Smoking and cognitive change from age 11 to 66 years: a confirmatory investigation

Association Between Smoking and Amnesia in Southwest Iran: A Population-Based Cross-sectional Study

BACKGROUND

Amnesia is a cognitive impairment that manifests as a deficit in the retrieval of previous memories and the acquisition of novel information. Limited research, especially in Iran, exists on the risk factors of amnesia, and smoking might be linked to a greater likelihood of experiencing memory issues and cognitive decline, including amnesia. The aim of this study was to explore the risk factors associated with amnesia and the connection between smoking and amnesia. Study Design: A population-based cross-sectional study.

METHODS

This study was conducted at the baseline of the Hoveyzeh cohort study on adults aged 35-70 years in southwest Iran between 2016 and 2018. The required data on socioeconomic factors, demographic characteristics, history of stroke, history of epilepsy, and history of head trauma were collected from the participants. The relationship between smoking and amnesia was assessed, and multiple logistic regression was employed to account for potential confounding variables.

RESULTS

The mean age of the participants was 48.83±9.20 years, and 39% were male. The overall prevalence of amnesia was 4.2% (95% confidence interval [CI]: 3.8-4.6). The odds of having amnesia were significantly higher in smokers than in nonsmokers (adjusted odds ratio=1.52 [95% CI: 1.21-1.91]). Additionally, several other factors, including age, education level, type of residence, history of stroke, epilepsy, and history of trauma, were associated with amnesia.

CONCLUSION

Our investigations revealed a direct correlation between smoking and amnesia. To gain a more comprehensive understanding of the underlying mechanisms of these associations, it will be imperative to conduct future longitudinal studies.

Characterising and differentiating cognitive and motor speed in older adults: structural equation modelling on a UK longitudinal birth cohort

OBJECTIVES

Information processing speed (IPS) has been proposed to be a key component in healthy ageing and cognitive functioning. Yet, current studies lack a consistent definition and specific influential characteristics. This study aimed to investigate IPS as a multifaceted concept by differentiating cognitive and motor IPS.

DESIGN, SETTING AND PARTICIPANTS

A retrospective data analysis using data from the Medical Research Council National Survey of Health and Development (a population-based cohort of UK adults born in 1946) at childhood (ages 8, 11 and 15) and adulthood (ages 60-64 and 68-70). Using structural equation modelling, we constructed two models of IPS with 2124 and 1776 participants, respectively.

OUTCOME MEASURES

Measures of interest included IPS (ie, letter cancellation, simple and choice reaction time), intelligence (ie, childhood intelligence and National Adult Reading Test), verbal memory, socioeconomic status (SES) and cognitive functions measured by the Addenbrooke's Cognitive Examination III, as well as a variety of health indexes.

RESULTS

We found distinct predictors for cognitive and motor IPS and how they relate to other cognitive functions in old age. In our first model, SES and antipsychotic medication usage emerged as significant predictors for cognitive IPS, intelligence and smoking as predictors for motor IPS while both share sex, memory and antiepileptic medication usage as common predictors. Notably, all differences between both IPS types ran in the same direction except for sex differences, with women performing better than men in cognitive IPS and vice versa in motor IPS. The second model showed that both IPS measures, as well as intelligence, memory, antipsychotic and sedative medication usage, explain cognitive functions later in life.

CONCLUSION

Taken together, these results shed further light on IPS as a whole by showing there are distinct types and that these measures directly relate to other cognitive functions.

Smoking affects the association between cognitive impairment and P50 inhibition defects in patients with chronic schizophrenia: A case-control study

OBJECTIVE

Smoking affects sensory gating, as assessed by the event related potential P50, which is evoked by auditory stimuli and is considered to be involved in the pathophysiology of schizophrenia (SCZ). However, few studies have compared sensory gating and cognitive performance between smoking and non-smoking SCZ patients in the Chinese Han population.

METHODS

We recruited two groups of Chinese subjects: 128 male chronic SCZ patients and 76 male healthy controls, measuring cognition with the MATRICS Consensus Cognitive Battery (MCCB) and sensory gating with the P50 EEG components. Based on their smoking status, they were further divided into 4 subgroups: smoking SCZ patients, non-smoking SCZ patients, smoking healthy controls, and non-smoking healthy controls. We assessed psychopathological symptoms of the patients using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Compared with healthy controls, SCZ patients had lower MCCB total score and scores of all 10 tests (all p < 0.05), while SCZ patients had higher S2 amplitudes and P50 ratios (both p < 0.05). When comparing smoking versus non-smoking SCZ patients, non-smokers had significantly better spatial span (p < 0.05). Furthermore, the S1 amplitude was negatively correlated with the Brief Visuospatial Memory Test (BVMT-R) in smoking patients (p < 0.05), while the S1 latency was negatively correlated with spatial span in non-smoking patients (p < 0.01).

CONCLUSIONS

Our finding shows a difference in the relationship between sensory gated P50 and cognition in smoking and non-smoking SCZ patients, suggesting that nicotine may improve cognitive and P50 deficits in SCZ patients.

Relationship between urinary dichlorophenols and cognitive function among people over 60 years old from NHANES

Studies have shown that exposure to dichlorophenols (DCPs) and their precursors might have potential neurotoxicity, which may be related to low cognitive function, but there are few large-scale, representative population data to explore the association between DCP exposure and cognitive function. We aimed to examine the relationship between urinary DCPs and cognitive function in the US older people. A total of 952 participants ≥ 60 years old from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2011-2014) were enrolled. The Consortium to Establish a Registry for Alzheimer's disease Word Learning subtest (CERAD W-L), the Animal Fluency test (AFT), and the Digit Symbol Substitution test (DSST) were used to assess cognition. Multivariate logistic regression and restricted cubic spline (RCS) were used to evaluate the relationship between DCP exposure and cognitive function. A positive association between 2,5-DCP and the risk of bad performance of DSST was observed (P for trend = 0.024) after adjusting for the covariates. Compared to the lowest quartile, OR of DSST for the highest quartile of 2,5-DCP was 1.72 (95%CI:1.03-2.87, P = 0.039). There were no significant associations between DCPs and the other tests. The RCS plot showed an inverted J-shaped relationship between 2,5-DCP, 2,4-DCP, and the DSST score. The inflection points for the curves were found at 1.531 μg/L and 0.230 μg/L, respectively. On the right side of the inflection points, the DSST score dropped sharply. In subgroup analysis, those under 70 years old, smokers, and alcohol drinkers had a higher risk of bad performance in DSST when exposed to 2,5-DCP. The higher concentration of urinary DCPs is associated with a lower score of DSST in the US older people.

The Differential Effects of Chronic Alcohol and Cigarette Smoke Exposures on Cognitive-Behavioral Dysfunction in Long Evans Rats

Background and Objective

Chronic heavy alcohol consumption and daily cigarette smoking are the most prevalent substance use problems in the U.S., including Veterans. Excessive alcohol use causes neurocognitive and behavioral deficits that can be linked to neurodegeneration. Similarly, preclinical and clinical data suggest that smoking also leads to brain atrophy. This study examines the differential and additive effects of alcohol and cigarette smoke (CS) exposures on cognitive-behavioral function.

Methods

A 4-way experimental model of chronic alcohol and CS exposures was generated using 4-week-old male and female Long Evans rats that were pair-fed with Lieber-deCarli isocaloric liquid diets containing 0% or 24% ethanol for 9 weeks. Half of the rats in the control and ethanol groups were exposed to CS for 4 hours/day and 4 days/week for 9 weeks. All rats were subjected to Morris Water Maze, Open Field, and Novel Object Recognition testing in the last experimental week.

Results

Chronic alcohol exposure impaired spatial learning as shown by significantly increased latency to locate the platform, and it caused anxiety-like behavior marked by the significantly reduced percentage of entries to the center of the arena. Chronic CS exposure impaired recognition memory as suggested by significantly less time spent at the novel object. Combined exposures to alcohol and CS did not show any significant additive or interactive effect on cognitive-behavioral function.

Conclusion

Chronic alcohol exposure was the main driver of spatial learning, while the effect of secondhand CS exposure was not robust. Future studies need to mimic direct CS exposure effects in humans.

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.

Vascular Cognitive Impairment (VCI)

Vascular cognitive impairment (VCI) is predominately caused by vascular risk factors and cerebrovascular disease. VCI includes a broad spectrum of cognitive disorders, from mild cognitive impairment to vascular dementia caused by ischemic or hemorrhagic stroke, and vascular factors alone or in a combination with neurodegeneration including Alzheimer's disease (AD) and AD-related dementia. VCI accounts for at least 20-40% of all dementia diagnosis. Growing evidence indicates that cerebrovascular pathology is the most important contributor to dementia, with additive or synergistic interactions with neurodegenerative pathology. The most common underlying mechanism of VCI is chronic age-related dysregulation of CBF, although other factors such as inflammation and cardiovascular dysfunction play a role. Vascular risk factors are prevalent in VCI and if measured in midlife they predict cognitive impairment and dementia in later life. Particularly, hypertension, high cholesterol, diabetes, and smoking at midlife are each associated with a 20 to 40% increased risk of dementia. Control of these risk factors including multimodality strategies with an inclusion of lifestyle modification is the most promising strategy for treatment and prevention of VCI. In this review, we present recent developments in age-related VCI, its mechanisms, diagnostic criteria, neuroimaging correlates, vascular risk determinants, and current intervention strategies for prevention and treatment of VCI. We have also summarized the most recent and relevant literature in the field of VCI.

Sex differences in P50 inhibition defects with psychopathology and cognition in patients with first-episode schizophrenia

BACKGROUND

A large number of studies have shown that the pathophysiology of schizophrenia may be involved in sensory gating that appears to be P50 inhibition. However, few studies have investigated the relationship between clinical symptoms, cognitive impairment and sensory gating disorders in patients with first-episode schizophrenia. The purpose of this study was to explore the sex differences in the relationship between clinical symptoms, cognitive impairment and P50 inhibition defects in patients with first-episode schizophrenia, which has not been reported.

METHODS

130 patients with first-episode schizophrenia (53 males and 77 females) and 189 healthy controls (87 males and 102 females) participated in the study. Positive and Negative Syndrome Scale (PANSS) was used to evaluate the patients' psychopathological symptoms, and the 64-channel electroencephalogram (EEG) system was used to record the P50 inhibition.

RESULTS

Male patients had higher PANSS negative symptom, general psychopathology, cognitive factor and total scores than female patients (all p < 0.01). The S1 amplitude was smaller in male than female patients (all p < 0.05). Multiple regression analysis showed that in male patients, S1 latency was contributor to negative symptoms, while S1 latency, S2 latency, age, and smoking status were contributors to cognitive factor (all p < 0.05). In female patients, no P50 component was found to be an independent contributor to PANSS scores (all p > 0.05).

CONCLUSIONS

Our results indicate that there is a sex difference in the relationship between clinical symptoms, cognitive impairment and P50 inhibition defects in Chinese Han patients with first-episode schizophrenia.

The negative impact of chronic tobacco smoking on adult neuropsychological function: a cross-sectional study

Background

The evidence on the effects of chronic tobacco smoking on neuropsychological functions is conflicting. The literature remains limited by inconsistent accounting for potentially confounding biomedical and psychiatric conditions. This study aimed to assess the neuropsychological functions of adult chronic tobacco smokers in comparison to group-matched non-smokers.

Method

The study included 73 smokers and 84 group-matched non-smokers. The data was collected during the year 2019. After an initial interview to collect demographics and smoking profile, the subjects undertook neuropsychological assessments that targeted a wide range of cognitive domains.

Results

The performance of smokers was poorer on almost all neuropsychological domains, namely selective attention (p ≤ .001, p = .044), alternating attention (p = .002) working memory (p ≤ .001), Short-term memory (p = .006 and .003), Long-term memory (p ≤ .001), processing accuracy (p ≤ .001), and executive function (p = .011 and .026). Smokers were intact on processing speed. Smoking accumulation and lower age onset of regular smoking were correlated with lower neuropsychological function.

Conclusion

Our findings add to the growing body of evidence suggesting that chronic tobacco smoking impacts cognition negatively.

Systematic Review of Pulmonary Function and Cognition in Aging

BACKGROUND

Substantial research is dedicated to understanding the aging-related dynamics among individual differences in level, change, and variation across physical and cognitive abilities. Evaluating replicability and synthesizing findings has been limited by differences in measurements, samples, study design, and statistical analyses that confound between-person differences with within-person changes. Here, we systematically reviewed longitudinal results on the aging-related dynamics linking pulmonary function and cognitive performance.

METHODS

Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines were used to systematically review longitudinal studies of pulmonary function and cognition.

RESULTS

Only four studies thoroughly investigating cognitive and pulmonary longitudinal associations (three or more measurement occasions) were identified. Expanded review criteria identified three studies reporting two measurement occasions, and seven studies reporting one measurement of pulmonary function or cognition and two or more measurements of the other. We identified numerous methodological quality and risk for bias issues across studies.

CONCLUSIONS

Despite documented correlational associations between pulmonary function and cognition, these results show there is very limited research thoroughly investigating their longitudinal associations. This highlights the need for longitudinal data, rigorous methodological design including key covariates, and clear communication of methods and analyses to facilitate replication across an array of samples. We recommend systematic study of outcome measures and covariates, inclusion of multiple measures (e.g., peak expiratory flow, forced expiratory volume in 1 s, and forced vital capacity), as well as application of the same analytic approach across multiple datasets.

Carotid Artery Stiffness is Associated With Cognitive Performance in Former Smokers With and Without Chronic Obstructive Pulmonary Disease

Background Heavy smokers perform worse on neuropsychological assessment than age-matched peers. However, traditional pulmonary measures of airflow limitation and hypoxemia explain only a modest amount of variance in cognition. The current objective was to determine whether carotid artery stiffness is associated with cognition in former smokers beyond the effects of amount of smoking and pulmonary function. Methods and Results Eighty-four former smokers including individuals across a spectrum of airflow limitation severity were included: 30 without chronic obstructive pulmonary disease (Global Initiative for Chronic Obstructive Lung Disease [GOLD] 0 with normal spirometry and lung computed tomography), 31 with mild-moderate chronic obstructive pulmonary disease (GOLD 1-2), and 23 with severe-very severe chronic obstructive pulmonary disease (GOLD 3-4). Participants completed questionnaires, spirometry, carotid ultrasonography, and neuropsychological testing. Multiple linear regression was used to determine whether carotid artery stiffness is associated with neuropsychological performance in 4 cognitive domains after adjusting for age, sex, pack-years of smoking, estimated premorbid intellectual functioning, and airflow limitation. Higher carotid artery β-stiffness index was associated with reduced executive functioning-processing speed in the fully adjusted model (β=-0.49, SE=0.14; P=0.001). Lower premorbid intellectual function, male sex, and presence of airflow limitation (GOLD 1 or 2 and GOLD 3 or 4) were also associated with worse executive functioning-processing speed. β-Stiffness index was not significantly associated with performance in other cognitive domains. Conclusions Carotid artery stiffness is associated with worse performance on executive functioning-processing speed in former smokers beyond the effects of aging, amount of past smoking, severity of airflow limitation, and hypoxemia. Future research should examine whether carotid stiffness can be used to identify former smokers at risk for subsequent cognitive impairment.

Short-term E-cigarette toxicity effects on brain cognitive memory functions and inflammatory responses in mice

Exposure to cigarette smoke (CS) is associated with an increased risk of several neurological diseases such as stroke, Alzheimer's disease, and dementia. At present, commercialization of E-cigarettes (ECs) is increasing, and they are advertised as a less harmful nicotine-delivery system. There are, however, limited studies regarding the neurotoxicity effects of ECs on the brain, which remains a subject of debate. In the present study, we aimed to evaluate the in vivo effects of short-term EC vapor exposure on the brain and compare them with the effects of cigarette smoke (CS). BALB/c mice were exposed to air, CS, and EC for 14 days. We then assessed the inflammatory responses, oxidative stress, and cognitive functions of the mice by using maze tests. Cognitive spatial tests showed that the mice exposed to CS and ECs had delayed time in finding food rewards. EC exposure demonstrated no improvement in spatial memory learning to find the food reward on the next day. This implies that CS and EC exposure possibly causes damage to the olfactory system. Notably, EC exposure potentially causes abnormalities in mice memory functions. Histological staining of the cerebral cortex of mice brain in the EC-exposed group demonstrated inflammatory responses such as necrosis and cytoplasm vacuolization. Immunohistochemical staining revealed high expression of proinflammatory cytokine TNF-α in both the EC- and CS-exposed groups. Hence, we conclude that ECs share similar toxicity profiles as CS, which potentially negatively impact brain function.

Tobacco Use and Cognitive Functioning in Veterans of the Conflicts in Iraq and Afghanistan

Tobacco use is a prevalent problem in the general population as well as among military veterans. Despite the fact that tobacco users are at an increased risk of many medical and psychiatric comorbidities, the risk of cognitive impairment in younger active tobacco users is less studied. Military veterans from the conflicts in Iraq and Afghanistan (n = 113) were administered a neuropsychological protocol. Even after controlling for the severity of PTSD symptoms, tobacco use was negatively related to performance on measures of processing speed, memory, and executive functioning. The current findings have implications for the neuropsychological evaluation of tobacco users.

Effects of smoking on cognition and BDNF levels in a male Chinese population: relationship with BDNF Val66Met polymorphism

Recent studies demonstrate that brain-derived neurotrophic factor (BDNF) might be associated with nicotine addiction, and circulating BDNF is a biomarker of memory and general cognitive function. Moreover, studies suggest that a functional polymorphism of the BDNF Val66Met may mediate hippocampal-dependent cognitive functions. We aimed to explore the relationships between smoking, cognitive performance and BDNF in a normal Chinese Han population. We recruited 628 male healthy subjects, inducing 322 smokers and 306 nonsmokers, and genotyped them the BDNF Val66Met polymorphism. Of these, we assessed 114 smokers and 98 nonsmokers on the repeatable battery for the assessment of neuropsychological status (RBANS), and 103 smokers and 89 nonsmokers on serum BDNF levels. Smokers scored lower than the nonsmokers on RBANS total score (p = 0.002), immediate memory (p = 0.003) and delayed memory (p = 0.021). BDNF levels among the smokers who were Val allele carriers were correlated with the degree of cognitive impairments, especially attention, as well as with the carbon monoxide concentrations. Our findings suggest that smoking is associated with cognitive impairment in a male Chinese Han population. The association between higher BDNF levels and cognitive impairment, mainly attention in smokers appears to be dependent on the BDNF Val66Met polymorphism.

Healthy cognitive ageing in the Lothian Birth Cohort studies: marginal gains not magic bullet

In the face of shifting demographics and an increase in human longevity, it is important to examine carefully what is known about cognitive ageing, and to identify and promote possibly malleable lifestyle and health-related factors that might mitigate age-associated cognitive decline. The Lothian Birth Cohorts of 1921 (LBC1921, n = 550) and 1936 (LBC1936, n = 1091) are longitudinal studies of cognitive and brain ageing based in Scotland. Childhood IQ data are available for these participants, who were recruited in later life and then followed up regularly. This overview summarises some of the main LBC findings to date, illustrating the possible genetic and environmental contributions to cognitive function (level and change) and brain imaging biomarkers in later life. Key associations include genetic variation, health and fitness, psychosocial and lifestyle factors, and aspects of the brain's structure. It addresses some key methodological issues such as confounding by early-life intelligence and social factors and emphasises areas requiring further investigation. Overall, the findings that have emerged from the LBC studies highlight that there are multiple correlates of cognitive ability level in later life, many of which have small effects, that there are as yet few reliable predictors of cognitive change, and that not all of the correlates have independent additive associations. The concept of marginal gains, whereby there might be a cumulative effect of small incremental improvements across a wide range of lifestyle and health-related factors, may offer a useful way to think about and promote a multivariate recipe for healthy cognitive and brain ageing.

Executive function fails to predict smoking outcomes in a clinical trial to motivate smokers to quit

BACKGROUND

Executive function (EF) is considered an important mediator of health outcomes. It is hypothesized that those with better EF are more likely to succeed in turning their intentions into actual health behaviors. Prior studies indicate EF is associated with smoking cessation. Experimental and longitudinal studies, however, have yielded mixed results. Few studies have examined whether EF predicts post-treatment smoking behavior. Fewer still have done so prospectively in a large trial. We sought to determine if EF predicts quit attempts and cessation among community smokers in a large randomized trial evaluating the efficacy of motivational interventions for encouraging cessation.

METHODS

Participants (N=255) completed a baseline assessment that included a cognitive battery to assess EF (Oral Trail Making Test B, Stroop, Controlled Oral Word Association Test). Participants were then randomized to 4 sessions of Motivational Interviewing or Health Education or one session of Brief Advice to quit. Quit attempts and cessation were assessed at weeks 12 and 26.

RESULTS

In regression analyses, none of the EF measures were statistically significant predictors of quit attempts or cessation (all ps>0.20).

CONCLUSIONS

Our data did not support models of health behavior that emphasize EF as a mediator of health outcomes. Methodological shortcomings weaken the existing support for an association between EF and smoking behavior. We suggest methodological improvements that could help move this potentially important area of research forward.

Prospective Analysis of the Influence of Sport and Educational Factors on the Prevalence and Initiation of Smoking in Older Adolescents from Croatia

The prevalence of smoking among Croatian adolescents is alarmingly high, but no previous study has prospectively examined the sport- and academic-factors associated with smoking and smoking initiation. This study aimed to prospectively examine the associations between scholastic (educational) achievement and sport factors and smoking in 16- to 18-year-old adolescents. This two-year prospective cohort study included 644 adolescents who were 16 years of age at baseline (46% females). Baseline testing was implemented at the beginning of the 3rd year of high school (September 2014) when participants were 16 years old. Follow-up testing was completed at the end of the fourth year of high school, which occurred 20 months later. The evaluated predictor variables were educational-achievement- and sport-related-factors. The outcome variables were (i) smoking at baseline; (ii) smoking at follow-up; and (iii) smoking initiation over the course of the study. We assessed the associations between predictors and outcomes using logistic regression models adjusted for age, gender, socioeconomic status, and conflict with parents. The educational variables were consistently associated with smoking, with lower grade-point-average (Baseline: odd ratio (OR): 2.01, 95% confidence interval (CI): 1.61–2.55; Follow-up: 1.59, 1.31–1.94), more frequent absence from school (Baseline: OR: 1.40, 95% CI: 1.19–1.69; Follow-up: 1.30, 1.08–1.58), and lower behavioral grades (Baseline: OR: 1.80, 95% CI: 1.10–2.89; Follow-up: 1.57, 1.03–2.41) in children who smoke. Adolescents who reported quitting sports were at greater odds of being smokers (Baseline: 2.07, 1.31–3.32; Follow-up: 1.66, 1.09–2.56). Sport competitive achievement at baseline was protective against smoking initiation during following two-year period (0.45, 0.21–0.91). While the influence of the educational variables on smoking initiation has been found to be established earlier; sport achievement was identified as a significant protective factor against initiating smoking in older adolescents. Results should be used in development of an anti-smoking preventive campaign in older adolescents.

Decreased Central Nervous System Grey Matter Volume (GMV) in Smokers Affects Cognitive Abilities: A Systematic Review

Although cigarette smoking is a leading cause of preventable mortality, tobacco is consumed by approximately 22% of the adult population worldwide. Smoking is also a risk factor for cardiovascular disease, affects brain processing, and is a recognized risk factor for Alzheimer disease (AD). Tobacco toxins (e.g., nicotine at high levels) inhaled in smoke may cause disorders resulting in preclinical brain changes. Researchers suggest that there are differences in brain volume between smokers and non-smokers. This review examines these differences in brain grey matter volume (GMV). In March/April 2015, MedLine, Embase, and PsycINFO were searched using the terms: "grey matter" AND "voxel-based" AND "smoking" AND "cigarette". The 4 studies analyzed found brain GMV decreases in smokers compared to non-smokers. Furthermore, sex-specific differences were found; while the thalamus and cerebellum were affected in both sexes, decreased GMV in the olfactory gyrus was found only in male smokers. Age-group differences were also found, and these may suggest pre-existing abnormalities that lead to nicotine dependence in younger individuals. Only 1 study found a positive correlation between number of pack-years smoked and GMV. Smoking decreases GMV in most brain areas. This decrease may be responsible for the cognitive impairment and difficulties with emotional regulation found in smokers compared with non-smokers.

Sport and scholastic factors in relation to smoking and smoking initiation in older adolescents: a prospective cohort study in Bosnia and Herzegovina

OBJECTIVE

Sport and scholastic factors are known to be associated with cigarette smoking in adolescence, but little is known about the causality of this association. The aim of this study was to prospectively explore the relationships of different sport and scholastic factors with smoking prevalence initiation in older adolescents from Bosnia and Herzegovina.

METHODS

In this 2-year prospective cohort study, there were 872 adolescent participants (16 years at baseline; 46% females). The study consisted of baseline tests at the beginning of the third year (September 2013) and follow-up at the end of the fourth year of high school (late May to early June 2015). The independent variables were scholastic and sport-related factors. The dependent variables were (1) smoking at baseline, (2) smoking at follow-up and (3) smoking initiation over the course of the study. Logistic regressions controlling for age, gender and socioeconomic status were applied to define the relationships between independent and dependent variables.

RESULTS

School absence at the baseline study was a significant predictor of smoking initiation during the course of the study (OR 1.4, 95% CI 1.1 to 1.8). Those who reported quitting sports at baseline showed an increased risk of smoking at the end of the study (OR 1.4, 95% CI 1.1 to 2.0) and of smoking initiation (OR 1.8, 95% CI 1.3 to 2.0). Adolescents who reported lower competitive achievements in sport were at a higher risk of (1) smoking at baseline (OR 1.5, 95% CI 1.1 to 2.1), (2) smoking at follow-up (OR 1.5, 95% CI 1.1 to 2.1) and (3) smoking initiation (OR 1.6, 95% CI 1.1 to 2.6).

CONCLUSIONS

In developing accurate antismoking public health policies for older adolescents, the most vulnerable groups should be targeted. The results showed that most participants initiated smoking before 16 years of age. Therefore, further investigations should evaluate the predictors of smoking in younger ages.

Developmental toxicity of nicotine: A transdisciplinary synthesis and implications for emerging tobacco products

While the health risks associated with adult cigarette smoking have been well described, effects of nicotine exposure during periods of developmental vulnerability are often overlooked. Using MEDLINE and PubMed literature searches, books, reports and expert opinion, a transdisciplinary group of scientists reviewed human and animal research on the health effects of exposure to nicotine during pregnancy and adolescence. A synthesis of this research supports that nicotine contributes critically to adverse effects of gestational tobacco exposure, including reduced pulmonary function, auditory processing defects, impaired infant cardiorespiratory function, and may contribute to cognitive and behavioral deficits in later life. Nicotine exposure during adolescence is associated with deficits in working memory, attention, and auditory processing, as well as increased impulsivity and anxiety. Finally, recent animal studies suggest that nicotine has a priming effect that increases addiction liability for other drugs. The evidence that nicotine adversely affects fetal and adolescent development is sufficient to warrant public health measures to protect pregnant women, children, and adolescents from nicotine exposure.

Cigarette smoke and related risk factors in neurological disorders: An update

Cigarette smoking is known to be harmful to health, and is considered the main cause of death worldwide, especially in India. Among the well-distinguished diseases related to smoking are, chronic obstructive pulmonary disease, oral and peripheral cancers, and cardiovascular complications. However, the impact of cigarette smoking on neurocognitive and neuropathological effects, including anxiety, Alzheimer's disease, Parkinson's disease, ischemic stroke, and blood-brain barrier dysfunction, still remains unclear. Cigarette smoke consists of more than 4500 toxic chemicals that combine to form free radicals, which lead to oxidative stress-associated neurological disorders. Herein, we discuss the role of antioxidant agents in delaying or attenuating disease complications. In addition, in this review, we discuss the neuropathological effect of cigarette smoke and its interference in neurodegeneration.

Neural Mechanisms and Children’s Intellectual Development

Human psychometric intelligence can predict a number of important social and academic outcomes. Substantial parts of the variances of human intelligence and the brain volume supporting those abilities are explained by environmental factors, and during childhood, human brains have higher plasticity and also 60% of variance of intelligence that is explained by environmental factors. Here, we review the representative environmental factors known to affect human intellectual development during each developmental stage. We describe what is (and what is not) being investigated to determine how these factors affect human brain development through analyses of volumetrical and cortical structures. In conclusion, environmental factors that affect children’s intellectual development lead to three patterns of brain structural change. The first is global change in the brain structure, observed more often in the earlier phase of development. The second is structural changes concentrated in the medial prefrontal and adjacent areas and medial temporal areas, which are likely to be induced by stress in many cases. The third is sporadic region-specific change, likely to be primarily caused by use-dependent plasticity of the areas that is often observed in the later phase of development. These changes may underlie the alterations in children’s intellectual development that is induced by environmental factors.

A Lack of Correlation between Brain-Derived Neurotrophic Factor Serum Level and Verbal Memory Performance in Healthy Polish Population

Brain derived neurotrophic factor (BDNF) is considered to be connected with memory and learning through the processes of long term synaptic potentiation and synaptic plasticity. The aim of the study was to examine the relationship between precursor BDNF (proBNDF) and mature BDNF (mBDNF) serum levels and performance on Rey Auditory-Verbal Learning Test (RAVLT) in 150 healthy volunteers. In addition, we have verified the relationships between serum concentration of both forms of BDNF and RAVLT with sociodemographic and lifestyle factors.We found no strong evidence for the correlation of proBDNF and mBDNF serum levels with performance on RAVLT in healthy Polish population in early and middle adulthood. We observed the mBDNF serum concentration to be higher in women compared with men. Moreover, we revealed higher mBDNF level to be connected with lower body mass index (BMI). In turn, the results of RAVLT correlated with sociodemographic and lifestyle factors, such as: age, education, gender, BMI and smoking.

Effects of cigarette smoking and alcohol use on neurocognition and BDNF levels in a Chinese population

OBJECTIVE

Few studies have examined the potential interactive effect of both smoking and drinking on cognition. Brain-derived neurotrophic factor (BDNF) plays a critical role in cognition. This is the first study to examine the neurocognitive consequences of cigarette smoking combined with chronic alcohol consumption and their relationship to serum BDNF levels in a Chinese Han population.

MATERIALS AND METHODS

We recruited 191 healthy male subjects, including 47 isolated smokers, 31 isolated chronic alcohol users, 58 combined smokers and chronic alcohol users, and 55 non-smokers and non-alcohol users. We then compared the repeatable battery for the assessment of neuropsychological status (RBANS) scores and serum BDNF levels in these four groups.

RESULTS

When compared to the non-smoking + non-alcohol-using group, the smoking group performed worse on immediate memory, attention, language, and RBANS total score. There were no significant differences in the RBANS scores between the alcohol-using group and non-smoking + non-alcohol-using group, or between the smoking group and smoking + alcohol-using group. We did not find an association between BDNF and smoking or drinking status or between BDNF and cognitive performance. In the smoking group, there was a significant correlation between BDNF and carbon monoxide concentration, and between BDNF and the Fagerstrom Test for Nicotine Dependence (FTND) total score.

CONCLUSIONS

Our results suggest that smoking is associated with cognitive decline, but not with BDNF levels in a normal population. However, smoking severity is positively associated with BDNF levels. Concomitant alcohol use does not worsen the cognitive decline caused by smoking.

Effects of caffeine intake and smoking on neurocognition in schizophrenia

Although most studies support the beneficial effects of caffeine on neurocognition, its effects have never been assessed in psychiatric patients. In addition, results from studies in smokers are contradictory. Moreover, there are no data available about the neurocognitive effects of caffeine and tobacco together. We explored the concomitant effects of regular caffeine and tobacco intake on neurocognition in 52 schizophrenic patients and 61 healthy controls. Verbal fluency, processing speed, and working, visual and verbal memory were assessed. For each measurement, two tasks with two levels of complexity were administered. Our results showed that caffeine intake had beneficial effects on male schizophrenic patients only in complex tasks requiring deeper cognitive processing (semantic fluency, cognitive speed, working memory, and visual memory). Female patients and controls were unaffected. In contrast, smoking had a negative effect on male, but not on female, schizophrenic patients in semantic fluency. The effects of smoking in controls were inconsistent. In conclusion, our data showed, for the first time, beneficial effects of caffeine intake on neurocognition in male schizophrenic patients. These data suggest that further research of therapeutics based on caffeine is needed, as this could be beneficial for schizophrenic patients. In contrast, smoking appears to be detrimental.

Combined effect of obstructive sleep apnea and chronic smoking on cognitive impairment

OBJECTIVES

Little is known about combined effect of obstructive sleep apnea (OSA) and chronic smoking on cognitive impairment. We aimed to determine whether smoking synergizes with OSA in deteriorating cognitive function and whether smoking cessation contributes to cognitive benefits.

METHODS

One hundred and eighteen male patients were enrolled in the study and asked to complete neurocognitive function tests including Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), clock drawing test (CDT), and verbal fluency test (VFT). Variables of those neurocognitive function tests were analyzed with two factors: OSA and smoking.

RESULTS

After adjustment of potential confounding factors, an OSA-by-smoking interaction was found in CDT-C scores and a main smoking effect were showed in MoCA scores. Smoking patients with OSA had the worst performance in the four tests compared with the other three groups (smoking patients without OSA, non-smoking patients with and without OSA). Ex-smokers with OSA tended to perform better than current smokers, but still worse than never-smokers with OSA in those tests.

CONCLUSION

The results suggested that the coexistence of OSA and chronic smoking resulted in more pronounced cognitive deficits than either factor along. Smoking cessation may benefit cognitive function to some extents in patients with OSA.

Gender differences in the effect of tobacco use on brain phosphocreatine levels in methamphetamine-dependent subjects

BACKGROUND

A high prevalence of tobacco smoking has been observed in methamphetamine users, but there have been no in vivo brain neurochemistry studies addressing gender effects of tobacco smoking in methamphetamine users. Methamphetamine addiction is associated with increased risk of depression and anxiety in females. There is increasing evidence that selective analogues of nicotine, a principal active component of tobacco smoking, may ease depression and improve cognitive performance in animals and humans.

OBJECTIVES

To investigate the effects of tobacco smoking and gender on brain phosphocreatine (PCr) levels, a marker of brain energy metabolism reported to be reduced in methamphetamine-dependent subjects.

METHODS

Thirty female and 27 male methamphetamine-dependent subjects were evaluated with phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) to measure PCr levels within the pregenual anterior cingulate, which has been implicated in methamphetamine neurotoxicity.

RESULTS

Analysis of covariance revealed that there were statistically significant slope (PCr versus lifetime amount of tobacco smoking) differences between female and male methamphetamine-dependent subjects (p = 0.03). In females, there was also a statistically significant interaction between lifetime amounts of tobacco smoking and methamphetamine in regard to PCr levels (p = 0.01), which suggests that tobacco smoking may have a more significant positive impact on brain PCr levels in heavy, as opposed to light to moderate, methamphetamine-dependent females.

CONCLUSION

These results indicate that tobacco smoking has gender-specific effects in terms of increased anterior cingulate high energy PCr levels in methamphetamine-dependent subjects. Cigarette smoking in methamphetamine-dependent women, particularly those with heavy methamphetamine use, may have a potentially protective effect upon neuronal metabolism.

Reduced executive and default network functional connectivity in cigarette smokers

Altered functional connectivity has been associated with acute and chronic nicotine use. Connectivity alterations, specifically in the right and left executive control networks (RECN/LECN) and the default mode network (DMN), may contribute to the addiction cycle. The objective of this study was to determine if executive control network (ECN) and DMN connectivity is different between non-smokers and smokers and whether reductions in connectivity are related to chronic cigarette use. The RECN, LECN, and DMN were identified in resting state functional magnetic resonance imaging data in 650 subjects. Analyses tested for group differences in network connectivity strength, controlling for age and alcohol use. There was a significant group effect on LECN and DMN connectivity strength with smokers (n = 452) having lower network strengths than non-smokers (n = 198). Smokers had lower connectivity than non-smokers associated with key network hubs: the dorsolateral prefrontal cortex, and parietal nodes within ECNs. Further, ECN connectivity strength was negatively associated with pack years of cigarette use. Our data suggest that chronic nicotine use negatively impacts functional connectivity within control networks that may contribute to the difficulty smokers have in quitting.

Sex-related and tissue-specific effects of tobacco smoking on brain atrophy: assessment in a large longitudinal cohort of healthy elderly

We investigated the cross-sectional and longitudinal effects of tobacco smoking on brain atrophy in a large cohort of healthy elderly participants (65–80 years). MRI was used for measuring whole brain (WB), gray matter (GM), white matter (WM), and hippocampus (HIP) volumes at study entry time (baseline, N = 1451), and the annualized rates of variation of these volumes using a 4-year follow-up MRI in a subpart of the cohort (N = 1111). Effects of smoking status (never, former, or current smoker) at study entry and of lifetime tobacco consumption on these brain phenotypes were studied using sex-stratified AN(C)OVAs, including other health parameters as covariates. At baseline, male current smokers had lower GM, while female current smokers had lower WM. In addition, female former smokers exhibited reduced baseline HIP, the reduction being correlated with lifetime tobacco consumption. Longitudinal analyses demonstrated that current smokers, whether men or women, had larger annualized rates of HIP atrophy, as compared to either non or former smokers, independent of their lifetime consumption of tobacco. There was no effect of smoking on the annualized rate of WM loss. In all cases, measured sizes of these tobacco-smoking effects were of the same order of magnitude than those of age, and larger than effect sizes of any other covariate. These results demonstrate that tobacco smoking is a major factor of brain aging, with sex- and tissue specific effects, notably on the HIP annualized rate of atrophy after the age of 65.

Smoking, MATRICS consensus cognitive battery and P50 sensory gating in a Han Chinese population

BACKGROUND

The effects of smoking on cognitive performance have long been studied, with mixed results. P50 sensory gating has been used as endophenotype for studying nicotinic systems genetics, and P50 gating deficits have been reported to be a sensitive biomarker for cognitive impairment in schizophrenia. This study examined the inter-relationship between P50 suppression, cognitive function, and smoking in a healthy Han Chinese population, which has not been reported before.

METHODS

We recruited 82 healthy male subjects, including 48 smokers and 34 non-smokers who were matched for age and education. The authors measured P50 sensory gating and administered the Chinese-language version of the MATRICS consensus cognitive battery (MCCB) and Stroop tests.

RESULTS

The results showed that the smokers scored lower than nonsmokers on the MCCB brief visuospatial memory test (BVMT) index and the STROOP test. Furthermore, the MCCB total score was negatively associated with number of cigarettes smoked per day in the smoker group. However, P50 sensory gating was not associated with either smoking status or any cognitive performance.

CONCLUSIONS

Our results show that smoking is associated with cognitive impairment, but not with P50 sensory gating.

Concurrent use of khat and tobacco is associated with verbal learning and delayed recall deficits

AIMS

The present study assessed whether cigarette smokers who are also regular khat users would demonstrate greater impairments in verbal learning and recall compared to both non-smokers who are khat users and control subjects.

DESIGN

An independent-measures, between-subjects design with two covariates.

SETTING

An out-patient, university research center in Taiz, Yemen.

PARTICIPANTS

Subjects were 175 Yemeni college students (90 men, 85 women) ranging in age from 18 to 38 years. Seventy-five subjects were self-reported chronic cigarette smokers and khat users, 48 non-smoking subjects were self-reported to be chronic khat users and 52 non-smoking subjects reported no current use or history of khat use.

MEASUREMENTS

Verbal learning and verbal memory recall was assessed by subject performance on the Arabic version of the Rey Auditory Verbal Learning Test (RAVLT).

FINDINGS

Statistically significant differences (P < 0.05) were observed in RAVLT acquisition learning trials 2-5 and on delayed recall measures between concurrent khat and cigarette users compared to both the khat-only group and the control group of non-users of khat and cigarettes. On each of these trials, concurrent users recalled fewer words, demonstrating a slowed rate of verbal learning. This same pattern of performance was also seen on delayed recall measures. Khat use alone did not affect immediate or delayed recall of previously learned words.

CONCLUSIONS

Khat users who smoke cigarettes have a lower rate of verbal learning and delayed recall of previously learned verbal material than khat users who do not smoke cigarettes. This may be due to pre-existing differences between these groups of subjects.

Poor working memory and reduced blood pressure levels in concurrent users of khat and tobacco

INTRODUCTION

The purpose of this study was to examine the extent in which concurrent use of khat and tobacco was associated with decrements in working memory. We also tested whether cardiovascular activity during a cognitive task was related to performance outcomes, as research has shown linkages between maladaptive physiological adjustments and cognitive functions.

METHODS

Seventy-four concurrent users of khat and tobacco, 49 khat-only users, and 52 nonusers (M age ± SD: 23.8±4.8) completed a laboratory session including 10 min of a mental arithmetic challenge task. Systolic blood pressure (SBP) and diastolic blood pressure and heart rate were collected throughout the task. Analyses of variance and correlational analyses were conducted.

RESULTS

We found that concurrent users evidenced the lowest number of correct responses on the math task among these 3 groups (ps < .05). Concurrent users also showed fewer number of attempts than khat-only users (ps < .01) and lower accuracy rate than nonusers (ps < .05). The performance of khat-only users and nonusers were comparable on these 3 measures (p > .76). Overall blood pressure levels were lower in concurrent users than in nonusers (p < .05). Correlational analysis found that lower SBP during the math task was associated with fewer number of correct responses and attempts and lower accuracy rate on the task (ps < .05). Multiple regression analysis controlling for gender found that concurrent use predicted math performance (ps < .05). Reported duration and frequency of khat and tobacco use and nicotine dependence predicted performance measures (ps < .05).

CONCLUSIONS

These findings suggest potential linkages between concurrent use of khat and tobacco and impaired working memory.

The effects of chronic cigarette smoking on cognitive recovery during early abstinence from alcohol

BACKGROUND

Alcohol use disorders are related to neurocognitive abnormalities during early abstinence in those seeking treatment for alcohol dependence (ALC). Considerable evidence indicates that chronic cigarette smoking is associated with multiple neurocognitive deficiencies. However, very little is known about the effects of chronic smoking on neurocognitive recovery during early abstinence from alcohol. We evaluated whether cigarette smoking interferes with cognitive improvement during early abstinence from alcohol, a period thought important for maintaining long-term sobriety.

METHODS

Neurocognitive functions previously shown to be adversely affected by both alcohol use disorders and chronic cigarette smoking were evaluated. We assessed 35 smoking ALC (sALC) and 34 nonsmoking ALC (nsALC) at approximately 1 and 5 weeks of monitored abstinence.

RESULTS

Although neither group was clinically impaired, both cross-sectional and longitudinal deficiencies were observed in sALC versus nsALC in processing speed, working memory, and auditory-verbal learning and memory. Lifetime alcohol consumption, medical, and psychiatric comorbidities did not predict neurocognitive performance or improvement across assessments. Within sALC, greater drinking and smoking severities were synergistically (more than additively) related to less improvement on visuospatial learning and memory. Former smoking status in the nsALC-mediated group differences in auditory-verbal delayed recall.

CONCLUSIONS

Chronic cigarette smoking appears to negatively impact neurocognition during early abstinence from alcohol. Although the cognitive deficiencies observed in this cohort were not in a clinical range of impairment, they should be considered to enhance treatment efficacy. Our findings lend support to integrating smoking cessation as well as the individual assessment of cognition into early ALC treatment. Additionally, there is a need to elucidate the effects of current and former smoking status in future reports of neurocognition.

Brain volumes and neuropsychological performance are related to current smoking and alcoholism history

BACKGROUND

Dual dependence on alcohol and nicotine is common, with many reports suggesting that more than 80% of alcoholics also smoke cigarettes. Even after cessation of alcohol consumption, many recovering alcoholics continue to smoke. In this exploratory study, we examined how current smoking and a history of alcoholism interacted in relation to brain volumes and neuropsychological performance.

METHODS

Participants were 14 abstinent long-term alcoholics (seven current smokers and seven nonsmokers), and 13 nonalcoholics (six current smokers and seven nonsmokers). The groups were equivalent in age, gender, education, and intelligence quotient. Two multiecho magnetization-prepared rapid acquisition with gradient echo (MP-RAGE) scans were collected for all participants using a 3T magnetic resonance imaging scanner with a 32 channel head coil. Brain volumes for each gray and white matter region of interest were derived using FreeSurfer. Participants completed a battery of neuropsychological tests measuring intelligence quotient, memory, executive functions, personality variables, and affect.

RESULTS

COMPARED TO NONSMOKING NONALCOHOLICS, ALCOHOLICS WHO SMOKE (THE COMORBID GROUP) HAD VOLUMETRIC ABNORMALITIES IN: pre- and para-central frontal cortical areas and rostral middle frontal white matter; parahippocampal and temporal pole regions; the amygdala; the pallidum; the ventral diencephalic region; and the lateral ventricle. The comorbid group performed worse than nonsmoking nonalcoholics on tests of executive functioning and on visually-based memory tests. History of alcoholism was associated with higher neuroticism scores among smokers, and current smoking was associated with higher sensation seeking scores and lower extraversion scores among nonalcoholics.

CONCLUSION

Results from this exploratory study support and extend prior reports showing that alcoholism and smoking, alone and in combination, are associated with structural brain abnormalities and poorer performance on neuropsychological tests. Therefore, it is important to consider smoking status in alcoholism studies and vice versa.

The role of lifestyle behaviors on 20-year cognitive decline

This study examined the association between smoking, physical activity and dietary choice at 36 and 43 years, and change in these lifestyle behaviors between these ages, and decline in verbal memory and visual search speed between 43 and 60-64 years in 1018 participants from MRC National Survey of Health and Development (NSHD, the British 1946 birth cohort). ANCOVA models were adjusted for sex, social class of origin, childhood cognition, educational attainment, adult social class, and depression; then the lifestyle behaviors were additionally mutually adjusted. Results showed that healthy dietary choice and physical activity were associated, respectively, with slower memory and visual search speed decline over 20 years, with evidence that increasing physical activity was important. Adopting positive health behaviors from early midlife may be beneficial in reducing the rate of cognitive decline and ultimately reducing the risk of dementia.

Smoking, childhood IQ, and cognitive function in old age

OBJECTIVES

To examine the association between smoking history and cognitive function in old age, and whether it remains after controlling for childhood cognitive ability (IQ) and adult socioeconomic status (SES).

METHODS

In the Lothian Birth Cohort 1936 Study, 1080 men and women, who previously participated in a nationwide IQ-type test in childhood, were followed up at age 70. The associations between smoking history and age 70 IQ, general cognitive ability (g), processing speed, memory, and verbal ability were assessed.

RESULTS

Lower childhood IQ was associated with a higher risk of becoming a smoker and continuing to smoke in late life, and with reduced lung function (FEV1) in late life. Current smokers scored significantly lower than ex-smokers and never smokers on tests of age 70 IQ, general cognitive ability, and processing speed, but not memory or verbal ability. After controlling for childhood IQ and SES, current smoking at age 70 (but not pack years of smoking) was associated with impairments in general cognitive ability and processing speed.

CONCLUSION

Smoking in old age makes a small, independent contribution to cognitive performance in old age.

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.

Brain grey matter deficits in smokers: focus on the cerebellum

Structural cerebral deficiencies in smokers have been well characterized by morphometric investigations focussing on cortical and subcortical structures. Although the role of the cerebellum is increasingly noted in mental and addiction disorders, no reports exist regarding cerebellar alterations in smokers employing a methodology specifically designed to assess the cerebellar morphology. We acquired high-resolution MRI scans from 33 heavy smokers and 22 never-smokers and used a voxel-based morphometry (VBM) approach utilizing the Spatially Unbiased Infratentorial (SUIT) toolbox (Diedrichsen 2006) to provide an optimized and fine-grained exploration of cerebellar structural alterations associated with smoking. Relative to never-smokers, smokers showed significant reductions of grey matter volume in the right cerebellum Crus I. The grey matter volume in Crus I correlated negatively with the amount of nicotine dependence as assessed by means of the Fagerström scale. Since Crus I has been identified as the cognitive division of the cerebellum, the structural deficit may in part mediate cognitive deficits previously reported in smokers. Of note, the dependence-related magnitude of the volume deficit may support the notion that the cerebellum is substantially involved in core mechanisms of drug dependence.

Do executive function deficits predict later substance use disorders among adolescents and young adults?

OBJECTIVE

There is increasing interest regarding the risk and overlap of executive function deficits (EFDs) in stable cigarette smoking and substance use disorders (SUD). Therefore, we examined whether earlier EFD was a risk factor for subsequent cigarette smoking and SUD and further explored the relationship between EFD and SUD.

METHOD

We assessed 435 subjects at the 5-year follow-up (232 subjects with attention-deficit/hyperactivity disorder [ADHD], mean age ± SD: 15.4 ± 3.43 years; and 203 controls: 16.3 ± 3.42 years) and again 4 to 5 years later as part of a prospective family study of youth with ADHD. Individuals were assessed by structured psychiatric interview for psychopathology and SUD. EFD was categorically defined in an individual who had abnormal results on at least two of six neuropsychological tests of executive functioning.

RESULTS

At the final follow-up period, ADHD was found to be a significant predictor of stable cigarette smoking (p < .01) and SUD into late adolescence and young adult years (p < .01). However, EFDs were not associated with an increase in subsequent substance use outcomes. New-onset stable cigarette smoking, but not SUD, was associated with subsequent EFD (p < .01).

CONCLUSIONS

Our results do not support the hypothesis that EFDs predicts later stable cigarette smoking or SUD in children with ADHD growing up. However, stable cigarette smoking is associated with subsequent EFD.

Chronic cigarette smoking: implications for neurocognition and brain neurobiology

Compared to the substantial volume of research on the general health consequences associated with chronic smoking, little research has been specifically devoted to the investigation of its effects on human neurobiology and neurocognition. This review summarizes the peer-reviewed literature on the neurocognitive and neurobiological implications of chronic cigarette smoking in cohorts that were not seeking treatment for substance use or psychiatric disorders. Studies that specifically assessed the neurocognitive or neurobiological (with emphasis on computed tomography and magnetic resonance-based neuroimaging studies) consequences of chronic smoking are highlighted. Chronic cigarette smoking appears to be associated with deficiencies in executive functions, cognitive flexibility, general intellectual abilities, learning and/or memory processing speed, and working memory. Chronic smoking is related to global brain atrophy and to structural and biochemical abnormalities in anterior frontal regions, subcortical nuclei and commissural white matter. Chronic smoking may also be associated with an increased risk for various forms of neurodegenerative diseases. The existing literature is limited by inconsistent accounting for potentially confounding biomedical and psychiatric conditions, focus on cross-sectional studies with middle aged and older adults and the absence of studies concurrently assessing neurocognitive, neurobiological and genetic factors in the same cohort. Consequently, the mechanisms promoting the neurocognitive and neurobiological abnormalities reported in chronic smokers are unclear. Longitudinal studies are needed to determine if the smoking-related neurobiological and neurocognitive abnormalities increase over time and/or show recovery with sustained smoking cessation.

Tobacco smoking produces widespread dominant brain wave alpha frequency increases

The major pharmacological ingredient in tobacco smoke is nicotine, a mild stimulant known to alter brain electrical activity. The objective of this study was to determine if tobacco smoking in humans produces localized or widespread neocortical dominant alpha electroencephalographic (EEG) frequency increases consistent with nicotine stimulation of the brainstem activating system in animals. Twenty-two male volunteer non-deprived tobacco smokers were studied. They were asked not to smoke for at least 1h before the experiment in mid-morning as part of their usual smoking schedule. In the laboratory, they sham smoked and then smoked their favorite tobacco cigarette. Two experimental sessions (#1 and #2) were conducted, separated by a one to two month interval. In both sessions, there were minor statistically significant increases in the dominant alpha frequencies after sham smoking. In both sessions, after the subjects smoked a favorite tobacco cigarette there was a significant generalized increase in dominant alpha EEG frequencies in most scalp recording sites. This study demonstrates that tobacco smoking produces widespread bilateral neocortical increases in dominant alpha EEG frequencies consistent with the stimulant effects of nicotine on the brainstem reticular activating system.

Early intervention for cognitive decline: is there a role for multiple medical or behavioural interventions?

AIM

Early medical or behavioural intervention to slow cognitive decline might be a viable strategy for reducing disability and rates of institutional care in older persons. This paper details the published work supporting cross-sectional and longitudinal associations between vascular risk factors, depressive symptoms and progressive cognitive decline. Evidence for the beneficial effects of providing relevant interventions is assessed.

METHODS

Relevant published work from the areas of dementia research, 'vascular depression' and the cognitive benefits that might result from treating vascular risk factors, managing depression or promoting nutrition, cognitive or physical exercise was ascertained from electronic database searches and recent reviews of key areas.

RESULTS

The existing published work does not provide many examples of early intervention strategies that target vascular strategies or active treatment of depression to reduce the rate of cognitive decline. Most studies have major limitations including the evaluation of only single-risk-factor interventions, the observational designs and the inadequate measurement of cognition. An optimal early intervention strategy might be to target multiple risk factors within relevant experimental or health service frameworks.

CONCLUSIONS

Early identification and multifaceted reduction of vascular risk factors, active management of depression, engagement in cognitive activity and physical exercise and promotion of better nutrition might together help to slow some forms of cognitive decline or progression to dementia. This health services approach now requires systematic evaluation.

Smoking, dementia and cognitive decline in the elderly, a systematic review

BACKGROUND

Nicotine may aid reaction time, learning and memory, but smoking increases cardiovascular risk. Cardiovascular risk factors have been linked to increased risk of dementia. A previous meta-analysis found that current smokers were at higher risk of subsequent dementia, Alzheimer's disease, vascular dementia and cognitive decline.

METHODS

In order to update and examine this further a systematic review and meta-analysis was carried out using different search and inclusion criteria, database selection and more recent publications. Both reviews were restricted to those aged 65 and over.

RESULTS

The review reported here found a significantly increased risk of Alzheimer's disease with current smoking and a likely but not significantly increased risk of vascular dementia, dementia unspecified and cognitive decline. Neither review found clear relationships with former smoking.

CONCLUSION

Current smoking increases risk of Alzheimer's disease and may increase risk of other dementias. This reinforces need for smoking cessation, particularly aged 65 and over. Nicotine alone needs further investigation.

Smoking and cognitive decline among middle-aged men and women: the Doetinchem Cohort Study

OBJECTIVES

We studied the effect of smoking on cognitive decline over a 5-year period at middle age (43 to 70 years).

METHODS

In the Doetinchem Cohort Study, 1964 men and women in the Netherlands were examined for cognitive function at baseline and 5 years later. The association between smoking status and memory function, speed of cognitive processes, cognitive flexibility, and global cognitive function were assessed.

RESULTS

At baseline, smokers scored lower than never smokers in global cognitive function, speed, and flexibility. At 5-year follow-up, decline among smokers was 1.9 times greater for memory function, 2.4 times greater for cognitive flexibility, and 1.7 times greater for global cognitive function than among never smokers. Among ever smokers, the declines in all cognitive domains were larger with increasing number of pack-years smoked.

CONCLUSIONS

Interventions to prevent or stop people from smoking may postpone cognitive decline in middle-aged persons.

The effects of cigarette smoking and abstinence on auditory verbal learning

Smoking has been associated with both enhanced and impaired cognitive performance; across a variety of domains, but there is limited evidence demonstrating the effects on verbal learning. The current study assessed the effect of smoking and abstinence on verbal learning, immediate memory and retention using the Auditory Verbal Learning Test (AVLT). Three groups: 20 smokers, 20 abstaining smokers and 20 non-smoking adults were assessed on the AVLT on two occasions. At session one, abstaining smokers refrained from smoking for 12 h (pre-cigarette), whilst smokers had continued to smoke to satiety. Session two commenced after a 15-min break when both smoking groups were instructed to smoke a cigarette, followed by administration of the second version of the AVLT (post-cigarette). Abstaining smokers showed significant deficits in learning compared to smokers during the pre-cigarette session. Following re-initiation of smoking in the abstaining smokers, these learning decrements were no longer evident. There were trends towards significant group findings in immediate memory and retention during the pre-cigarette session, which again were no longer evident in the post-cigarette session. These findings provide further evidence that smoking abstinence affects verbal learning and furthermore smoking simply restores cognitive performance to pre-abstinence levels.

All-cause mortality in the Aberdeen 1921 birth cohort: effects of socio-demographic, physical and cognitive factors

BACKGROUND

Childhood intelligence predicts mortality throughout most of the life span. However, it is unknown whether its effect persists into advanced old age.

METHODS

The Aberdeen Birth Cohort born in 1921 (n = 354) and that had an IQ test as part of the national Scottish Mental Survey of 1932 were seen in 1997 at age 76 years when childhood and adult socio-environmental, medical and cognitive data were collected. Participants were followed until May 2007 and vital status determined from the General Register for Scotland records. Univariate associations between baseline variables and mortality were determined and multivariable survival analysis performed with Cox's proportional hazards modelling.

RESULTS

One hundred and fifty-eight (44.6%) of the 354 cohort members had died by the census date. Significantly more men (n = 102) died during follow-up than women (n = 56, chi2 = 5.27, p = .022). Lower scores on four of the six cognitive tests at age 76 years were associated with increased mortality, but not IQ age 11. Survival was associated with gender (H.R. 0.32, 95% C.I. 0.11-0.89 for women versus men), peak expiratory flow rate (H.R. 0.997, 95% C.I. 0.992-1.001 per l/min) and the Uses of Common Objects test (H.R. 0.91, 95% C.I. 0.82-1.01)

CONCLUSION

Both physical and psychological variables independently predicted survival in old age: respiratory function and executive function in particular. Male gender conferred increased risk of mortality and this was not explained by the broad range of socio-environmental, mental ability and health status variables examined in the study.

Smoking history and cognitive function in middle age from the Whitehall II study

BACKGROUND

Studies about the association between smoking and dementia necessarily involve those who have "survived" smoking. We examine the association between smoking history and cognitive function in middle age and estimate the risk of death and of nonparticipation in cognitive tests among smokers.

METHODS

Data are from the Whitehall II study of 10,308 participants aged 35 to 55 years at baseline (phase 1 [1985-1988]). Smoking history was assessed at phase 1 and at phase 5 (1997-1999). Cognitive data (memory, reasoning, vocabulary, and semantic and phonemic fluency) were available for 5388 participants at phase 5; 4659 of these were retested 5 years later.

RESULTS

Smokers at phase 1 were at higher risk of death (hazard ratio [HR], 2.00; 95% confidence interval [CI], 1.58-2.52 among men and HR, 2.46; 95% CI, 1.80-3.37 among women) and of nonparticipation in cognitive tests (odds ratio [OR], 1.32; 95% CI, 1.16-1.51 among men and OR, 1.69; 95% CI, 1.41- 2.02 among women). At phase 5 in age- and sex-adjusted analyses, smokers compared with those who never smoked were more likely to be in the lowest quintile of cognitive performance. After adjustment for multiple covariates, this risk remained for memory (OR, 1.37; 95% CI, 1.10-1.73). Ex-smokers at phase 1 had a 30% lower risk of poor vocabulary and low verbal fluency. In longitudinal analysis, the evidence for an association between smoking history and cognitive decline was inconsistent. Stopping smoking during the follow-up period was associated with improvement in other health behaviors.

CONCLUSIONS

Smoking was associated with greater risk of poor memory. Middle-aged smokers are more likely to be lost to follow-up by death or through nonparticipation in cognitive tests. Ex-smokers had a lower risk of poor cognition, possibly owing to improvement in other health behaviors.

Blood pressure and cognition in the Aberdeen 1936 birth cohort

BACKGROUND

The relationship between blood pressure and cognition in old age remains unclear. Some data indicate that elevated blood pressure causes cognitive deficits whilst others show that lower early life mental ability predicts high blood pressure in adulthood. Longitudinal studies in which mental ability earlier in life is known are needed to clarify the relationship.

OBJECTIVE

To measure the effect of blood pressure on cognition in late adulthood after adjusting for early life mental ability.

METHODS

The sample comprised survivors of the 1947 Scottish Mental Survey who had validated IQ scores at age 11. Six cognitive tests - Mini-Mental State Examination, Raven's Progressive Matrices, Rey Auditory Verbal Learning Test, Uses of Common Objects Test, Digit Symbol Test and Block Design - were administered at ages 64, 66 and 68 years. Sitting and standing blood pressure was also measured at each wave of follow-up. Mixed general linear models were constructed with each cognitive test treated as a repeated measure of an underlying cognitive trait and with wave of testing also set as a repeated measure. Mental ability at age 11 was entered as a covariate.

RESULTS

504 participants were tested at wave 1 with 368 returning at wave 2 and 300 at wave 3. Age 11 mental ability did not predict any of the blood pressure measures. There were several significant associations between blood pressure variables and cognitive test scores in univariate models. After adjusting for significant effects of wave of testing, type of cognitive test, the interaction between these, age 11 mental ability, age, gender and occupation in a multivariate model, the main effect of BP trait was no longer significant (p = 0.44) nor its effect over time (p = 0.26), though there was a significant interaction between blood pressure trait (BP) and test type with a distinctly negative effect of BP on Auditory Verbal Learning Test (p = 0.007, -0.13 points per mm Hg higher, 95% CI -0.22 to -0.033).

CONCLUSION

The effects of blood pressure on cognition in old age are finely nuanced. Multivariate repeated measures models reveal a differential effect of blood pressure on verbal recall.

The effects of tobacco smoke and nicotine on cognition and the brain

Tobacco smoke consists of thousands of compounds including nicotine. Many constituents have known toxicity to the brain, cardiovascular, and pulmonary systems. Nicotine, on the other hand, by virtue of its short-term actions on the cholinergic system, has positive effects on certain cognitive domains including working memory and executive function and may be, under certain conditions, neuroprotective. In this paper, we review recent literature, laboratory and epidemiologic, that describes the components of mainstream and sidestream tobacco smoke, including heavy metals and their toxicity, the effect of medicinal nicotine on the brain, and studies of the relationship between smoking and (1) preclinical brain changes including silent brain infarcts; white matter hyperintensities, and atrophy; (2) single measures of cognition; (3) cognitive decline over repeated measures; and (4) dementia. In most studies, exposure to smoke is associated with increased risk for negative preclinical and cognitive outcomes in younger people as well as in older adults. Potential mechanisms for smoke's harmful effects include oxidative stress, inflammation, and atherosclerotic processes. Recent evidence implicates medicinal nicotine as potentially harmful to both neurodevelopment in children and to catalyzing processes underlying neuropathology in Alzheimer's Disease. The reviewed evidence suggests caution with the use of medicinal nicotine in pregnant mothers and older adults at risk for certain neurological disease. Directions for future research in this area include the assessment of comorbidities (alcohol consumption, depression) that could confound the association between smoking and neurocognitive outcomes, the use of more specific measures of smoking behavior and cognition, the use of biomarkers to index exposure to smoke, and the assessment of cognition-related genotypes to better understand the role of interactions between smoking/nicotine and variation in genotype in determining susceptibility to the neurotoxic effects of smoking and the putative beneficial effects of medicinal nicotine.