Smoking cessation and Alzheimer's disease: facts, fallacies and promise

Nicotine Use Disorder in Older Adults

Nicotine is one of the most abused substances worldwide. Just as in adolescence and adulthood, tobacco use is also problematic in the elderly. Older people are more vulnerable to smoking consequences because of the additive effects of smoke. Cardiovascular diseases are the most common health problems associated with smoking; however, other systems are also affected, including the respiratory, nervous, integumentary, and many other systems. Smoking cessation is a difficult task especially in the elderly; therefore, physicians should encourage older patients to quit with every patient-physician encounter by offering counseling and replacement therapy.

Relationship of Cigarette Smoking and Time of Quitting with Incident Dementia and Cognitive Decline

OBJECTIVES

Understanding how dementia risk is impacted by timing of smoking cessation has public health implications for prevention efforts. We investigated the relationship of cigarette smoking and cessation with dementia risk and cognitive decline in the Atherosclerosis Risk in Communities (ARIC) study.

DESIGN

Ongoing prospective cohort study.

SETTING

Begun in 1987-1989, ARIC was conducted in four US communities.

PARTICIPANTS

A total of 13 002 men and women (25% African American) aged 52 to 75 years.

MEASUREMENTS

All-cause dementia was defined using standardized algorithms incorporating longitudinal cognitive data, proxy report, and hospital and death certificate dementia codes. Cognitive decline was measured using a composite cognitive score created from three tests measured at two time points (1996-1998 and 2011-2013). Smoking and cessation status were defined by self-report using data from 1987-1989 (visit 1) and 1996-1998 (visit 4). Incident dementia risk and differences in cognitive change by smoking status were estimated with Cox proportional hazards and linear regression models, respectively. To address smoking-related attrition, cognitive scores were imputed for living participants with incomplete cognitive testing.

RESULTS

The proportion of never, former, and current smokers was 44%, 41%, and 14%; 79% of former smokers quit 9 years or more before baseline. A total of 1347 participants developed dementia. After adjustment, compared with never smoking, the hazard ratio for all-cause dementia for current smoking was 1.33 (95% confidence interval [CI] = 1.12-1.59) and for recent quitting (<9 y before baseline) was 1.24 (95% CI = 1.01-1.52). Quitting 9 years or more before baseline was not associated with dementia. We found no differences in rates of cognitive decline by smoking status.

CONCLUSION

Although quitting at any time suggested benefit, dementia risk depended on time since smoking cessation. Our study highlights the importance of early midlife cessation to decrease dementia risk. J Am Geriatr Soc 68:337-345, 2020.

The Convention on the Rights of Persons with Disabilities as a tobacco control tool in the mental health setting

BACKGROUND

Smoking rates remain high among people with mental health conditions, even though smoking contributes to negative mental health outcomes and is a leading cause of mortality. Many mental health facilities are not covered by smoke-free laws or do not encourage smoking cessation, and people with mental health conditions are often targeted in tobacco industry promotions.

OBJECTIVE

To analyse how the Convention on the Rights of Persons with Disabilities (CRPD), to which most countries are a Party, obliges State Parties to review policies and practices for tobacco control in the mental health setting.

METHOD

Analysis of CRPD Articles relevant to smoking and mental health.

RESULTS

The CRPD contains several provisions that oblige State Parties to address the issue of smoking and mental health, particularly in relation to quit services, smoke-free policies in mental health facilities, health education focused on correcting misperceptions about smoking and mental health, and protecting people with mental health conditions from tobacco industry targeting.

CONCLUSIONS

The CRPD is a potentially powerful tool to promote tobacco control in the mental health context.

Smoking and increased Alzheimer's disease risk: a review of potential mechanisms

BACKGROUND

Cigarette smoking has been linked with both increased and decreased risk for Alzheimer's disease (AD). This is relevant for the US military because the prevalence of smoking in the military is approximately 11% higher than in civilians.

METHODS

A systematic review of published studies on the association between smoking and increased risk for AD and preclinical and human literature on the relationships between smoking, nicotine exposure, and AD-related neuropathology was conducted. Original data from comparisons of smoking and never-smoking cognitively normal elders on in vivo amyloid imaging are also presented.

RESULTS

Overall, literature indicates that former/active smoking is related to a significantly increased risk for AD. Cigarette smoke/smoking is associated with AD neuropathology in preclinical models and humans. Smoking-related cerebral oxidative stress is a potential mechanism promoting AD pathology and increased risk for AD.

CONCLUSIONS

A reduction in the incidence of smoking will likely reduce the future prevalence of AD.

Systematic review and meta-analysis of the economic impact of smoking bans in restaurants and bars

AIMS

To review systematically the literature on the economic impact of smoking bans in bars and restaurants and provide an estimate of the impact size using meta-analysis.

METHODS

Studies were identified by systematic database searches and screening references of reviews and relevant studies. Google and web-pages of tobacco control agencies were also searched. The review identified 56 studies using absolute sales, sales ratio or employment data and employing regression methods to evaluate the impact of smoking bans in the United States, Australia or in countries in South America or Europe. The meta-analysis included 39 comparable studies, with 129 cases identified based on the outcome measure, scope of the ban, type of establishment and geographical location. Methodological quality was assessed based on four pre-determined criteria. Study and case selection and data extraction were conducted independently by two researchers.

RESULTS

Random-effects meta-analysis of all cases showed no associations between smoking bans and changes in absolute sales or employment. An increase in the share of bar and restaurant sector sales in total retail sales was associated with smoking bans [0.23 percentage-points; 95% confidence interval (CI) 0.08-0.375]. When cases were separated by business type (bars or restaurants or wider hospitality including bars and restaurants), some differential impacts emerged.

CONCLUSIONS

Meta-analysis of the economic impact of smoking bans in hospitality sector showed overall no substantial economic gains or losses. Differential impacts were observed across individual business types and outcome variable, but at aggregate level these appear to balance out.

Interactive effects of chronic cigarette smoking and age on brain volumes in controls and alcohol-dependent individuals in early abstinence

Chronic alcohol-use disorders (AUDs) have been shown to interact with normal age-related volume loss to exacerbate brain atrophy with increasing age. However, chronic cigarette smoking, a highly co-morbid condition in AUD and its influence on age-related brain atrophy have not been evaluated. We performed 1.5 T quantitative magnetic resonance imaging in non-smoking controls [non-smoking light drinking controls (nsCONs); n = 54], smoking light drinking controls (sCONs, n = 34), and one-week abstinent, treatment-seeking alcohol-dependent (ALC) non-smokers (nsALCs, n = 35) and smokers (sALCs, n = 43), to evaluate the independent and interactive effects of alcohol dependence and chronic smoking on regional cortical and subcortical brain volumes, emphasizing the brain reward/executive oversight system (BREOS). The nsCONs and sALCs showed greater age-related volume losses than the nsALCs in the dorsal prefrontal cortex (DPFC), total cortical BREOS, superior parietal lobule and putamen. The nsALCs and sALCs demonstrated smaller volumes than the nsCONs in most cortical region of interests (ROIs). The sCONs had smaller volumes than the nsCONs in the DPFC, insula, inferior parietal lobule, temporal pole/parahippocampal region and all global cortical measures. The nsALCs and sALCs had smaller volumes than the sCONs in the DPFC, superior temporal gyrus, inferior and superior parietal lobules, precuneus and all global cortical measures. Volume differences between the nsALCs and sALCs were observed only in the putamen. Alcohol consumption measures were not related to volumes in any ROI for ALC; smoking severity measures were related to corpus callosum volume in the sCONs and sALCs. The findings indicate that consideration of smoking status is necessary for a better understanding of the factors contributing to regional brain atrophy in AUD.

Greater regional brain atrophy rate in healthy elderly subjects with a history of cigarette smoking

BACKGROUND

Little is known about the effects of cigarette smoking on longitudinal brain morphological changes in the elderly. This study investigated the effects of a history of cigarette smoking on changes in regional brain volumes over 2 years in healthy, cognitively intact elderly individuals. We predicted that individuals with a history of cigarette smoking, compared with never smokers, demonstrate greater rate of atrophy over 2 years in regions that manifest morphological abnormalities in the early stages of Alzheimer's disease (AD), as well as in the extended brain reward/executive oversight system (BREOS), which is implicated in the development and maintenance of substance use disorders.

METHODS

Participants were healthy, cognitively normal elderly control subjects (75.9 ± 4.8 years of age) with any lifetime history of cigarette smoking (n = 68) or no history of smoking (n = 118). Data were obtained through the Alzheimer Disease Neuroimaging Initiative from 2005 to 2010. Participants completed four magnetic resonance scans over 2 years. A standardized protocol using high-resolution three-dimensional T1-weighted sequences at 1.5 T was used for structural imaging and regional brain volumetric analyses.

RESULTS

Smokers demonstrated a significantly greater atrophy rate over 2 years than nonsmokers in multiple brain regions associated with the early stages of AD, as well as in the BREOS system. Groups did not differ on the rate of global cortical atrophy.

CONCLUSIONS

A history of cigarette smoking in this healthy elderly cohort was associated with decreased structural integrity of multiple brain regions, which manifested as a greater rate of atrophy over 2 years in regions specifically affected by incipient AD as well as chronic substance abuse.

A comprehensive assessment of neurocognition in middle-aged chronic cigarette smokers

BACKGROUND

The majority of studies investigating the neurocognitive consequences of chronic smoking have been conducted with adults 60 years and older. Therefore, the scope of neurocognitive dysfunction associated with chronic cigarette smoking in middle age (i.e., 30-60 age range) has not been fully delineated.

METHODS

Twenty-seven (44±9 years of age; 4 females) non-smoking and 30 smoking (49±8 years of age; 4 females) participants completed a comprehensive neurocognitive battery and measures of fine motor dexterity and postural stability. All participants were free of biomedical or psychiatric conditions that may have influenced neurocognitive and motor function.

RESULTS

Smokers performed significantly worse than non-smokers on the following domains: auditory-verbal and visuospatial learning, visuospatial memory, cognitive efficiency, executive skills, general intelligence, processing speed, fine motor dexterity and postural stability. The differences between smokers and non-smokers evidenced moderate to strong effect sizes and were not mediated by age, education, vocational level, estimated verbal intelligence or alcohol consumption. In smokers, a greater number of lifetime years of smoking was related to poorer performance on measures of cognitive efficiency, processing speed and visuospatial skills.

CONCLUSIONS

Results from this middle-aged cohort replicated previous research and provides novel findings indicating that chronic smoking was associated with inferior performance on measures of general intelligence, visuospatial learning and memory and fine motor dexterity. Research that relates measures of neurobiological function/integrity to neurocognition is needed to better understand the mechanisms contributing to the poorer performance across multiple domains demonstrated by smokers.

The nicotinic acetylcholine receptor: smoking and Alzheimer's disease revisited

Epidemiological studies regarding Alzheimer's disease (AD) in smokers currently suggest inconsistent results. The clinicopathological findings also vary as to how AD pathology is affected by smoking behavior. Even though clinicopathological, functional, and epidemiological studies in humans do not present a consistent picture, much of the in vitro data implies that nicotine has neuroprotective effects when used in neurodegenerative disorder models. Current studies of the effects of nicotine and nicotinic agonists on cognitive function in both the non-demented and those with AD are not convincing. More data is needed to determine whether repetitive activation of nAChR with intermittent or acute exposure to nicotine, acute activation of nAChR, or long-lasting inactivation of nAChR secondary to chronic nicotine exposure will have a therapeutic effect and/or explain the beneficial effects of those types of drugs. Other studies show multifaceted connections between nicotine, nicotinic agonists, smoking, and nAChRs implicated in AD etiology. Although many controversies still exist, ongoing studies are revealing how nicotinic receptor changes and functions may be significant to the neurochemical, pathological, and clinical changes that appear in AD.

Brain imaging of nicotinic receptors in Alzheimer's disease

Neuronal nicotinic acetylcholine receptors (nAChRs) are a family of ligand-gated ion channels which are widely distributed in the human brain. Several lines of evidence suggest that two major subtypes (α4β2 and α7) of nAChRs play an important role in the pathophysiology of Alzheimer's disease (AD). Postmortem studies demonstrated alterations in the density of these subtypes of nAChRs in the brain of patients with AD. Currently, nAChRs are one of the most attractive therapeutic targets for AD. Therefore, several researchers have made an effort to develop novel radioligands that can be used to study quantitatively the distribution of these two subtypes in the human brain with positron emission tomography (PET) and single-photon emission computed tomography (SPECT). In this paper, we discuss the current topics on in vivo imaging of two subtypes of nAChRs in the brain of patients with AD.