic dysfunction were also associated with smaller TBV (e.g., for impaired relaxation -0.08, 95% CI -0.15 to -0.01, I2 = 32%) and hippocampal volume (-0.18, 95% CI -0.33 to -0.03, I2 = 0%), with similar results for the E/A-ratio. Systolic and diastolic dysfunction was not consistently associated with volume of WMHs. Among 5 cohorts with available data, 302 (3.4%) participants had clinical heart failure, which was associated with smaller brain volumes, particularly in the hippocampus (-0.13, 95% CI -0.23 to -0.02, I2 = 1%).

DISCUSSION

In this large study among community-dwelling adults, subclinical cardiac dysfunction was associated with brain imaging markers of neurodegeneration. These findings encourage longitudinal investigations on the effect of maintaining cardiac function on brain health.

Antiageing strategy for neurodegenerative diseases: from mechanisms to clinical advances

In the context of global ageing, the prevalence of neurodegenerative diseases and dementia, such as Alzheimer's disease (AD), is increasing. However, the current symptomatic and disease-modifying therapies have achieved limited benefits for neurodegenerative diseases in clinical settings. Halting the progress of neurodegeneration and cognitive decline or even improving impaired cognition and function are the clinically meaningful goals of treatments for neurodegenerative diseases. Ageing is the primary risk factor for neurodegenerative diseases and their associated comorbidities, such as vascular pathologies, in elderly individuals. Thus, we aim to elucidate the role of ageing in neurodegenerative diseases from the perspective of a complex system, in which the brain is the core and peripheral organs and tissues form a holistic network to support brain functions. During ageing, the progressive deterioration of the structure and function of the entire body hampers its active and adaptive responses to various stimuli, thereby rendering individuals more vulnerable to neurodegenerative diseases. Consequently, we propose that the prevention and treatment of neurodegenerative diseases should be grounded in holistic antiageing and rejuvenation means complemented by interventions targeting disease-specific pathogenic events. This integrated approach is a promising strategy to effectively prevent, pause or slow down the progression of neurodegenerative diseases.

Machine learning to discover factors predicting volume of white matter hyperintensities: Insights from the UK Biobank

INTRODUCTION

Brain white matter hyperintensities (WMHs) reflect the risks of stroke, dementia, and overall mortality.

METHODS

We used a hypothesis-free gradient boosting decision tree (GBDT) approach and conventional statistical methods to discover risk factors associated with volume of WMHs. The GBDT models considered data on 2891 input features, collected ∼10 years prior to volume of WMH measurements from 44,053 participants. Top 3% of features, ranked by Shapley values, were taken forward to epidemiological analyses using linear regression.

RESULTS

Adiposity, lung function, and indicators of metabolic health (eg, glycated hemoglobin, hypertension, alkaline phosphatase, microalbumin, and urate) contribute to WMH prediction. Of lifestyle factors, smoking had the strongest association. Time spent outdoors, creatinine, and several red blood cell indices were among the identified less-known predictors of WMHs.

CONCLUSIONS

Obesity, high blood pressure, lung function, metabolic abnormalities, and lifestyle are key contributors to WMHs, providing opportunities to prevent or reduce their development.

Highlights

Obesity and related metabolic abnormalities were linked with WMHs.Associations with time spent outdoors, creatinine, some red blood cell indices and height were among the less-known risk factors identified.Action on blood pressure, metabolic abnormalities, and adequate oxygenation may help to prevent WMHs.Biomarker links may suggest simple blood tests could aid in early dementia prediction.

Systemic determinants of brain health in ageing

Preservation of brain health is a worldwide priority. The traditional view is that the major threats to the ageing brain lie within the brain itself. Consequently, therapeutic approaches have focused on protecting the brain from these presumably intrinsic pathogenic processes. However, an increasing body of evidence has unveiled a previously under-recognized contribution of peripheral organs to brain dysfunction and damage. Thus, in addition to the well-known impact of diseases of the heart and endocrine glands on the brain, accumulating data suggest that dysfunction of other organs, such as gut, liver, kidney and lung, substantially affects the development and clinical manifestation of age-related brain pathologies. In this Review, a framework is provided to indicate how organ dysfunction can alter brain homeostasis and promote neurodegeneration, with a focus on dementia. We delineate the associations of subclinical dysfunction in specific organs with dementia risk and provide suggestions for public health promotion and clinical management.

Lung function in relation to brain aging and cognitive transitions in older adults: A population-based cohort study

BACKGROUND

We investigated the association of peak expiratory flow (PEF) with dementia; cognitive impairment, no dementia (CIND); and transition from CIND to dementia, and possible underlying neuropathological mechanisms.

METHODS

A population-based cohort of adults aged 60+ was followed over 15 years to detect dementia (Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria), CIND (assessed through a cognitive battery), and progression from CIND to dementia, in relation to baseline PEF observations. A subsample (n = 462) had 6-year follow-up data on brain magnetic resonance imaging markers of neurodegeneration and small vessel disease.

RESULTS

In fully adjusted models, poor PEF performance (< 10th vs. ≥ 80th percentile) was associated with increased hazards for dementia (hazard ratio [HR] = 1.89; 95% confidence interval [CI] = 1.23-2.92) and CIND (HR = 1.55; 95% CI = 1.01-2.38) and CIND progression to dementia, although not statistically significantly (HR = 2.44; 95% CI = 0.78-6.88). People with poor PEF also experienced the fastest ventricular enlargement (β coefficient = 0.67 mL/year; 95% CI = 0.13-1.21) and had the highest likelihood of developing lacunes (odds ratio = 5.05; 95% CI = 1.01-25.23).

DISCUSSION

Poor lung function contributes to cognitive deterioration possibly through accelerated brain atrophy and microvascular damage.

HIGHLIGHTS

Poor lung function increased the risk of dementia and mild cognitive impairment (MCI). Poor lung function accelerated the progression from MCI to dementia. Poor lung function was linked to brain microvascular damage and global brain atrophy.

Association between physical activity, peak expiratory flow, and cognitive function in aging: a cross-sectional analysis

BACKGROUND

The aging global population is experiencing escalating challenges related to cognitive deficits and dementia. This study explored the interplay between pulmonary function, physical activity, and cognitive function in older U.S. adults to identify modifiable risk factors for cognitive decline.

METHODS

Utilizing NHANES 2011-2012 data, we conducted a cross-sectional analysis of 729 participants aged ≥ 60 years. Cognitive function, peak expiratory flow (PEF), and physical activity were assessed. Weighted logistic regression and mediation analyses were employed to examine associations.

RESULTS

The sample size was 729 (weighted mean [SD] age, 67.1 [5.3] years; 53.6% female participants). Preliminary correlation analysis indicated a positive correlation between the global cognitive score and physical activity (β = 0.16; p < 0.001), recreational activity (β = 0.22; p < 0.001), and PEF in percent predicted (PEF%) (β = 0.18; p < 0.001). Compared to those with a PEF% >100%, the PEF% (80-100%) group (OR, 2.66; 95% CI, 1.34-5.29; p = 0.005) and PEF% <80% group (OR, 3.36; 95% CI, 1.67-6.76; p = 0.001) were significantly associated with higher cognitive deficits risk. Recreational activity meeting guidelines was linked to a lower risk of cognitive deficits (OR, 0.24; 95% CI, 0.10-0.57; p = 0.001). Mediation analysis demonstrated that PEF mediates the relationship between physical activity and cognitive function.

CONCLUSION

This study revealed significant associations between lower PEF, diminished physical activity, and increased cognitive deficits in elderly individuals. The results supported the hypothesis that pulmonary function may mediate the connection between activity and cognitive health, emphasizing the importance of respiratory health in cognitive aging. Recognizing these associations is crucial for clinical care and public health policy aiming to mitigate cognitive decline in aging populations. While these findings are intriguing, validation through longitudinal design studies is deemed necessary.

Correlation between frailty and reduction in cortical thickness in patients with chronic obstructive pulmonary disease

Physical inactivity and cognitive impairment in patients with chronic obstructive pulmonary disease (COPD) can lead to frailty and poor prognoses. However, little is known regarding the association between frailty and the human brain. We hypothesized that the brain structure could change according to frailty in patients with COPD and focused on cortical thickness. Cortical thickness measured by magnetic resonance imaging and frailty scores using the Kihon Checklist (KCL) were assessed in 40 patients with stable COPD and 20 healthy controls. Among the 34 regions assessed, multiple regions were thinner in patients with COPD than in healthy individuals (p < 0.05). We found significant negative correlations between the eight regions and the KCL scores only in patients with COPD. After adjusting for age and cognitive impairment, the association between the left and six right regions remained statistically significant. The correlation coefficient was the strongest in the bilateral superior frontal gyrus (left: ρ = - 0.5319, p = 0.0006) (right: ρ = - 0.5361, p = 0.0005). Interestingly, among the KCL scores, the daily activity domain showed the strongest correlation (sensitivity, 90%; specificity, 73%) with the bottom quartile of the reduction in the superior frontal gyrus. Frailty in patients with COPD is associated with a thickness reduction in the cortical regions, reflecting social vulnerability.

Respiratory Dysfunction in Alzheimer's Disease-Consequence or Underlying Cause? Applying Animal Models to the Study of Respiratory Malfunctions

Alzheimer's disease (AD) is a neurodegenerative brain disease that is the most common cause of dementia among the elderly. In addition to dementia, which is the loss of cognitive function, including thinking, remembering, and reasoning, and behavioral abilities, AD patients also experience respiratory disturbances. The most common respiratory problems observed in AD patients are pneumonia, shortness of breath, respiratory muscle weakness, and obstructive sleep apnea (OSA). The latter is considered an outcome of Alzheimer's disease and is suggested to be a causative factor. While this narrative review addresses the bidirectional relationship between obstructive sleep apnea and Alzheimer's disease and reports on existing studies describing the most common respiratory disorders found in patients with Alzheimer's disease, its main purpose is to review all currently available studies using animal models of Alzheimer's disease to study respiratory impairments. These studies on animal models of AD are few in number but are crucial for establishing mechanisms, causation, implementing potential therapies for respiratory disorders, and ultimately applying these findings to clinical practice. This review summarizes what is already known in the context of research on respiratory disorders in animal models, while pointing out directions for future research.

Lung Function and Brain MRI Outcomes in the Atherosclerosis Risk in Communities Neurocognitive Study

Background

Brain imaging studies may provide etiologic insight into observed links between lung function and dementia and stroke.

Objective

We evaluated associations of lung function measures with brain MRI markers of vascular and neurodegenerative disease in the ARIC Neurocognitive Study, as few studies have examined the associations.

Methods

Lung function was measured at participants' midlife in 1990-1992 (mean age = 56±5 years) and later-life in 2011-2013 (mean age = 76±5 years), and brain MRI was performed in 2011-2013. Linear regression models were used to examine the associations of lung function with brain and white matter hyperintensity (WMH) volumes, and logistic regression models were used for cerebral infarcts and microbleeds, adjusting for potential confounders.

Results

In cross-sectional analysis (i.e., examining later-life lung function and MRI markers, n = 1,223), higher forced-expiratory volume in one second (FEV1) and forced vital capacity (FVC) were associated with larger brain and lower WMH volumes [e.g., 8.62 (95% CI:2.54-14.71) cm3 greater total brain volume per one-liter higher FEV1]. No association was seen with microbleeds in the overall sample, but higher FVC was associated with lower odds of microbleeds in never-smokers and higher odds in ever-smokers. In the cross-temporal analysis (i.e., associations with midlife lung function, n = 1,787), higher FVC levels were significantly associated with lower later-life brain volumes.

Conclusions

Our results support modest associations of better lung function with less neurodegenerative and cerebrovascular pathology, although findings for microbleeds were unexpected in ever-smokers.

Associations of Allostatic Load with Level of and Change in Cognitive Function Among Middle-Aged and Older Hispanic/Latino Adults: The Study of Latinos-Investigation of Neurocognitive Aging (SOL-INCA)

Background

Higher allostatic load (AL), a multi-system measure of physiological dysregulation considered a proxy for chronic stress exposure, is associated with poorer global cognition (GC) in older non-Hispanic white adults. However, evidence of these associations in middle-aged and older US-based Hispanic/Latino adults is limited.

Objective

To examine associations of AL with level of cognition, performance in cognition 7 years later, and change in cognition over 7 years among middle-aged and older US-based Hispanic/Latino adults.

Methods

We used data (n = 5,799, 45-74 years at baseline) from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) and SOL-Investigation of Neurocognitive Aging (SOL-INCA). The AL score comprised 16 biomarkers representing cardiometabolic, glucose, cardiopulmonary, parasympathetic, and inflammatory systems (higher scores = greater dysregulation). Cognitive outcomes included GC and individual tests of verbal learning and memory, world fluency (WF), Digit Symbol Substitution (DSS), and Trail Making (Parts A & B). Survey-linear regressions assessed associations of AL with performance in cognition at baseline, 7 years later, and via 7-year cognitive change scores adjusting for sociodemographic characteristics, lifestyle factors, and depressive symptoms.

Results

Higher AL was associated with lower baseline performance in GC and WF; and lower 7-year follow-up performance in these same measures plus DSS and Trail Making Parts A & B. Higher AL was associated with more pronounced 7-year change (reduction) in GC and on WF and DSS tests.

Conclusions

Findings extend previous evidence in predominantly older non-Hispanic white cohorts to show that AL is related to level of and change in GC (as well as WF and DSS) among middle-aged and older US-based Hispanic/Latino adults.

Impaired lung function in multiple sclerosis: a single-center observational study in 371 persons

INTRODUCTION

Abnormal lung function in people with multiple sclerosis (PwMS) could be considered as the result of muscle weakness or MS-specific structural central nervous system (CNS) abnormalities as a precipitant factor for the worsening of motor impairment or cognitive symptoms.

METHODS

This is a cross-sectional observational study in PwMS. Forced spirometry was conducted, and normative metrics of forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and the relation FEV1/FVC were calculated. Qualitative and quantitative brain magnetic resonance imaging (MRI) examinations were carried out.

RESULTS

A total of 371 PwMS were included in the study. Of those, 196 (53%) had RRMS, 92 (25%) SPMS, and 83 (22%) PPMS. Low FVC and FEV1 was present in 16 (8%), 16 (19%), and 23 (25%) of the patients in the RRMS, PPMS, and SPMS, respectively. PwMS with T2-FLAIR lesions involving the corpus callosum (CC) had a significantly higher frequency of abnormally low FVC and FEV1 (OR 3.62; 95% CI 1.33-9.83; p = 0.012) than patients without lesions in that region. This association remained significant in the RRMS group (OR 10.1; 95% CI 1.3-67.8; p 0.031) when the model excluded PPMS and SPMS. According to our study, for every increase of 1 z score of FVC, we observed an increase of 0.25 cm3 of hippocampal volume (β 0.25; 95% CI 0.03-0.47; p 0.023) and 0.43 cm3 of left hippocampus volume (β 0.43; 95% CI 0.16-0.71; p 0.002).

CONCLUSIONS

We observed an incremental prevalence of abnormally low pulmonary function tests that parallels a sequence from more early relapsing courses to long-standing progressive courses (RRMS to PPMS or SPMS).

Reduced lung function and cause-specific mortality: A population-based study of Norwegian men followed for 26 years

BACKGROUND AND AIM

Reduced lung function is associated with increased mortality, but it is unclear how different spirometric patterns are related to specific deaths. Aim of this study was to investigate these associations in a large general population cohort.

METHODS

The study population consisted of 26,091 men aged 30-46 years from the Pneumoconiosis Survey of Western Norway conducted in 1988-1990 with follow-up on date and cause of death for 26 years. Cox proportional hazard models were used to estimate the association between baseline FEV1, FVC, obstructive (OSP) and restrictive spirometric pattern (RSP) (z-scores calculated according to GLI-2012 equations) and mortality (European 2012 shortlist classification (E-2012)), after adjustment for age, body mass index, smoking habits, and education.

RESULTS

In total, 2462 (9%) subjects died. A predominant reduction of FEV1 (and OSP) were associated with respiratory non-cancer (E-8) (HR for one unit FEV1 z-score decrease 2.29 (95% CI 1.90, 2.77) and lung cancer mortality (E-2.1.8) (1.27(1.12, 1.44)). A similar reduction of FEV1 and FVC (and RSP) were associated with diabetes (E-4.1) (FEV1 2.21(1.67, 2.92), FVC 2.41(1.75, 3.32)), cerebrovascular (E-7.3) (1.52(1.21, 1.91), 1.54(1.19, 1.98)), ischemic heart disease (E-7.1) (1.22(1.10, 1.35), 1.21(1.08, 1.36)), neurological (E-6.3) (1.56(1.21, 2.01), 1.61(1.22, 2.13)), suicide (E-17.2) (1.37(1.13, 1.65), 1.29(1.04, 1.59)) and hematological cancer mortality (E-2.1.19-21) (1.29(1.05, 1.58), (1.26(1.00, 1.58)). No association was found between reduced lung function and mortality due to accidents, alcohol abuse, digestive and genitourinary cancer.

CONCLUSIONS

Spirometric obstruction was mainly related to pulmonary mortality. Spirometric restriction was mainly related to extra-pulmonary mortality.