Impact of smoking on cognitive decline in early old age: the Whitehall II cohort study

The association between cognitive decline and exposure to secondhand smoke at work in economically active older adults

OBJECTIVES

Secondhand smoking may contribute to cognitive decline, but evidence on this subject is limited in the working economically active older adults. This study aimed to investigate the association between cognitive decline and exposure to secondhand smoke at work in economically active adults aged 65 years or above.

STUDY DESIGN

Cross-sectional study using nationwide data.

METHODS

Data were from the 2022 Korea Community Health Survey. Chi-squared test was used to perform descriptive statistics. The association between cognitive decline and exposure to secondhand smoke at work was analysed using multivariable logistic regression analysis. Subgroup analysis was performed based on to exposure status to secondhand smoke at home and diabetes mellitus.

RESULTS

Of a total of 28,197 adults, 8767 (28.5%) individuals reported cognitive decline. Compared to individuals without exposure to passive smoking at work, those with such exposure were more likely to report cognitive decline (odds ratio: 1.30, 95% confidence interval: 1.14-1.47). This association was particularly strong in individuals with exposure to passive smoking at both work and home and in those diagnosed with diabetes mellitus.

CONCLUSIONS

Exposure to secondhand smoking at work is associated with a higher likelihood of cognitive decline in older-aged economically active individuals. The findings infer the importance of monitoring passive smoking and implementing public health measures to reduce workplace secondhand smoke exposure.

Latent profiles of modifiable dementia risk factors in later midlife: relationships with incident dementia, cognition, and neuroimaging outcomes

In 2020, the Lancet Commission identified 12 modifiable factors that increase population-level dementia risk. It is unclear if these risk factors co-occur among individuals in a clinically meaningful way. Using latent class analysis, we identified profiles of modifiable dementia risk factors in dementia-free adults aged 60-64 years from the UK Biobank. We then estimated associations between these profiles with incident dementia, cognition, and neuroimaging outcomes, and explored the differences across profiles in the effects of a polygenic risk score for Alzheimer's disease on outcomes. In 55,333 males and 63,063 females, three sex-specific latent profiles were identified: cardiometabolic risk, substance use-related risk, and low risk. The cardiometabolic risk profile in both males and females was associated with greater incidence of all-cause dementia (male: OR [95% CI] = 2.33 [2.03, 2.66]; female: OR [95% CI] = 1.44 [1.24, 1.68]), poorer cognitive performance, greater brain atrophy, and greater white matter hyperintensity volume compared to the low risk profile. The substance use-related risk profile in males was associated with poorer cognitive performance and greater white matter hyperintensities compared to the low risk profile, but no difference in all-cause dementia incidence was observed (OR [95% CI] = 1.00 [0.95, 1.06]). In females, the substance use-related risk profile demonstrated increased dementia incidence (OR [95% CI] = 1.58 [1.57, 1.58]) and greater brain atrophy but smaller white matter hyperintensity volume compared to the low risk profile. The polygenic risk score had larger effects among females, and differentially influenced outcomes across profiles; for instance, there were larger effects of the polygenic risk score on atrophy in the cardiometabolic profile vs. the low risk profile among males, and larger effects of the polygenic risk score on loss of white matter integrity in the cardiometabolic profile vs. the low risk profile among females. These results reveal three modifiable dementia risk profiles, their unique cognitive/neuroimaging outcomes, and their interactions with genetic risk for Alzheimer's disease. These differences highlight the need to consider population heterogeneity in risk prediction tools and in planning personalized prevention strategies.

State of the Science on Brain Insulin Resistance and Cognitive Decline Due to Alzheimer's Disease

Type 2 diabetes mellitus (T2DM) is common and increasing in prevalence worldwide, with devastating public health consequences. While peripheral insulin resistance is a key feature of most forms of T2DM and has been investigated for over a century, research on brain insulin resistance (BIR) has more recently been developed, including in the context of T2DM and non-diabetes states. Recent data support the presence of BIR in the aging brain, even in non-diabetes states, and found that BIR may be a feature in Alzheimer's disease (AD) and contributes to cognitive impairment. Further, therapies used to treat T2DM are now being investigated in the context of AD treatment and prevention, including insulin. In this review, we offer a definition of BIR, and present evidence for BIR in AD; we discuss the expression, function, and activation of the insulin receptor (INSR) in the brain; how BIR could develop; tools to study BIR; how BIR correlates with current AD hallmarks; and regional/cellular involvement of BIR. We close with a discussion on resilience to both BIR and AD, how current tools can be improved to better understand BIR, and future avenues for research. Overall, this review and position paper highlights BIR as a plausible therapeutic target for the prevention of cognitive decline and dementia due to AD.

Sex Differences in Alterations of Brain Functional Network in Tobacco Use Disorder

INTRODUCTION

Many studies have found sex differences in alterations of brain function in cigarette-smoking adults from the perspective of functional activity or connectivity. However, no studies have systematically found different alteration patterns in brain functional topology of cigarette-smoking men and women from three perspectives: nodal and network efficiency and modular connections.

AIMS AND METHODS

Fifty-six tobacco use disorder (TUD) participants (25 women) and 66 non-TUD participants (28 women) underwent a resting-state functional magnetic resonance imaging scan. The whole-brain functional networks were constructed, and a two-way analysis of covariance with false discovery rate correction (q < 0.05) was performed to investigate whether men and women TUD participants had different alterations in the topological features at global, modular, and nodal levels.

RESULTS

Compared to non-TUD participants, men but not women TUD participants showed significantly lower global efficiency (lower intermodular connections between the visual and executive control and between the visual and subcortical modules did not pass the correction) and significantly lower nodal global efficiency in the right superior occipital gyrus, bilateral fusiform gyrus, the right pallidum, right putamen, the bilateral paracentral lobule, the postcentral gyrus, and lower nodal local efficiency in the left paracentral lobule.

CONCLUSIONS

Men and women TUD participants have different topological properties of brain functional network, which may contribute to our understanding of neural mechanisms underlying sex differences in TUD.

IMPLICATIONS

Compared to non-TUD participants, we found men but not women TUD participants with significantly lower network metrics at global, modular, and nodal levels, which could improve our understanding of neural mechanisms underlying sex differences in TUD and lay a solid foundation for future sex-based TUD prevention and treatment.

Factors associated with self-neglect from a salutogenic perspective among community-dwelling older adults: A cross-sectional correlational study

OBJECTIVES

To identify the associated factors of self-neglect in older adults from a salutogenic perspective.

METHODS

A cross-sectional correlational study was conducted in two communities in Beijing with 486 older adults recruited from April to December 2022. Data were collected by a set of questionnaires.

RESULTS

Sense of coherence (β=-0.138), socio-demographic generalized resistance resources (GRRs) (smoking: β=0.156), social GRRs (living alone: β=0.093), psychological GRRs (self-esteem: β=-0.126), and motivational GRRs (powerful others locus of control: β=-0.199, chance locus of control: β=0.119) were all associated with self-neglect among older adults (p<0.05).

CONCLUSIONS

Sense of coherence and GRRs are vital to improve self-neglect in older adults. It is suggested to increase the level of self-esteem and the tendency of the health locus of control to largely facilitate self-neglect management in older adults.

Explaining Substance Use among Puerto Rican Older Adults: Impact of Perceived Discrimination, Perceived Stress, and Social Activities

Background: Despite Puerto Ricans having one of the highest rates of substance use among Hispanic groups in the United States, limited research has focused on the impact of perceived discrimination and stress on substance use among older adults. Individuals who experience stressful events are inclined to engage in harmful behaviors as a coping mechanism. Objectives: Based on the propositions of the General Strain Theory, the current study explores the relationship between perceived discrimination, perceived stress, social activities, and the use of alcohol and cigarettes. Methods: Baseline data from the Boston Puerto Rican Health Study collected in 2014 was used to conduct a logistic regression analysis. Results: The findings reveal that while perceived discrimination is significantly linked to both types of substance use, social activities may serve as a protective factor for cigarette use. Conclusion/Importance: Our study findings emphasize the need to examine perceived discrimination as a stressor impacting the health and well-being of Puerto Ricans in later adulthood. Policy implications for reducing substance use and directions for future research are discussed.

Is Subjective Cognitive Decline Associated with Behavioral Health Outcomes Among Mothers?

OBJECTIVES

Studies suggests that pregnancy can alter the maternal neurological function of the brain (i.e., result in cognitive decline) in a way that remains prevalent well into middle and older adulthood. However, little research has explored these changes and how they might affect behavioral health outcomes, such as substance use and depression.

METHODS

We merged data from the 2016, 2017, and 2018 Behavioral Risk Factor Surveillance System (BRFSS) surveys, with a final analytic sample of 1330 female participants (649 participants were mothers). Chi-square tests or t-tests were used to examine differences in demographic and health characteristics of the sample by subjective cognitive decline (SCD) status. To test the study hypotheses, three generalized linear mixed models were estimated with a logit link.

RESULTS

SCD was not associated with alcohol misuse among mothers (aOR = 0.27, p = 0.23). Mothers with SCD were more likely to smoke (aOR = 3.33, p = 0.01) and experience mental distress (aOR = 6.59, p < 0.001) than those without SCD.

CONCLUSION

Interventions aimed at supporting mothers should consider how existing mental health and tobacco cessation programs can be adapted to better serve this population and should aim to identify those that may have early signs of early signs of neurodegenerative conditions.

Visual memory and alcohol use in a middle-aged birth cohort

Light and moderate alcohol use has been reported to be associated with both impaired and enhanced cognition. The purpose of this study was to explore whether there was a linear relationship between visual memory and alcohol consumption in males and females in a large middle-aged birth cohort population in cross-sectional and longitudinal settings. Data were collected from 5585 participants completing 31-year (1997-1998) and 46-year (2012-2014) follow-ups including Paired Associate Learning (PAL) test at 46-years follow-up. The participants were originally from 12,231 study population of the Northern Finland Birth Cohort 1966 (NFBC1966). The PAL test was conducted to assess visual memory. Reported alcohol use was measured as total daily use of alcohol, beer, wine, and spirits converted into grams and as frequency and amount of use of beer, wine, and spirits. The total daily alcohol use was not associated with reduced visual memory. The frequency of use of beer and wine in males was associated with better visual memory in cross-sectional and longitudinal settings. Using six or more servings of spirits was associated with worse visual memory in males in cross-sectional and longitudinal settings. Using six or more servings of spirits was associated with worse visual memory in males in cross-sectional and longitudinal setting. The study suggested a lack of a linear association between drinking and visual memory in the middle-aged population.

Cardiovascular risk factors and carotid intima-media thickness with neurocognitive dysfunction in people living with HIV on stable combination anti-retroviral therapy

The goal of this clinical research was to determine the relationship between carotid intima-media thickness (cIMT), cardiovascular risk factors, and neuro-cognitive function in people living with HIV (PLHIV) and were on stable combination anti-retroviral therapy (cART). This is a cross-sectional study performed at a single center, including 149 patients who visited the anti-retroviral therapy center of our tertiary care hospital. Among the PLHIV of our research, 62.4% had at least one associated cardiovascular risk factor, and 61.1% of them had abnormally high cIMT (≥ 0.9 mm on any one side, p = 0.035). These factors and being the male gender (p = 0.028) were associated with a greater Framingham 10-year risk percentage. Hypercholesterolemia was observed in 30.9% of the PLHIV and a higher body mass index (≥ 25 kg/m2) was found in 26.8% of them. The cognitive impairment was milder in 71.8% of cases and moderate in 9.4% of PLHIV. The Chi-square test revealed that a higher proportion of participants who had lower HDL-C levels (p = 0.045), smokers (p = 0.029), systolic blood pressure ≥ 140 mmHg (p = 0.012), and lower educational status (p = 0.017) had a poorer cognitive performance. In our sample population, a higher prevalence of elevated cIMT, cardiovascular risk factors, and mild and moderate cognitive deficiency was observed in PLHIV, who were on stable cART. However, routine assessment of the neuropsychological functions and management of modifiable risk factors are not performed in our patients. Further exploration of the relationship between cardiovascular risks, cIMT, and cognitive impairment in PLHIV is essential to formulate the guidelines and delay the onset of neurocognitive disorders in these patients.

How Does Tobacco Use Affect the Cognition of Older Adults? A Propensity Score Matching Analysis Based on a Large-Scale Survey

INTRODUCTION

Tobacco is a well-established risk factor for cancer, but its association with other morbidities needs consideration. The low-income and middle-income countries (LMICs) with unprecedented demographic transformation lack evidence on tobacco use and its impact on cognitive health.

AIMS AND METHODS

Using a propensity score matching approach, we utilized data from the Longitudinal Ageing Study of India. Study employed 1:1 nearest neighbor matching with the replacement methodology. We estimated the odds of the poor cognitive score and tobacco use among older adults based on five different models for ever tobacco user, former tobacco user, current tobacco user, current smokers, and current smokeless tobacco users with reference to never tobacco users.

RESULTS

The estimated average treatment effect for the treated and the untreated group has shown a higher likelihood of cognitive decline among ever (OR -0.26; 95%CI -0.43 to -0.09), current (OR -0.28; 95%CI -0.45 to -0.10), and former (OR -0.53; 95%CI -0.87 to -0.19) tobacco users compared to never tobacco users. The finding further suggests the odds of lower cognitive scores among older adults who were smokers (OR -0.53; 95%CI -0.87 to -0.19) and smokeless tobacco users (OR -0.22; 95%CI -0.43 to -0.01) as compared to never tobacco users.

CONCLUSIONS

Interventions designed to prevent the incidence of cognitive impairment should focus on limiting the use of tobacco. Strategies under the tobacco-free generation initiative should be amplified in order to prevent future generations from productivity loss, premature ageing and to promote healthy aging.

IMPLICATIONS

Evidence of a definitive association between tobacco consumption and cognition among older adults is sporadic in LMICs. Though tobacco is a risk factor for various diseases including cancer, the extent of its impact on cognitive health among the older population is limited. This study contributes to the existing literature by highlighting poor cognitive outcomes among older adults who smoke tobacco and/or consume smokeless tobacco as compared to never-tobacco users. Our findings emphasize the need to accelerate programmes related to tobacco-free generation in LMICs to reach a higher quality of life and healthy aging in pursuit of achieving the sustainable development goal of "good health and well-being."

Role of Cognitive Frailty in Older Adults With Cardiovascular Disease

As the older adult population expands, an increasing number of patients affected by geriatric syndromes are seen by cardiovascular clinicians. One such syndrome that has been associated with poor outcomes is cognitive frailty: the simultaneous presence of cognitive impairment, without evidence of dementia, and physical frailty, which results in decreased cognitive reserve. Driven by common pathophysiologic underpinnings (eg, inflammation and neurohormonal dysregulation), cardiovascular disease, cognitive impairment, and frailty also share the following risk factors: hypertension, diabetes, obesity, sedentary behavior, and tobacco use. Cardiovascular disease has been associated with the onset and progression of cognitive frailty, which may be reversible in early stages, making it essential for clinicians to diagnose the condition in a timely manner and prescribe appropriate interventions. Additional research is required to elucidate the mechanisms underlying the development of cognitive frailty, establish preventive and therapeutic strategies to address the needs of older patients with cardiovascular disease at risk for cognitive frailty, and ultimately facilitate targeted intervention studies.

Sarcopenia using muscle mass prediction model and cognitive impairment: A longitudinal analysis from the English longitudinal study on ageing

BACKGROUND

Literature on the association between sarcopenia and cognitive impairment is largely unclear and mainly limited to non-European populations. Therefore, the aim of this study is to explore if the presence of sarcopenia at the baseline could increase the risk of cognitive impairment in a large cohort of older people participating to the English Longitudinal Study of Ageing (ELSA), over ten years of follow-up.

METHODS

Sarcopenia was diagnosed as having low handgrip strength and low skeletal muscle mass index at the baseline, using a muscle mass prediction model; cognitive function was evaluated in the ELSA through several tests. The results are reported in the whole sample adjusted for potential baseline confounders and after matching sarcopenic and non-sarcopenic participants with a propensity score.

RESULTS

2738 people (mean age: 68.7 years, 54.4% males) were included. During the ten years of follow-up, sarcopenia was associated with significantly lower scores in memory (p < 0.001), verbal fluency (p < 0.001), immediate word recall (p <0.001), delayed word recall (p = 0.018), and in recall summary score (p < 0.001). After adjusting for eight potential confounders, the presence of sarcopenia was significantly associated with poor verbal fluency (odds ratio, OR= 1.417, 95% confidence intervals, CI= 1.181-1.700) and in propensity-score matched analyses (OR=1.272, 95%CI= 1.071- 1.511).

CONCLUSIONS AND IMPLICATIONS

Sarcopenia was found to be associated with a significantly higher incidence of poor cognitive status in a large population of elderly people followed up for 10 years, suggesting it may be an important potential risk factor for dementia.

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.

Olfactory Dysfunction Associated with Cognitive Decline in an Elderly Population

BACKGROUND

In many neurological disorders, including Alzheimer disease, early olfactory dysfunction is observed.

OBJECTIVE

In order to determine if deficits in olfactory memory are present in the elderly and if olfactory dysfunction correlates with cognitive impairment in the aging population, olfactory testing has been done on seniors from the NuAge cohort accepting to participate in the Olfactory Response Cognition and Aging (ORCA) secondary sub-study. The t-Mini Mental Statement Examination and the Telephone Interview for Cognitive Status tests were done to assess cognition levels.

RESULTS

Overall, 94% of the ORCA cohort displayed olfactory dysfunction. Deficits in olfactory memory were also present. A correlation was observed between olfactory function and cognitive test scores. Moreover, in women who smoked, there was an association between olfactory memory and cognitive scores.

CONCLUSION

Our results suggest that olfactory dysfunction may predict impending cognitive decline and highlights the need for olfactory training in seniors to improve olfaction and overall well-being.

An explainable machine learning based prediction model for Alzheimer's disease in China longitudinal aging study

Alzheimer's disease (AD) is the most common cause of dementia. Accurate prediction and diagnosis of AD and its prodromal stage, i.e., mild cognitive impairment (MCI), is essential for the possible delay and early treatment for the disease. In this paper, we adopt the data from the China Longitudinal Aging Study (CLAS), which was launched in 2011, and includes a joint effort of 15 institutions all over the country. Four thousand four hundred and eleven people who are at least 60 years old participated in the project, where 3,514 people completed the baseline survey. The survey collected data including demographic information, daily lifestyle, medical history, and routine physical examination. In particular, we employ ensemble learning and feature selection methods to develop an explainable prediction model for AD and MCI. Five feature selection methods and nine machine learning classifiers are applied for comparison to find the most dominant features on AD/MCI prediction. The resulting model achieves accuracy of 89.2%, sensitivity of 87.7%, and specificity of 90.7% for MCI prediction, and accuracy of 99.2%, sensitivity of 99.7%, and specificity of 98.7% for AD prediction. We further utilize the SHapley Additive exPlanations (SHAP) algorithm to visualize the specific contribution of each feature to AD/MCI prediction at both global and individual levels. Consequently, our model not only provides the prediction outcome, but also helps to understand the relationship between lifestyle/physical disease history and cognitive function, and enables clinicians to make appropriate recommendations for the elderly. Therefore, our approach provides a new perspective for the design of a computer-aided diagnosis system for AD and MCI, and has potential high clinical application value.

EncephalApp Stroop Test for covert hepatic encephalopathy screening in Tunisian cirrhotic patients

Background: Covert hepatic encephalopathy (CHE) is underdiagnosed and is difficult to detect. The EncephalApp Stroop test is validated for its screening. The aim of the study was to define Tunisian norms for the test based on healthy controls norms and to estimate the prevalence of CHE in cirrhotic Tunisian patients. Methods: A prospective, multicenter, cross-sectional study was conducted. Ambulatory or hospitalized cirrhotic patients aged 40 years and over were recruited at 11 centers. Healthy subjects aged 40 years and over were recruited at 8 centers. We used a translated Arabic version of the streamlined EncephalApp Stroop test. The task has two components: "Off" and "On" state depending on the discordance or concordance of the stimuli. Results: 142 patients were included. The mean age was 57.26 years [40-86]. 40 (28.17%) of cirrhotic patients who were included were diagnosed as having a minimal hepatic encephalopathy or CHE. Among the ineligible patients, 22 had overt hepatic encephalopathy. If we consider these patients, the overall prevalence rate of CHE was around 24.39% in cirrhotic patients. It was more frequent in women (34.21% vs 25.96%), and in patients whose level of school education is between 6 and 13 years. Its prevalence does not appear to be affected by gender, MELD score, etiology of cirrhosis and age group of patients, as these variables were independent with respective p according to the chi-square test 0.413; 0.736; 0.663 and 0.1. The stroop times (On / Off and On + Off) correlated significantly with each other, are associated significantly and positively with age (respective Pearson coefficients: 0.578; 0.567 and 0.6). The more the age increases, the more the stroop response times increases (p > 10 -3). Conclusions: EncephalApp Stroop test was an efficient screening tool for CHE in Tunisian cirrhotic patients.

The role of lifestyle factors in cognitive health and dementia in oldest-old: A systematic review

Oldest-old is the fastest growing segment of society. A substantial number of these individuals are cognitively impaired or demented. Given the lack of a cure, attention is directed to lifestyle interventions that could help alleviate the stress in patients, their families, and society. The aim of this review was to identify lifestyle factors with important roles in dementia prevention in oldest-old. Searches were conducted in PubMed, EMBASE, Scopus and Web of Science. We identified 27 observational cohort studies that met the inclusion criteria. Results showed that eating a healthy diet with plenty of fruits and vegetables, and participation in leisure and physical activities may protect against cognitive decline and cognitive impairment among oldest-old regardless of the APOE genotype. Combined lifestyles may generate multiplicative effects than individual factors. This is the first review known to systematically examine the association between lifestyle and cognitive health in oldest-old. Lifestyle interventions for diet, leisure, or a combination of lifestyles could be beneficial for cognitive function in oldest-old. Interventional studies are warranted to strengthen the evidence.

Development of Dependence in Smokers and Rodents With Voluntary Nicotine Intake: Similarities and Differences

INTRODUCTION

Smoking and vaping throughout adolescence and early adulthood lead to nicotine dependence. Nicotine withdrawal is associated with somatic and affective withdrawal symptoms that contribute to smoking and relapse. Affective nicotine withdrawal symptoms in humans include craving for cigarettes, depression, anxiety, trouble sleeping, and cognitive deficits.

METHODS

Herein, we review clinical studies that investigated nicotine dependence in people who smoke or vape. We also discuss studies that investigated the development of dependence in animals with oral nicotine intake, nicotine aerosol self-administration, and intravenous nicotine self-administration.

RESULTS

Clinical studies report that adolescents who smoke daily develop nicotine dependence before those who smoke infrequently, but ultimately all smokers become dependent in adulthood. Preclinical studies indicate that rats that self-administer nicotine also become dependent. Rats that self-administer nicotine display somatic withdrawal signs and affective withdrawal signs, including increased anxiety and depressive-like behavior, cognitive deficits, and allodynia. Most nicotine withdrawal signs were observed in rodents with daily (7 days/week) or intermittent long access (23-hour) to nicotine. Clinical smoking studies report symptoms of nicotine dependence in adolescents of both sexes, but virtually all preclinical nicotine self-administration studies have been done with adult male rats.

CONCLUSIONS

The role of sex and age in the development of dependence in nicotine self-administration studies remains under-investigated. However, the role of sex and age in nicotine withdrawal has been thoroughly evaluated in studies in which nicotine was administered noncontingently. We discuss the need for volitional nicotine self-administration studies that explore the gradual development of dependence during adolescence and adulthood in rodents of both sexes.

IMPLICATIONS

The reviewed clinical studies investigated the development of nicotine dependence in male and female adolescent and young adult smokers and vapers. These studies indicate that most adolescent smokers and vapers gradually become nicotine dependent. Preclinical studies with rodents show that nicotine intake in widely used self-administration models also leads to dependence. However, almost all animal studies that investigated the development of nicotine dependence have been conducted with adult male rats. To better model smoking and vaping, it is important that nicotine intake in rats or mice starts during adolescence and that both sexes are included.

Cognitive Activities, Lifestyle Factors, and Risk of Cognitive Impairment, with an Analysis of the Apolipoprotein Epsilon 4 Genotype

INTRODUCTION

Cognitive stimulating activities and a healthy lifestyle are associated with less cognitive impairment. However, whether the association is varied by Apolipoprotein epsilon 4 (APOE ε4) allele carrier status remains inconclusive. We aimed to investigate whether the association of cognitively stimulating activities and a healthy lifestyle with the risk of cognitive impairment varied by APOE ε4 allele carrier status.

METHODS

A case-control study was conducted for adults aged 60 years and above. Six province administrative units (Beijing, Shanghai, Hubei, Sichuan, Guangxi, and Yunnan) were included using stratified multistage cluster sampling. A total of 1,300 individuals were identified with cognitive impairment (cases) at enrollment and were matched 1:2 on sex, age (±2 years), and residential district with controls who were cognitively normal at the time of the evaluation. We used a standardized questionnaire to collect information on cognitive stimulating activities, lifestyle factors, demographics, and comorbidity. Cognitive stimulating activities included reading books or newspapers, playing cards or mahjong, using the Internet, socializing with neighbors, and community activities. Lifestyle factors included smoking, alcohol drinking, daily tea drinking, and regular exercise. We used logistic regression to assess the interaction between cognitive stimulating activities, lifestyle factors, and APOE ε4 allele carrier status (yes/no) on the risk of cognitive impairment. We tested for additive interaction by estimating relative excess risk (RERI) due to interaction and multiplicative interaction employing the p value of the interaction term of each lifestyle factor and APOE ε4 into the model.

RESULTS

Four cognitive stimulating activities were associated with less cognitive impairment regardless of APOE ε4 status. Using the Internet (odds ratio [OR]: 0.53, 95% confidence interval [CI]: 0.30-0.95), daily tea drinking (OR: 0.79; 95% CI: 0.63-0.98), and regular exercise (OR: 0.78; 95% CI: 0.65-0.94) were associated with less cognitive impairment only in noncarriers. Multiplicative and additive interactions were found between community activities and APOE ε4 carrier status (multiplicative p value = 0.03; RERI 0.738, 95% CI: 0.201-1.275).

CONCLUSION

The associations between cognitive activities and cognitive impairment were robust regardless of the APOE ε4 carrier status, while the associations between lifestyle factors and cognitive impairment varied by APOE ε4 carrier status.

Urinary tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and cognitive functioning in older adults: The National Health and Nutrition Examination Survey 2013-2014

INTRODUCTION

Tobacco contains carcinogens called tobacco-specific nitrosamines. Among the tobacco-specific nitrosamines, is nicotine-derived nitrosamine ketone (NNK) which produces the metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). We aimed to examine the association between urinary tobacco-specific NNAL and cognitive functioning among older adults.

METHODS

A total of 1673 older adults aged ≥60 years from the National Health and Nutrition Examination Survey 2013-2014 were included. Urinary tobacco-specific NNAL was analyzed in the laboratory. Cognitive functioning was measured using the Consortium to Establish a Registry for Alzheimer's Disease Word Learning subtest (CERAD-WL) immediate and delayed memory tests, the Animal Fluency test (AFT), and the Digit Symbol Substitution Test (DSST). Test-specific and global cognition z-scores were calculated based on means and standard deviations of the cognitive test scores. Multivariable linear regression models were constructed to examine the independent association between quartiles of urinary tobacco-specific NNAL and cognitive test-specific and global cognition z-scores controlling for age, sex, race/ethnicity, education level, depressive symptoms, body mass index, systolic blood pressure, urinary creatinine, hypertension, diabetes, alcohol use, and smoking status.

RESULTS

About half of the participants (mean age 69.8 years) were female (52.1%), non-Hispanic White (48.3%), and completed some college and above (49.7%). Multivariable linear regression results showed that participants in the 4th quartile (highest quartile) of urinary NNAL, compared with those in the 1st quartile (lowest quartile), had lower DSST z-scores (β= -0.19; 95% CI: -0.34 - -0.04).

CONCLUSIONS

Tobacco-specific NNAL was negatively associated with processing speed, sustained attention, and working memory in older adults.

Cognitive impairment in schizophrenia: aetiology, pathophysiology, and treatment

Cognitive deficits are a core feature of schizophrenia, account for much of the impaired functioning associated with the disorder and are not responsive to existing treatments. In this review, we first describe the clinical presentation and natural history of these deficits. We then consider aetiological factors, highlighting how a range of similar genetic and environmental factors are associated with both cognitive function and schizophrenia. We then review the pathophysiological mechanisms thought to underlie cognitive symptoms, including the role of dopamine, cholinergic signalling and the balance between GABAergic interneurons and glutamatergic pyramidal cells. Finally, we review the clinical management of cognitive impairments and candidate novel treatments.

The role of frailty, social networks, and depression in self-neglect in an older Chinese population: A cross-sectional descriptive study

OBJECTIVES

To identify the role of frailty, social networks, and depression in self-neglect in an older Chinese population.

METHODS

The study was conducted in 521 older adults recruited from four community healthcare centers in a district in Beijing, China. Participants were investigated by a set of questionnaires.

RESULTS

Frailty (β=0.150, p=0.759) was not associated with self-neglect of older adults. Social isolation (β=1.980, p<0.001) and depression (β=3.606, p<0.001) were both factors associated with self-neglect in older adults.

CONCLUSION

Management of depression and improvement of social networks of older adults should be incorporated into interventional strategies to effectively control self-neglect. Understanding self-neglect and its associated factors will ultimately contribute to the intervention development and well-being of older adults.

Altered white matter functional network in nicotine addiction

Nicotine addiction is a neuropsychiatric disorder with dysfunction in cortices as well as white matter (WM). The nature of the functional alterations in WM remains unclear. The small-world model can well characterize the structure and function of the human brain. In this study, we utilized the small-world model to compare the WM functional connectivity between 62 nicotine addiction participants (called the discovery sample) and 66 matched healthy controls (called the control sample). We also recruited an independent sample comprising 32 nicotine addicts (called the validation sample) for clinical application. The WM functional network data at the network level showed that the nicotine addiction group revealed decreased small-worldness index (σ) and normalized clustering coefficient (γ) compared with healthy controls. For clinical application, the small-world topology of WM functional connectivity could distinguish nicotine addicts from healthy controls (classification accuracy=0.59323, p = 0.0464). We trained abnormal small-world properties on the discovery sample to identify the severity of nicotine addiction, and the identification was successfully applied to the validation sample (classification accuracy=0.65625, p = 0.0106). Our neuroimaging findings provide direct evidence for WM functional changes in nicotine addiction and suggest that the small-world properties of WM function could be qualified as potential biomarkers in nicotine addiction.

The Role of Vascular Risk Factors in Cognitive Impairment and Dementia and Prospects for Prevention

One of the most challenging clinical expressions of population aging is cognitive impairment and dementia. Among risk factors for the development of dementia, modifiable vascular risk factors have emerged as contributors to both vascular and nonvascular types of dementia. Epidemiologic studies have been particularly informative in understanding the link between vascular risks and dementia across the life course. We discuss vascular risks for dementia and cognitive impairment and practical management recommendations.

Relation Between Smoking Status and Subjective Cognitive Decline in Middle Age and Older Adults: A Cross-Sectional Analysis of 2019 Behavioral Risk Factor Surveillance System Data

BACKGROUND

Smoking status may influence subjective cognitive decline (SCD); however, few studies have evaluated this association.

OBJECTIVE

To assess whether smoking status is associated with SCD among middle age and older adults, and to determine if this association is modified by sex at birth.

METHODS

A cross-sectional analysis was conducted using data from the 2019 Behavioral Risk Factor Surveillance System (BRFSS) survey to analyze the relationship between SCD and smoking status (current, recent former, and remote former). Eligible respondents included participants 45 years of age or older who responded to the SCD and tobacco questions of interest. Survey-weighted Poisson regression models were employed to estimate the crude and adjusted prevalence ratios (cPR/aPR) and corresponding 95% confidence intervals (CI) of the association between smoking status and SCD. A Wald test was computed to determine the significance of the interaction term between smoking status and sex (α= 0.05).

RESULTS

There were 136,018 eligible respondents, of which approximately 10% had SCD. There was a graded association between smoking and SCD, with the greatest prevalence of SCD among current smokers (aPR = 1.87; CI: 1.54, 2.28), followed by recent former smokers (aPR = 1.47; 95% CI: 1.02, 2.12), and remote former smokers (aPR = 1.11; 95% CI: 0.93, 1.33) each compared to never smokers. There was no evidence of effect modification by sex (p interaction = 0.73).

CONCLUSION

The consistency of smoking as a risk factor for objective and subjective cognitive decline supports the need for future studies to further the evidence on whether changes to smoking status impacts cognition in middle age.

The role of ethnicity, biological sex, and psychotropic agents in early and late onset Alzheimer's disease

Objective

This study investigates differences in pharmacological and demographic factors among male and female patients with Late-onset Alzheimer's disease (LOAD) and Early-onset Alzheimer's disease (EOAD).

Method

Data are from 10,126 AD patients, 9,290 were diagnosed with LOAD, while 836 were diagnosed with EOAD. Data were collected from the Prisma Health Upstate Alzheimer's patients' registry between 2016 and 2021. The logistic regression analysis was used to assess the association between pharmacological and demographic factors in males and females with LOAD and EOAD.

Results

In the adjusted analysis for males, patients that were administered memantine [odd ratio (OR) = 1.588, 95% CI, 1.175-2.145, p = 0.003], and buspirone [OR = 1.971, 95% CI, 1.221-3.183, p = 0.006] were more likely to be associated with EOAD, while increasing age [OR = 0.816, 95% CI, 0.799-0.834, p < 0.001] was associated with LOAD. Female patients with a history of alcohol (ETOH) use were more likely to be associated with EOAD while increasing age [OR = 0.845, 95% CI, 0.834-0.857, p < 0.001], treatment with memantine [OR = 0.774, 95% CI, 0.627-0.956, p = 0.017], African Americans [OR = 0.621, 95% CI, 0.462-0.835, p = 0.002] and tobacco use [OR = 0.529, 95% CI, 0.424-0.660, p < 0.001] were associated with LOAD.

Conclusion

Our findings identified specific demographic and pharmacological factors associated with males and females with LOAD and EOAD. These findings suggest the need to develop strategies to eliminate disparity in the care of LOAD or EOAD patients.

Nutritional status, alcohol-tobacco consumption behaviour and cognitive decline among older adults in India

Cognition capacity is essentially age-dependent and it is associated with the overall well-being of an individual. The public health aspects of cognitive research primarily focus on the possible delaying of cognitive decline among the older adult population. In this context, using the most recent round of the Longitudinal Ageing Study in India, 2017-2018 data, this study examines the cognition capacity among older adults aged 45 and above subject to their nutritional health and health behaviour (tobacco and alcohol consumption). It is observed that almost one in every tenth individual (10%) above 45 years of age in India shows low cognition scores. Low cognition is much more prevalent among 60 + females than males. Around one-fifth of the underweight older adults (18%) demonstrate low cognition capacity among them. Of those older adults who consume only tobacco, 11% of them demonstrate low cognition than the rest. The partial proportional odds model estimation shows that older adults are at higher risk of developing low cognition with increasing age and beyond age 65, the individuals carry a critically higher risk to experience low cognition. The estimation also shows that with increasing age older adults are higher likely to experience poor cognition independent of nutritional status, but underweight older adults are comparatively more likely to experience low cognition followed by normal and overweight older adults. In terms of alcohol-tobacco consumption behaviour, older adults who consume both are more likely to experience low cognition with increasing age followed by 'only alcohol consumers', and 'only tobacco consumers'.

Contribution of smoking towards the association between socioeconomic position and dementia: 32-year follow-up of the Whitehall II prospective cohort study

Background

There is consistent evidence of social inequalities in dementia but the mechanisms underlying this association remain unclear. We examined the role of smoking in midlife in socioeconomic differences in dementia at older ages.

Methods

Analyses were based on 9951 (67% men) participants, median age 44.3 [IQR=39.6, 50.3] years at baseline in 1985-1988, from the Whitehall II cohort study. Socioeconomic position (SEP) and smoking (smoking status (current, ex-, never-smoker), pack years of smoking, and smoking history score (combining status and pack-years)) were measured at baseline. Counterfactual mediation analysis was used to examine the contribution of smoking to the association between SEP and dementia.

Findings

During a median follow-up of 31.6 (IQR 31.1, 32.6) years, 628 participants were diagnosed with dementia and 2110 died. Analyses adjusted for age, sex, ethnicity, education, and SEP showed smokers (hazard ratio [HR] 1.36 [95% CI 1.10-1.68]) but not ex-smokers (HR 0.95 [95% CI 0.79-1.14]) to have a higher risk of dementia compared to never-smokers; similar results for smoking were obtained for pack-years of smoking and smoking history score. Mediation analysis showed low SEP to be associated with higher risk of dementia (HRs between 1.97 and 2.02, depending on the measure of smoking in the model); estimate for the mediation effect was 16% for smoking status (Indirect Effect HR 1.09 [95% CI 1.03-1.15]), 7% for pack-years of smoking (Indirect Effect HR 1.03 [95% CI 1.01-1.06]) and 11% for smoking history score (Indirect Effect HR 1.06 [95% CI 1.02-1.10]).

Interpretation

Our findings suggest that part of the social inequalities in dementia is mediated by smoking.

Funding

NIH.

Objectively measured secondhand tobacco smoke and cognitive impairment in disability-free older adults

Previous studies have suggested that exposure to secondhand smoke (SHS) may be associated with greater risk of cognitive impairment. However, no longitudinal study has examined the association of serum cotinine (as objective measure of SHS exposure) and cognitive function in older adults. We used data from 2087 non-smoking adults aged≥65 years participating in the ENRICA-2 cohort and free from limitations in Instrumental Activities of Daily Living. Cognitive function was assessed through the Mini-Mental State Examination (MMSE), the Digit Span Backwards subtest (DSBT), the Luria's motor series subtest from the Frontal Assessment Battery, the Trail Making Test A (TMT-A), the Free and Cued Selective Reminding Test (FCSRT), and the Categorical Verbal Fluency Test (CFT) of the 7 min test. Cross-sectional analyses were performed using multivariable logistic and ordered logistic models, while analyses on changes in cognition over time used multivariable repeated-measures mixed-effects models. Compared to the unexposed, those in the highest exposure group (≥0.161 ng/ml) were more likely to have cognitive impairment (MMSE<24) (odds ratio [OR]:1.64; 95% confidence interval [CI]:1.04-2.60) and lower DSBT scores (OR:1.25; 95%CI:1.00-1.57), as well as a non-significant higher odds of a lower score in the Luria test (OR:1.23; 95%CI:0.92-1.64) or episodic memory impairment (FCSRT<12, OR:1.38; 95%CI:0.90-2.11). In longitudinal analyses, those with baseline cotinine ≥0.161 ng/ml showed an increased risk of cognitive impairment (MMSE<24,OR:2.23; 95%CI:1.14-4.33; p-trend across cotinine categories = 0.028) and decreased DSBT (OR:1.23; 95%CI:1.01-1.51; p-trend across cotinine categories = 0.046). Findings show an increased risk of global cognitive impairment and declines in working memory performance in older adults exposed to SHS. More efforts are needed to protect older adults from SHS in areas not covered by smoke-free legislation.

Effect of Short- to Long-Term Exposure to Ambient Particulate Matter on Cognitive Function in a Cohort of Middle-Aged and Older Adults: KoGES

Exposure to ambient air pollution and its threat to human health is a global concern, especially in the elderly population. Therefore, more in-depth studies are required to understand the extent of the harmful effects of particulate matter (PM) based on duration and levels of exposure. An investigation was conducted to determine the association between short- (1-14 days), medium- (1, 3, and 6 months), and long-term (1, 2, and 3 years) exposure to air pollutants (PM_2.5 and PM₁₀) and cognitive function among Koreans (4175 participants, mean age 67.8 years, 55.2% women) aged over 50 years. Higher levels of PM_2.5 exposure for short to long term and PM₁₀ exposure for medium to long term were found to be associated with decreased cognitive function, as indicated by lower scores of the Mini-Mental State Examination adopted in Korean (K-MMSE). There were significant effect modifications by sex, age group, alcohol consumption, physical activity, and smoking status in the association between long-term PM_2.5 and PM₁₀ exposure and cognitive function. These findings, which underscore the importance of the efforts to reduce the exposure levels and durations of air pollutants, especially in the vulnerable elderly population, provide evidence for establishing more stringent policies for air pollution regulations.

Cognition, Aryl Hydrocarbon Receptor Repressor Methylation, and Abstinence Duration-Associated Multimodal Brain Networks in Smoking and Long-Term Smoking Cessation

Cigarette smoking and smoking cessation are associated with changes in cognition and DNA methylation; however, the neurobiological correlates of these effects have not been fully elucidated, especially in long-term cessation. Cognitive performance, percent methylation of the aryl hydrocarbon receptor repressor (AHRR) gene, and abstinence duration were used as references to supervise a multimodal fusion analysis of functional, structural, and diffusion magnetic resonance imaging (MRI) data, in order to identify associated brain networks in smokers and ex-smokers. Correlations among these networks and with smoking-related measures were performed. Cognition-, methylation-, and abstinence duration-associated networks discriminated between smokers and ex-smokers and correlated with differences in fractional amplitude of low frequency fluctuations (fALFF) values, gray matter volume (GMV), and fractional anisotropy (FA) values. Long-term smoking cessation was associated with more accurate cognitive performance, as well as lower fALFF and more GMV in the hippocampus complex. The methylation- and abstinence duration-associated networks positively correlated with smoking-related measures of abstinence duration and percent methylation, respectively, suggesting they are complementary measures. This analysis revealed structural and functional co-alterations linked to smoking abstinence and cognitive performance in brain regions including the insula, frontal gyri, and lingual gyri. Furthermore, AHRR methylation, a promising epigenetic biomarker of smoking recency, may provide an important complement to self-reported abstinence duration.

Comparing relationships between health-related behaviour clustering and episodic memory trajectories in the United States of America and England: a longitudinal study

Background

Health-related behaviours (HRBs) cluster within individuals. Evidence for the association between HRB clustering and cognitive functioning is limited. We aimed to examine and compare the associations between three HRB clusters: “multi-HRB cluster”, “inactive cluster” and “(ex-)smoking cluster” (identified in previous work based on HRBs including smoking, alcohol consumption, physical activity and social activity) and episodic memory trajectories among men and women, separately, in the United States of America (USA) and England.

Methods

Data were from the waves 10–14 (2010–2018) of the Health and Retirement Study in the USA and the waves 5–9 (2010–2018) of the English Longitudinal Study of Ageing in England. We included 17,750 US and 8,491 English participants aged 50 years and over. The gender-specific HRB clustering was identified at the baseline wave in 2010, including the multi-HRB (multiple positive behaviours), inactive and ex-smoking clusters in both US and English women, the multi-HRB, inactive and smoking clusters in US men, and only the multi-HRB and inactive clusters in English men. Episodic memory was measured by a sum score of immediate and delayed word recall tests across waves. For within country associations, a quadratic growth curve model (age-cohort model, allowing for random intercepts and slopes) was applied to assess the gender-stratified associations between HRB clustering and episodic memory trajectories, considering a range of confounding factors. For between country comparisons, we combined country-specific data into one pooled dataset and generated a country variable (0 = USA and 1 = England), which allowed us to quantify between-country inequalities in the trajectories of episodic memory over age across the HRB clusters. This hypothesis was formally tested by examining a quadratic growth curve model with the inclusion of a three-way interaction term (age × HRB clustering × country).

Results

We found that within countries, US and English participants within the multi-HRB cluster had higher scores of episodic memory than their counterparts within the inactive and (ex-)smoking clusters. Between countries, among both men and women within each HRB cluster, faster declines in episodic memory were observed in England than in the USA (e.g., b _{England versus the USA for men: multi-HRB cluster} = -0.05, 95%CI: -0.06, -0.03, b _{England versus the USA for women: ex-smoking cluster} = -0.06, 95%CI: -0.07, -0.04). Additionally, the range of mean memory scores was larger in England than in the USA when comparing means between two cluster groups, including the range of means between inactive and multi-HRB cluster for men (b _{England versus the USA} = -0.56, 95%CI: -0.85, -0.27), and between ex-smoking and multi-HRB cluster for women (b _{England versus the USA} = -1.73, 95%CI: -1.97, -1.49).

Conclusions

HRB clustering was associated with trajectories of episodic memory in both the USA and England. The effect of HRB clustering on episodic memory seemed larger in England than in the USA. Our study highlighted the importance of being aware of the interconnections between health behaviours for a better understanding of how these behaviours affect cognitive health. Governments, particularly in England, could pay more attention to the adverse effects of health behaviours on cognitive health in the ageing population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13785-7.

Social support, social strain and declines in verbal memory: sex-specific associations based on 16-year follow-up of the English Longitudinal Study of Ageing cohort

OBJECTIVES

Previous investigations of cognitive aging have mainly focused on structural aspects of social relations (e.g. network size and composition), thereby neglecting the role of qualitative aspects of social relations. The current longitudinal study examined sex-specific differences in verbal memory decline by measures of perceived relationship quality (social support/strain) by relationship type.

METHOD

In the English Longitudinal Study of Ageing (ELSA), 10,109 participants aged 50-89 years were assessed at wave 1 (baseline: 2002-03) and followed to wave 9 (2017-18). Verbal memory was assessed by immediate and delayed word-recall tasks. Social support/strain was measured by relationship type (spouse; children; family; friends). Random effects within-between (REWB) modelling was used to separate between- and within-person effects. We estimated associations between social support/strain and (1) baseline levels of memory (main effects), and (2) rate of decline in memory (interaction with time-since-baseline).

RESULTS

Longitudinal associations were most prominent for men, specific to relationship type, and showed between- rather than within-person effects. Among men, higher spousal strain was associated with faster memory decline (β_{between-effect×time} = -0.043; 95% CI [-0.084, -0.002]; p = .039), whilst greater support from children was associated with slower decline (β_{between-effect×time} = 0.020; 95% CI [0.002, 0.039]; p = .033). Men with higher strain from friends showed lower baseline memory (β_{between-effect} = -0.382; 95% CI [-0.627, -0.137]; p=.002) and faster decline (β_{between-effect×time} = -0.047; 95% CI [-0.095, 0.000]; p = .051).

CONCLUSION

Between-person differences in social support/strain were modestly associated with memory decline, especially among men.

Alteration of Gut Microbiota in Alzheimer's Disease and Their Relation to the Cognitive Impairment

BACKGROUND

Dysbiosis of gut microbiota has been reported to be enrolled in the pathogenesis of Alzheimer's disease (AD). However, there is a lack of relevant studies on this topic in Egyptian patients with AD.

OBJECTIVE

To investigate different species of gut microbiota in Egyptian patients with AD and correlate microbiota bacterial abundance with clinical data.

METHODS

The study included 25 patients with AD and 25 healthy volunteers as age and sex-matched controls. Clinical data was taken for each patient, including medical history and examination; Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were assessed for each participant. Bacterial DNA was extracted from stool, and abundance quantified via qPCR using 16S rRNA group-specific primers.

RESULTS

Akkermansia, Enterobacteria, Bacteroidetes, Bacillus cereus, Prevotella, and Clostridium cluster IV were more abundant in the AD group than in the control group, although there was significantly less abundance of Bifidobacterium spp., Firmicutes, and Actinobacteria in patients with AD than in controls, whereas no such significance was found for lactic acid bacteria between both groups. Lactic acid bacteria and Prevotella abundance was negatively correlated with cognitive impairment (p = 0.03 with MMSE, and p = 0.03 with MoCA). Prevotella abundance was positively correlated with age of onset and duration of illness and negatively correlated with smoking and coronary heart disease (p = 0.007, p = 0.03, p = 0.035, and p = 0.047, respectively).

CONCLUSION

The current work highlighted a significant relationship between AD and gut microbiota dysbiosis. A higher abundance of Prevotella species and lactic acid bacteria was correlated with cognition.

The Effects of “Diet–Smoking–Gender” Three-Way Interactions on Cognitive Impairment among Chinese Older Adults

Investigations on gender variations in the risk factors of cognitive impairment are required to promote future precision medicine among older adults, as well as to contribute to a better understanding of the “male–female health-survival paradox”. With this study, we aimed to investigate the effects of “diet–smoking–gender” three-way interactions on cognitive impairments among Chinese older adults. We conducted a 16-year prospective cohort study among 15,953, 15,555, 16,849, 9716, 7116, and 13,165 older adults from the 2002, 2005, 2008–2009, 2011–2012, 2014, and 2017–2018 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), respectively. Cognitive impairment was measured by the Mini-Mental State Examination (MMSE). The dietary diversity score (DDS) was calculated using the CLHLS food frequency questionnaire. Generalized estimating equations (GEE) were used to assess the “diet–smoking–gender” three-way interaction effects on cognitive impairment across the six waves of CLHLS. We found that higher dietary diversity was associated with lower probability of cognitive impairment among older adults (OR = 0.92; 95%CI = 0.90, 0.98). However, smoking behavior may negatively influence the protective effect of higher dietary diversity on cognitive function among females (OR = 1.26; 95%CI = 1.07, 1.49). Our findings imply that we should take gender differences and lifestyle behaviors into consideration in implementing dietary interventions to improve cognitive function among older adults.

Ethnic-Specific Type 2 Diabetes Risk Factor PAX4 R192H Is Associated with Attention-Specific Cognitive Impairment in Chinese with Type 2 Diabetes

Background: Type 2 diabetes mellitus (T2DM) has been shown to increase the risks of cognitive decline and dementia. Paired box gene 4 (PAX4), a transcription factor for beta cell development and function, has recently been implicated in pathways intersecting Alzheimer’s disease and T2DM. Objective: In this report, we evaluated the association of the ethnic-specific PAX4 R192H variant, a T2DM risk factor for East Asians which contributes to earlier diabetes onset, and cognitive function of Chinese T2DM patients. Methods: 590 Chinese patients aged 45–86 from the SMART2D study were genotyped for PAX4 R192H variation using Illumina OmniExpress-24 Array. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) which had been validated in the Singapore population was administered to assess five cognitive domains: immediate memory, visuospatial/constructional, language, attention, and delayed memory. Multiple linear regression was used to assess the association of the R192H risk allele and cognitive domains. Results: Patients with two PAX4 R192H risk alleles showed significantly lower attention index score (β= –8.46, 95% CI [–13.71, –3.21], p = 0.002) than patients with wild-type alleles after adjusting for age, gender, diabetes onset age, HbA1c, body-mass index, renal function, lipid profiles, systolic blood pressure, metformin usage, smoking history, education level, Geriatric Depression Scale score, and presence of APOE ɛ4 allele. Conclusion: Ethnic-specific R192H variation in PAX4 is associated with attention-specific cognitive impairment in Chinese with T2DM. Pending further validation studies, determining PAX4 R192H genotype may be helpful for early risk assessment of early-onset T2DM and cognitive impairment to improve diabetes care.

Cognitive impairment and edentulism among older adults: an observational study using claims data

Background

The scientific link between mastication strength and cognitive function has not yet been strongly corroborated in population studies. Utilizing large-scale claims, we aim to investigate the association between edentulism and cognitive impairment in older American adults.

Methods

Using de-identified claims from a commercial insurer from 2015–2019, we conducted a retrospective cohort study using multilevel regression models to evaluate the association between denture status and clinically diagnosed cognitive impairment. Secondary analysis included symptomatic cognitive impairment in the outcome.

Results

Adjusting for individual-level risk factors, denture status was significantly associated with clinical cognitive impairment with odds ratios of 1.13 (95%CI: 1.02–1.25) and 1.26, (95%CI: 1.09–1.45) for complete dentures on one or both jaws, respectively. Including symptomatic cognitive impairment in the analysis did not substantially change our fundamental findings.

Conclusion

Prevention and treatment of oral diseases should be considered a key component in preserving the overall wellness of older adults.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-02985-w.

Early to Midlife Smoking Trajectories and Cognitive Function in Middle-Aged US Adults: the CARDIA Study

BACKGROUND

Smoking starts in early adulthood and persists throughout the life course, but the association between these trajectories and midlife cognition remains unclear.

OBJECTIVE

Determine the association between early to midlife smoking trajectories and midlife cognition.

DESIGN

Prospective cohort study.

PARTICIPANTS

Participants were 3364 adults (mean age = 50.1 ± 3.6, 56% female, 46% Black) from the Coronary Artery Risk Development in Young Adults (CARDIA) study: 1638 ever smokers and 1726 never smokers.

MAIN MEASURES

Smoking trajectories were identified in latent class analysis among 1638 ever smokers using smoking measures every 2-5 years from baseline (age 18-30 in 1985-1986) through year 25 (2010-2011). Poor cognition was based on cognitive domain scores ≥ 1 SD below the mean on tests of processing speed (Digit Symbol Substitution Test), executive function (Stroop), and memory (Rey Auditory Verbal Learning Test) at year 25.

RESULTS

Five smoking trajectories emerged over 25 years: quitters (19%), and minimal stable (40%), moderate stable (20%), heavy stable (15%), and heavy declining smokers (5%). Heavy stable smokers showed poor cognition on all 3 domains compared to never smoking (processing speed AOR = 2.22 95% CI 1.53-3.22; executive function AOR = 1.58 95% CI 1.05-2.36; memory AOR = 1.48 95% CI 1.05-2.10). Compared to never smoking, both heavy declining (AOR = 1.95 95% CI 1.06-3.68) and moderate stable smokers (AOR = 1.56 95% CI 1.11-2.19) exhibited slower processing speed, and heavy declining smokers additionally had poor executive function. For minimal stable smokers (processing speed AOR = 1.12 95% CI 0.85-1.51; executive function AOR = 0.97 95% CI 0.71-1.31; memory AOR = 1.21 95% CI 0.94-1.55) and quitters (processing speed AOR = 0.96 95% CI 0.63-1.48; executive function AOR = 0.98 95% CI 0.63-1.52; memory AOR = 0.97 95% CI 0.67-1.39), no association was observed.

CONCLUSIONS

The association between early to midlife smoking trajectories and midlife cognition was dose-dependent. Results underscore the cognitive health risk of moderate and heavy smoking and the potential benefits of quitting on cognition, even in midlife.

Ebselen prevents cigarette smoke-induced cognitive dysfunction in mice by preserving hippocampal synaptophysin expression

Background

Cigarette smoking (CS) is the leading cause of chronic obstructive pulmonary disease (COPD). The “spill-over” of pulmonary inflammation into the systemic circulation may damage the brain, leading to cognitive dysfunction. Cessation of CS can improve pulmonary and neurocognitive outcomes, however, its benefit on the neuroinflammatory profile remains uncertain. Here, we investigate how CS exposure impairs neurocognition and whether this can be reversed with CS cessation or an antioxidant treatment.

Methods

Male BALB/c mice were exposed to CS (9 cigarettes/day for 8 weeks) followed by 4 weeks of CS cessation. Another cohort of CS-exposed mice were co-administrated with a glutathione peroxidase mimetic, ebselen (10 mg/kg) or vehicle (5% CM-cellulose). We assessed pulmonary inflammation, spatial and working memory, and the hippocampal microglial, oxidative and synaptic profiles.

Results

CS exposure increased lung inflammation which was reduced following CS cessation. CS caused spatial and working memory impairments which were attributed to hippocampal microglial activation and suppression of synaptophysin. CS cessation did not improve memory deficits or alter microglial activation. Ebselen completely prevented the CS-induced working and spatial memory impairments, which was associated with restored synaptophysin expression without altering microglial activation.

Conclusion

We were able to model the CS-induced memory impairment and microglial activation seen in human COPD. The preventative effects of ebselen on memory impairment is likely to be dependent on a preserved synaptogenic profile. Cessation alone also appears to be insufficient in correcting the memory impairment, suggesting the importance of incorporating antioxidant therapy to help maximising the benefit of cessation.

More than a third of middle-aged adults (50-65) have understated executive dysfunction

OBJECTIVES

Understated executive dysfunction (UED) is predictive of cognitive decline and death. We aimed to assess the prevalence of UED, assessed with the clock-drawing test (CDT) and the Frontal Assessment Battery (FAB) in middle-aged adults and to investigate associated characteristics.

METHODS

Cross-sectional analysis of data on 516 community-dwellers aged 50-65, lacking cognitive complaints, who were included prospectively (2010-2017) after a multidimensional geriatric assessment at a "healthy ageing" outpatient clinic. Age- and educational-level-adjusted logistic models were used to assess factors associated with UED.

RESULTS

The CDT and FAB were impaired in 27.7% and 14.7% of the participants (median age: 59.7 years). The prevalence [95% confidence interval (CI)] of UED was 36.2% [32.2-40.5%]. After adjustment for age and education, participants with UED were more likely to be obese (odds ratio [95%CI] = 1.89 [1.12-3.19], P = 0.02), and to have a metabolic syndrome (1.98 [1.06-3.72], P = 0.03).

CONCLUSION

More than one third of middle-aged adults without cognitive complaints have UED, which was linked to obesity and metabolic syndrome. Cognitive screening tests targeting executive functions might be useful for early detection of UED and the initiation of multidomain interventions improving cognitive performance.

Mid-life epigenetic age, neuroimaging brain age, and cognitive function: coronary artery risk development in young adults (CARDIA) study

The proportion of aging populations affected by dementia is increasing. There is an urgent need to identify biological aging markers in mid-life before symptoms of age-related dementia present for early intervention to delay the cognitive decline and the onset of dementia. In this cohort study involving 1,676 healthy participants (mean age 40) with up to 15 years of follow up, we evaluated the associations between cognitive function and two classes of novel biological aging markers: blood-based epigenetic aging and neuroimaging-based brain aging. Both accelerated epigenetic aging and brain aging were prospectively associated with worse cognitive outcomes. Specifically, every year faster epigenetic or brain aging was on average associated with 0.19-0.28 higher (worse) Stroop score, 0.04-0.05 lower (worse) RAVLT score, and 0.23-0.45 lower (worse) DSST (all false-discovery-rate-adjusted p <0.05). While epigenetic aging is a more stable biomarker with strong long-term predictive performance for cognitive function, brain aging biomarker may change more dynamically in temporal association with cognitive decline. The combined model using epigenetic and brain aging markers achieved the highest accuracy (AUC: 0.68, p<0.001) in predicting global cognitive function status. Accelerated epigenetic age and brain age at midlife may aid timely identification of individuals at risk for accelerated cognitive decline and promote the development of interventions to preserve optimal functioning across the lifespan.

Examining the impact of socioeconomic status, demographic characteristics, lifestyle and other risk factors on adults' cognitive functioning in developing countries: an analysis of five selected WHO SAGE Wave 1 Countries

BACKGROUND

Though extensive studies have been conducted on assessing the predictors of cognitive functioning among older adults in small community-based samples, very few studies have focused on understanding the impact of socioeconomic status (SES), demographic characteristics and other risk factors such as lifestyle and chronic diseases on the cognitive functioning among adults of all ages in a nationally representative population-based sample across low- and middle-income countries. This study, therefore, seeks to evaluate the impact of SES, demographic characteristics and risk factors on the cognitive functioning of adults across all ages in five selected developing countries.

METHODS

Data from 12,430 observations obtained from the WHO Study on Global AGEing and Adult Health (SAGE) Wave 1; consisting of 2,486 observations each for China, Ghana, India, the Russian Federation, and South Africa, were used for the study. A meta-regression and a five-step hierarchical linear regression were used to analyze the data, with cognitive functioning as the dependent variable. Independent variables used in this study include SES; assessed by household income and education, demographic characteristics, other risk factors such as lifestyle, self-reported memory difficulty and chronic diseases.

RESULTS

This study found that SES and lifestyle significantly predicted cognitive functioning in all the five selected countries as obtained by the pooled results of the meta-regression analysis. The hierarchical linear regression results also revealed that demographic characteristics such as age, type of residency, and self-reported memory difficulty significantly impact cognitive functioning in China, Ghana, Russia, and South Africa.

CONCLUSION

The findings in this study provide new insights for policymakers, caregivers, parents, and individuals, especially those in developing countries, to implement policies and actions targeted at improving SES and eliminating risk factors associated with cognitive decline, as these measures could help improve the cognitive functioning among their populations.

The Brain-Derived Neurotrophic Factor Functional Polymorphism and Hand Grip Strength Impact the Association between Brain-Derived Neurotrophic Factor Levels and Cognition in Older Adults in the United States

INTRODUCTION

Aging is associated with subtle cognitive decline in attention, memory, executive function, processing speed, and reasoning. Although lower brain-derived neurotrophic factor (BDNF) has been linked to cognitive decline among older adults, it is not known if the association differs among individuals with various BDNF Val66Met (rs6265) genotypes. In addition, it is not clear whether these associations vary by hand grip strength or physical activity (PA).

METHODS

A total of 2904 older adults were included in this study using data from the Health and Retirement Study. Associations between serum BDNF and measures of cognitive function were evaluated using multivariable linear regression models stratified by Met allele status. PA and hand grip strength were added to the model to evaluate whether including these variables altered associations between serum BDNF and cognition.

RESULTS

Mean age was 71.4 years old, and mean body mass index was 28.3 kg/m². Serum BDNF levels were positively associated with higher total cognitive score (beta = 0.34, p = .07), mental status (beta = 0.16, p = .07), and word recall (beta = 0.22, p =.04) among Met carriers, while serum BDNF levels were negatively associated with mental status (beta = -0.09, p = .07) among non-Met carriers. Furthermore, associations changed when hand grip strength was added to the model but not when PA was added to the model.

CONCLUSIONS

The BDNF Val66Met variant may moderate the association between serum BDNF levels and cognitive function in older adults. Furthermore, such associations differ according to hand grip strength but not PA.

Impact of Cigarette Smoking and Its Interaction with Hypertension and Diabetes on Cognitive Function in Older Americans

BACKGROUND

The detrimental impact of tobacco smoking on brain health is well recognized.

OBJECTIVE

To evaluate whether smoking acts synergistically with hypertension and diabetes to influence cognitive performance.

METHODS

We performed a cross-sectional analysis using the US National Health and Nutrition Examination Survey. Participants were tested for serum cotinine, a validated cigarette smoking/exposure biomarker, and had standardized blood pressure and hemoglobin A1c measurements. Participants were administered four cognitive tests: Digit Symbol Substitution (DSST), Animal Fluency, Immediate Recall, and Delayed Recall. Multivariable linear regression models adjusted for demographics and confounders evaluated the association of cotinine with cognition. Interaction testing evaluated effect modification by hypertension, diabetes, and their continuous measures (systolic blood pressure and hemoglobin A1c).

RESULTS

For 3,007 participants, mean age was 69.4 years; 54% were women. Using cotinine levels, 14.9% of participants were categorized as active smokers. Higher cotinine levels were associated with worse DSST performance when modeling cotinine as a continuous variable (β, -0.70; 95% CI, -1.11, -0.29; p < 0.01) and when categorizing participants as active smokers (β, -5.63; 95% CI, -9.70, -1.56; p < 0.01). Cotinine was not associated with fluency or memory. Effect modification by hypertension and diabetes were absent, except that cotinine was associated with worse Immediate Recall at lower blood pressures.

CONCLUSION

Higher levels of a smoking and secondhand exposure biomarker were associated with worse cognitive performance on a multidomain test. Overall, the relationship of cotinine with cognition was not contingent on or amplified by hypertension or diabetes; smoking is detrimental for brain health irrespective of these comorbidities.

Alcohol use disorder and treatment receipt among individuals aged 50 years and older: Other substance use and psychiatric correlates

OBJECTIVE

Alcohol use disorder (AUD) is increasing among U.S. individuals aged 50+. We examined associations of past-year AUD with other substance use and any mental illness (AMI) and associations of past-year AUD treatment receipt with other substance use, AMI, and mental health treatment receipt among those with AUD.

METHODS

Data came from the 2015-2018 National Survey on Drug Use and Health (N = 35,229). We used multivariable logistic regression analysis to examine the research questions.

RESULTS

In the 50+ age group, 58.7% of women and 66.9% of men reported past-year alcohol use and 2.0% of women and 4.9% of men had AUD. Those with any alcohol use problem (binge drinking, heavy drinking, or AUD) had higher odds of other substance use or use disorders; however, AMI was associated with higher odds of AUD only (AOR = 2.54, 95% CI = 2.15-3.00, AOR = 2.63, 95% CI = 1.98-3.50, and AOR = 3.13, 95% CI = 2.19-4.48, respectively, for mild, moderate, and serious mental illness). Only 7.9% of those with AUD received any alcohol treatment. AMI and mental health treatment were associated with higher odds of alcohol treatment receipt (AOR = 5.18, 95% CI = 2.13-12.55, AOR = 4.14, 95% CI = 1.51-11.30, and AOR = 2.91, 95% CI = 1.41-6.00, respectively, for moderate mental illness, serious mental illness, and mental health treatment receipt).

CONCLUSION

The findings show that fewer than one in 10 older adults with AUD received any alcohol treatment and suggest that individuals need education on alcohol harms and assistance in accessing alcohol treatment. Combined mental health and alcohol treatment at a single location may improve access and use.

Sociodemographic, Lifestyle, Physical, and Psychosocial Determinants of Cognitive Reserve

BACKGROUND

Cognitive reserve aims to explain individual differences in the susceptibility to the functional impact of dementia in the presence of equal amount of neuropathological damage. It is thought to be shaped by a combination of innate individual differences and lifetime exposures. Which determinants are associated with cognitive reserve remains unknown.

OBJECTIVE

The objective of this study was to investigate the associations of sociodemographic, lifestyle, physical, and psychosocial determinants with cognitive reserve, and potential sex differences.

METHODS

This cross-sectional study included 4,309 participants from the Rotterdam Study (mean age 63.9±10.7) between 2006-2016. Participants completed five cognitive tests and a brain MRI-scan. Cognitive reserve was defined as a latent variable that captures variance common across five cognitive tests, while adjusting for demographic and MRI-inferred neuropathological factors. The associations of potential determinants and cognitive reserve, adjusted for relevant confounders, were assessed with structural equation models.

RESULTS

Current smoking (adjusted mean difference: -0.31, 95%confidence interval -0.42; -0.19), diabetes mellitus (-0.25, -0.40; -0.10) and depressive symptoms (-0.07/SD, -0.12; -0.03) were associated with a lower cognitive reserve whereas alcohol use (0.07/SD, 0.03; 0.12) was associated with higher cognitive reserve. Only smoking was associated with cognitive reserve in both men and women. Employment, alcohol use, diabetes, history of cancer, COPD, and depressive symptoms were only associated with cognitive reserve in women.

CONCLUSION

Our study found that current smoking, diabetes mellitus, and depressive symptoms were associated with a lower cognitive reserve, whereas more alcohol use was associated with a higher cognitive reserve, but with clear differences between men and women.

Neuroprotective effects of Olea europaea L. fruit extract against cigarette smoke-induced depressive-like behaviors in Sprague-Dawley rats

Depression is broadly acclaimed as a mental health anomaly and despite advancements in the development of antidepressant drugs, they are linked with side effects. Dietary modifications and medicinal plants like olives can be used as effective strategies due to their antioxidant, immune-modulatory, antiinflammatory, and anticonvulsant properties. Considering the compositional alterations in olive fruits during ripening, the antidepressant potential of olive fruits at different degrees of ripeness, that is, un-ripened (green) and ripened (black) was investigated. Rats were randomly divided into five groups: G₀ (Normal diet), G₁ (Normal diet + smoke exposure (SE), G₂ (Normal diet + SE + Citalopram), G₃ (Normal diet + SE + Green olive extract), and G₄ (Normal diet + SE + Black olive extract). Depressive-like behaviors were induced in all groups through cigarette smoke exposure except G₀ . Green and black olive extracts prevented depressive behaviors by reducing the immobility time of rats in forced swim test and tail suspension test while increased the latency to respond in hot plate assay. Moreover, lipid peroxidation in brain tissue was reduced with citalopram, green, and black olive extracts. Additionally, treatments also enhanced the antioxidant pool of brain tissues. Histological examination revealed that olive extracts and citalopram prevented cigarette smoke-induced moderate to severe necrosis and congestion in the brain parenchyma and elucidated antidepressant potential by improving the expression of monoamine oxidase-A, solute carrier family 6 member 4, and brain-derived neurotrophic factor genes. Conclusively, olives may act as a promising antidepressant agent in ameliorating cigarette smoke-induced depressive-like behaviors. PRACTICAL APPLICATIONS: Olive extracts at both ripening stages revealed an antidepressant-like effect almost similar to the standard antidepressant drug and also prevented oxidative damages. Therefore, from the current findings, it can be recommended that food ingredients with antidepressant potential like olives should be incorporated in future interventions to combat depression/psychiatric anomalies and diet therapy should be encouraged to alleviate lifestyle-related disorders.