Short-term effect of cigarette smoking on CO(2)-induced vasomotor reactivity in man: a study with near-infrared spectroscopy and tanscranial Doppler sonography

Changes in Magnetic Resonance Signal Fluctuation in Superior Sagittal Sinus: Deterioration of Arteriolar Vasomotor Function of Young Smokers

(1) Cerebral arteriolar vasomotor function is vital for brain health and has been examined through CO₂ inhalation or breath-holding, which are both challenging for patients. We have developed a non-invasive method to evaluate this function with magnetic resonance imaging (MRI) by utilizing respiration-induced natural changes in partial pressure of arterial CO₂ (PaCO₂). In this study, we applied this method for 20s to evaluate the chronic effect of a few years smoking on the cerebral arteriolar vasomotor function. (2) A single slice (five slice thicknesses: 15 mm to 7 mm) perpendicular to the superior sagittal sinus of was imaged successively for 45 s using spin-echo echo-planar imaging by 3T MRI for ten smokers (24.5 ± 1.6 years) and ten non-smokers (24.3 ± 1.4 years), respectively. The venous oxygenation fluctuation (ΔY_r) caused by the respiration-induced changes of PaCO₂, which reflects the arteriolar vasomotor function, was calculated from the time series MR signal changes of superior sagittal sinus. (3) The ΔY_r values of the smokers (0.7 ± 0.6) were significantly lower than those of the non-smokers (1.3 ± 0.8) (p = 0.04). (4) Degeneration of the cerebral arteriolar vasomotor function due to chronic smoking (even after 20s) was demonstrated by our non-invasive MRI-based method.

Habitual cigarette smoking attenuates shear-mediated dilation in the brachial artery but not in the carotid artery in young adults

In the present study, we hypothesized that habitual cigarette smoking attenuates endothelial function in the cerebral circulation as well as that of the peripheral circulation in young adults. To test this hypothesis, we measured cerebrovascular and peripheral flow‐mediated dilation (FMD) in young smokers and nonsmokers in the present study. Ten healthy nonsmokers and 10 smokers participated in the study. We measured blood velocity and diameter in the brachial artery and internal carotid artery (ICA) using Doppler ultrasound. We identified shear‐mediated dilation in the brachial artery and ICA by the percentage change in peak diameter during hyperemia stimulation (reactive hyperemia and hypercapnia). We measured the baseline diameter and the shear rate area under the curve from the onset of hyperemia to peak dilation in the brachial artery and ICA, finding the measurements of the smokers and those of the nonsmokers did not differ (p > .05). In contrast to brachial FMD (5.07 ± 1.79% vs. 7.92 ± 3.01%; smokers vs. nonsmokers, p = .019), FMD in the ICA was not attenuated in the smokers compared with that of the nonsmokers (5.46 ± 2.32% vs. 4.57 ± 2.70%; p = .442). These findings indicate that in young healthy smokers, cerebral endothelial function was preserved, and the response of cerebral endothelial function to smoking was different from that of peripheral vasculature.

Combined Effect of Noise and Smoking on the Cognitive Performance of Automotive Industry Workers

Introduction:

Noise is an environmental stressor and can cause or exacerbate mental disorders, and affect the individual performance in certain conditions. This study aimed to evaluate the combined effects of noise and smoking on the cognitive performance of the workers in the automotive industry.

Methods:

This research is a descriptive-analytical study with a cross-sectional design conducted on 300 workers randomly assigned into two groups of noise-exposed and nonexposed. They were examined using computerized tests, including the Tower of London test (TOL), Continuous Performance test (CPT), and Stroop test. The sound pressure levels were measured based on an 8-hour equal-loudness contour in each group according to ISO 9612 standard, using the Testo CEL-815 sound level meter.

Results:

The study of combined effects of noise and smoking on 12 CPT indicators using the 2-way Analysis of Variance (ANOVA) indicate that noise and smoking factors had a significant impact on the mean number of errors and correct responses in the third 50-stimuli stage, the mean number of errors and correct responses in the second 50-stimuli stage with P<0.001, P<0.001, P=0.012 and P<0.001 for smoking respectively, but only noise affected the other 7 indicators (P<0.001).

Conclusion:

Smoking and noise have negative impacts on concentration, attention, and cognitive processing speed, which can lead to an individual’s mistakes and delayed decision making at the workplace.

Evaluation of cerebrovascular reactivity in chronic hepatitis C patients using transcranial color Doppler

Hepatitis C viral (HCV) infection is associated with systemic inflammation and metabolic complications that might predispose patients to atherosclerosis, including cerebrovascular atherosclerosis. The aim of this study was to assess cerebrovascular reactivity in patients with chronic hepatitis C. Seventeen patients with chronic hepatitis C infection, as well as 11 healthy blood donors in the control group, were assessed for cerebrovascular reactivity according to the well-established breath-holding test that uses the transcranial color Doppler for measurement of blood flow velocity. Results obtained during the breath-holding revealed significantly lower average peak systolic (AvPS start, P = 0.018), end-diastolic (AvED start, P = 0.031) and mean velocity values at the very beginning of the breath-holding procedure (AvmeanV start, P = 0.02), as well as a lower mean peak systolic velocity at the end of the breath-holding test (AvPS max, P = 0.02) in the hepatitis C group. Vascular reactivity values, calculated as the breath-holding index, were also significantly lower (P = 0.045) in the hepatitis C group. In conclusion, the results of this study suggest an association between chronic HCV infection and altered cerebrovascular reactivity which may ultimately have an unfavorable effect on cerebrovascular hemodynamics and lead to increased risk of cerebrovascular diseases.

Time to First Cigarette and Self-Reported Health Among US Adult Smokers

Background:

Numerous studies have reported that shorter time to first cigarette (TTFC) is linked to elevated risk for smoking-related morbidity. However, little is known about the influence of early TTFC on self-reported health among current smokers. Hence, the objective of this study was to examine the association between TTFC and self-reported health among US adult smokers.

Methods:

Data came from the 2012-2013 National Adult Tobacco Survey (NATS). Current smokers aged 18 years and older (N = 3323) were categorized into 2 groups based on TTFC: ≤ 5 minutes (n = 1066) and >5 minutes (n = 2257). Propensity score matching (PSM) was used to control selection bias.

Results:

After adjusting for sociodemographic and smoking behavior factors, current smokers with early TTFC had higher odds for poor health in comparison with current smokers with late TTFC in the prematching (adjusted odds ratio [AOR] = 1.65; 95% confidence interval [CI] = 1.31-2.08) and postmatching (AOR = 1.60; 95% CI = 1.22-2.09) samples.

Conclusions:

In conclusion, smokers with early TTFC were associated with increased risk of poor health in the United States. To reduce early TTFC, elaborate efforts are needed to educate people about harms of early TTFC and benefits of stopping early TTFC.

Exercise performance increase in smokeless tobacco-user athletes after overnight nicotine abstinence

The use of nicotine administered through smokeless tobacco (snus) has increased among athletes. The purpose of this study was to investigate the ergogenic effects of snus on aerobic performance during exercise until exhaustion in athletes after abstinence or satiety nicotine conditions. The study utilized a randomized, controlled, within-subject design experiment. Sixteen male snus-user athletes completed an exercise until exhaustion at a constant load of their 80% of V ˙ O 2 max (calculated by a maximal incremental test) in two separate sessions, corresponding to nicotine conditions: 12-hour overnight abstinence and satiety. A portion of 1 g of snus (~8 mg/g of nicotine) was administered 25 minutes before each experimental test. In each session, time to exhaustion (TTE), global rating of perceived exertion, cardiovascular and metabolic responses, and muscle and cerebral oxygenation were measured. Nicotine and cotinine analysis confirmed session conditions (abstinence or satiety). Snus induced a significant increase (+13.1%) of TTE following abstinence (24.1 ± 10.7 minutes) compared to satiety condition (20.9 ± 8.0 minutes; P = 0.0131). The baseline values revealed that abstinence of snus induced significant increase in the oxygenation of the muscular tissues (+4%), in metabolic values and in cardiovascular parameters, when compared to satiety condition. Our results indicate an increase of exercise performance (+13.1% TTE) due to snus administration in an abstinence condition. Considering that twelve hours of abstinence from snus-contained nicotine affected metabolic, cardiovascular and muscular tissue oxygenation, we suggest that snus administration at test time might relieve these withdrawal changes and yield an increase in time to exhaustion.

Regional cerebral blood flow in opiate dependence relates to substance use and neuropsychological performance

Neuroimaging of opiate-dependent individuals indicates both altered brain structure and function. Magnetic resonance-based arterial spin labeling has been used to measure noninvasively cerebral blood flow (i.e. perfusion) in alcohol, tobacco and stimulant dependence; only one arterial spin labeling paper in opiate-dependent individuals demonstrated frontal and parietal perfusion deficits. Additional research on regional brain perfusion in opiate dependence and its relationship to cognition and self-regulation (impulsivity, risk taking and decision making) may inform treatment approaches for opiate-dependent individuals. Continuous arterial spin labeling magnetic resonance imaging at 4 T and neuropsychological measures assessed absolute brain perfusion levels, cognition and self-regulation in 18 cigarette smoking opiate-dependent individuals (sODI) stable on buprenorphine maintenance therapy. The sODI were compared with 20 abstinent smoking alcohol-dependent individuals (a substance-dependent control group), 35 smoking controls and 29 nonsmoking controls. sODI had lower perfusion in several cortical and subcortical regions including regions within the brain reward/executive oversight system compared with smoking alcohol-dependent individuals and nonsmoking controls. Perfusion was increased in anterior cingulate cortex and globus pallidus of sODI. Compared with all other groups, sODI had greater age-related declines in perfusion in most brain reward/executive oversight system and some other regions. In sODI, lower regional perfusion related to greater substance use, higher impulsivity and weaker visuospatial skills. Overall, sODI showed cortical and subcortical hypoperfusion and hyperperfusion. Relating to neuropsychological performance and substance use quantities, the frontal perfusion alterations are clinically relevant and constitute potential targets for pharmacological and cognitive-based therapeutic interventions to improve treatment outcome in opiate dependence.

Young smoker "ABCD" vascular assessment: a four-step ultrasound examination for detecting peripheral, extra and intra-cranial early arterial damage

Background

Cigarette smoking is known as a major risk factor in the pathogenic mechanisms of stroke, coronary and peripheral artery disease (CAD and PAD), even in young subjects. The aim of this study is the creation of a four-step ultrasound examination to evaluate and monitor the peripheral, the extra and the intra-cranial assessment of the arterial early damage in smokers. The evaluations of A, the Ankle-brachial index, ABI, B, the Breath holding index, BHI, C, the Carotid intima media thickness, CIMT, and D, the Diameter of the abdominal aorta represent the “ABCD” assessment.

Methods

Thirty-eight healthy smokers and 43 controls underwent A, calculated for each leg. B was calculated after determination of subjects’ flow velocity of middle cerebral artery (MCA) by trans-cranial colour Doppler (TCCD) before and after 30 s of apnoea at baseline and just after smoking a cigarette, to simulate the chronic and acute effects of smoking. Finally, C and D evaluation were assessed using a high-resolution B-mode ultrasound.

Results

Smokers presented higher values of CIMT (mean and maximal), and lower BHI both at baseline and just after smoking (p < 0.01), though in the normal range. No significant differences were found for A and D between smokers and non- smokers.

Conclusions

Our results underline the importance of the assessment of B and C, that, though in the normal range, present significant differences between smokers and non-smokers. These data could drive the screening between smokers in age-related manner. Moreover, the “ABCD” examination could represent a valid method to detect and then monitor smokers’ vascular damage. Although it is far to be considered a screening and routine tool, it should be contemplated in a wider context of possible not-invasive practical screening and follow-up modalities. This would be designed to implement preventive strategies and tools aimed at discouraging tobacco addiction and monitoring cardiovascular risk patients.

Time to First Cigarette and Hypertension in Korean Male Smokers

Background

Morning blood pressure surge affects to cardiovascular disease risk. Short time to first cigarette (TTFC) after waking can enhance morning blood pressure surge, and accelerate atherosclerosis

Methods

We investigated that the relationship between TTFC and blood pressure. The study subjects included male current smokers (n=211) who had health check-up in Hallym University Sacred Heart Hospital from July to September, 2014. We categorized the subjects into 2 groups according to TTFC; early TTFC (TTFC <30 minutes) and late TTFC (TTFC ≥30 minutes), and the subjects who were taking antihypertensive medications or had a high blood pressure (>140 mm Hg or 90 mm Hg) were defined as hypertensive group. Multivariate logistic regression was performed to estimate the odds ratio and 95% confidence interval to investigate the association between TTFC and hypertensive group.

Results

Compared with late TTFC, early TTFC had higher odds (odds ratio [OR], 3.87; 95% confidence interval [CI], 1.89-7.94) for hypertensive group. After adjusting confounding factors, early TTFC was significantly associated with an increased risk of hypertension (OR, 4.43; 95% CI, 1.84-10.70).

Conclusion

early TTFC after waking is associated with hypertension. It suggests delaying TTFC might help to control of blood pressure among the current smokers who are not ready to immediately quit smoking.

Comparison of Regional Brain Perfusion Levels in Chronically Smoking and Non-Smoking Adults

Chronic cigarette smoking is associated with numerous abnormalities in brain neurobiology, but few studies specifically investigated the chronic effects of smoking (compared to the acute effects of smoking, nicotine administration, or nicotine withdrawal) on cerebral perfusion (i.e., blood flow). Predominately middle-aged male (47 ± 11 years of age) smokers (n = 34) and non-smokers (n = 27) were compared on regional cortical perfusion measured by continuous arterial spin labeling magnetic resonance studies at 4 Tesla. Smokers showed significantly lower perfusion than non-smokers in the bilateral medial and lateral orbitofrontal cortices, bilateral inferior parietal lobules, bilateral superior temporal gyri, left posterior cingulate, right isthmus of cingulate, and right supramarginal gyrus. Greater lifetime duration of smoking (adjusted for age) was related to lower perfusion in multiple brain regions. The results indicated smokers showed significant perfusion deficits in anterior cortical regions implicated in the development, progression, and maintenance of all addictive disorders. Smokers concurrently demonstrated reduced blood flow in posterior brain regions that show morphological and metabolic aberrations as well as elevated beta amyloid deposition demonstrated by those with early stage Alzheimer disease. The findings provide additional novel evidence of the adverse effects of cigarette smoking on the human brain.

Brain perfusion in polysubstance users: relationship to substance and tobacco use, cognition, and self-regulation

BACKGROUND

Brain perfusion is altered in both alcohol dependence and stimulant dependence. Although most substance users also abuse/depend on alcohol concurrently (polysubstance users; PSU), rigorous perfusion research in PSU is limited. Also, the relationships of perfusion abnormalities with cognition, impulsivity, or decision making are not well known.

METHODS

Arterial spin labeling MRI and neuropsychological measures assessed perfusion levels and neurocognition in 20 alcohol-dependent individuals with comorbid-stimulant dependence (PSU), 26 individuals dependent on alcohol only (ALC), and 31 light/non-drinking controls (LD). The patient groups included smokers and non-smokers.

RESULTS

ALC had lower perfusion than LD in subcortical and cortical brain regions including the brain reward/executive oversight system (BREOS). Contrary to our hypothesis, regional perfusion was generally not lower in PSU than ALC. However, smoking PSU had lower perfusion than smoking ALC in several regions, including BREOS. Lower BREOS perfusion related to greater drinking severity in smoking substance users and to greater smoking severity in smoking ALC. Lower regional perfusion in ALC and PSU correlated with worse performance in different cognitive domains; smoking status affected perfusion-cognition relationships in ALC only. Lower BREOS perfusion in both substance using groups related to higher impulsivity.

CONCLUSION

Although regional perfusion was not decreased in PSU as a group, the combination of cigarette smoking and polysubstance use is strongly related to hypoperfusion in important cortical and subcortical regions. As lower perfusion relates to greater smoking severity, worse cognition and higher impulsivity, smoking cessation is warranted for treatment-seeking PSU and ALC.

Influence of smoking cigarettes on cerebral blood flow parameters

INTRODUCTION

While chronic cigarette smoking can lead to increased risk of stroke, the acute effects of smoking have not been established. We studied the changes in blood flow parameters in the major cerebral arteries caused by smoking one cigarette.

METHOD

Using transcranial color-coded sonography (TCCS), we studied the anterior cerebral artery (ACA), middle cerebral artery (MCA), posterior cerebral artery (PCA), and the internal carotid artery (ICA) of 36 healthy male volunteers before and after they smoked one cigarette.

RESULTS

Blood flow velocity increased to a different degree in all but one of the arteries examined after participants smoked a single cigarette: The end diastolic velocity increased significantly by 7.8% in the PCA, 8% in the ACA, and 14.4% in the MCA. The peak systolic velocity increased significantly by 7.5% in the MCA. Blood flow velocity remained unchanged in the ICA only. Blood pressure and heart rate increased as did the flow velocity ratio for the MCA/ICA. The pulsatility index decreased after smoking from 0.92 ± 0.13 to 0.87 ± 0.14 in the MCA, 0.93 ± 0.15 to 0.87 ± 0.13 in the ACA, and 0.95 ± 0.17 to 0.89 ± 0.16 in the PCA.

CONCLUSIONS

The results suggest that the direct effect of smoking on cerebral circulation includes peripheral vasodilatation with possible constriction of the main trunk of the basal cerebral arteries.

Prefrontal hemodynamic changes during cigarette smoking in young adult smokers with and without ADHD

Individuals with attention-deficit/hyperactivity disorder (ADHD) have elevated smoking prevalence and reduced cessation rates compared to the general population. However, the effects of cigarette smoking on underlying brain activity in smokers with ADHD are not well characterized. Non-invasive near-infrared spectroscopy (NIRS) was used to characterize how cigarette smoking affects prefrontal brain hemodynamics in smokers with and without ADHD. Prefrontal changes of oxy- and deoxyhemoglobin (HbO2 and HHb) were measured in six male adult smokers with ADHD and six age- and gender-matched control smokers. NIRS measurements were separated into four sequential time intervals, i.e., before smoking, during smoking, after smoking, and during a breath hold. Prefrontal HbO2 was lower during smoking in smokers with ADHD compared to control smokers. More specifically, smokers with ADHD showed decreased prefrontal HbO2 during smoking compared to breath hold, before and after smoking periods. In contrast, control smokers showed increased prefrontal HbO2 from before smoking to breath hold. Decreased prefrontal HbO2 in smokers with ADHD may reflect a smoking-induced change in prefrontal brain activity and microvasculature, which is not found in smokers without ADHD. The lower prefrontal HbO2 may be a biomarker for increased susceptibility to tobacco smoke in smokers with ADHD. Smoking in individuals with ADHD may increase vasoconstriction of cerebral arteries in the prefrontal cortex, which may contribute to a reduction in HbO2. The findings highlight the importance of smoking cessation, in particular in those smokers who use nicotine to self-medicate ADHD symptoms.

The influence of tobacco smoking on the relationship between pressure and flow in the middle cerebral artery in humans

Background

Cigarette smoking is associated with an increased risk of stroke but the mechanism is unclear. The study examined whether acute and chronic cigarette smoking alters the dynamic relationship between blood pressure and cerebral blood flow. We hypothesised that acute and chronic smoking would result in a cerebral circulation that was less capable of buffering against dynamic fluctuations in blood pressure. Further, these changes would be accompanied by a reduction in baroreflex sensitivity, which is reduced after smoking (acute smoking).

Methods

We recruited 17 non-smokers and 15 habitual smokers (13 ± 5 pack years). Continuous measurements of mean cerebral blood flow velocity (transcranial Doppler ultrasound), blood pressure (finger photoplethysmography) and heart rate enabled transfer function analysis of the dynamic relationship between pressure and flow (gain, normalised gain, phase and coherence) and baroreflex sensitivity during supine rest before and after smoking a single cigarette (acute smoking).

Results

There were no between-group differences in gain, phase or coherence before acute smoking. However, both groups showed a reduction in gain and coherence, associated with a reduction in baroreflex sensitivity, and increase in phase after acute smoking.

Conclusions

Contrary to our hypothesis, these findings suggest that in the face of a reduction in baroreflex sensitivity acute smoking may potentially improve the ability of the cerebral circulation to buffer against changes in blood pressure. However, chronic smoking did not alter the dynamic relationship between blood pressure and cerebral blood flow velocity. These results have implications on understanding mechanisms for attenuating stroke risk.

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.

Cerebrovascular reactivity, intima-media thickness, and nephropathy presence in patients with type 1 diabetes

OBJECTIVE

Cerebrovascular reactivity impairment was reported as a marker of cerebral microangiopathy in long-term type 1 diabetes. Intima-media complex thickening reflects early stages of macroangiopathy in type 1 diabetes. The analysis of the relationship between these variables and other microangiopathic complications might serve as a beneficial indicator for early prophylaxis in these patients.

RESEARCH DESIGN AND METHODS

Vasomotor reactivity reserve (VMRr) and breath-holding index (BHI) of the middle cerebral artery were measured with transcranial Doppler in 59 patients (median age 32.0 years, range 20-51, 36 females) with type 1 diabetes, without history of cerebrovascular events, and 30 healthy control subjects (median age 31.5 years, range 25-39, 15 females). The relationships between the presence of selected vascular complications of type 1 diabetes and biochemical parameters, intima-media thickness (IMT), and VMRr and BHI in patients were analyzed.

RESULTS

VMRr and BHI were lower in patients with type 1 diabetes when compared with healthy subjects (81.5 vs. 100%, P < 0.01, and 1.6 vs. 2.2, P = 0.04, respectively), whereas IMT was significantly higher in patients then in healthy control subjects (0.36 vs. 0.30 mm, P = 0.001). However, no association of IMT with VMRr was found. We found a significant reduction of VMRr and BHI in patients with diabetic nephropathy.

CONCLUSIONS

The presence of diabetic nephropathy, but not IMT, can be regarded as an indicator of cerebral microangiopathy severity in patients with type 1 diabetes.

Influence of galantamine on vasomotor reactivity in Alzheimer's disease and vascular dementia due to cerebral microangiopathy

BACKGROUND AND PURPOSE

Recent reports suggest that vascular factors play a crucial role in the development and progression of Alzheimer's disease. We aimed to assess vasomotor reactivity in patients with Alzheimer's disease and vascular dementia due to microangiopathy using transcranial Doppler sonography and near-infrared spectroscopy during a CO(2) exposition task.

METHODS

The normalized CO(2) reactivity assessed at the middle cerebral artery and the oxygenated and deoxygenated hemoglobin of the frontal cortex were obtained. To investigate the impact of cholinergic deficiency known for Alzheimer's disease on vasomotor reactivity, both groups were reinvestigated during treatment with the acetylcholine esterase inhibitor galantamine.

RESULTS

Transcranial Doppler analysis revealed significantly reduced normalized CO(2) reactivity for Alzheimer's disease and vascular dementia. Vasomotor reactivity assessed by near-infrared spectroscopy was decreased in patients with vascular dementia, but not in Alzheimer's disease. Galantamine treatment showed a beneficial effect, normalizing these parameters close to age-matched control levels.

CONCLUSIONS

Our results suggest that Alzheimer's disease is associated with a lack of vasomotor reactivity, which might be associated with disturbed autoregulation indicating a potential risk for a decreased protection of brain tissue against blood pressure changes. Additionally, a diminished increase of cortical oxygenated hemoglobin during the CO(2) test was apparent in patients with vascular dementia. Galantamine treatment influenced vascular reactivity in the CO(2) test, thus providing evidence for the cholinergic deficiency, thereby adding to vascular dysregulation in Alzheimer's disease, but also indicating an important role of cholinergic system dysfunction for vascular dementia.

Alcohol drinking and cognitive functions: findings from the Cardiovascular Risk Factors Aging and Dementia (CAIDE) Study

BACKGROUND

Moderate alcohol drinking is suggested to be beneficial for cognitive functions, but the results of previous studies have varied greatly. Little is known about the effects of midlife alcohol drinking on the cognitive functions later in life.

METHODS

Participants were derived from random, population-based samples studied in Eastern Finland in 1972, 1977, 1982, or 1987. A total of 1,341 participants were reexamined in 1998, after an average follow-up period of 21 years, at ages 65-79 years.

RESULTS

The participants who did not drink alcohol at midlife had a poorer performance in episodic memory, psychomotor speed, and executive function in late life as compared with infrequent and frequent drinkers, adjusted for sociodemographic and vascular factors. Also late-life nondrinkers had poorer psychomotor speed and executive function. These findings were evident especially among nonsmokers. Further, no interactions between apolipoprotein E4 and alcohol or sex and alcohol were found.

CONCLUSIONS

Alcohol drinking both at midlife and later is favorably related to the function in several cognitive domains, including episodic memory, psychomotor speed, and executive function, in late life. However, it is not clear whether the association is causal, what is the possible mechanism, and what would be a safe limit of drinking for the best cognitive function.

Inhalation of ultrafine and fine particulate matter disrupts systemic vascular function

This study investigated the effects of particulate matter (PM) with aerodynamic diameter 0.02-1 microm (noted as PM1) inhalation during exercise on conduit artery and microvascular function. Inhalation of internal combustion-derived PM is associated with cardiovascular mortality and morbidity. Direct action of PM on the vascular endothelium is likely, as a substantial fraction of ultrafine PM translocates from the alveoli to the circulatory system. Sixteen intercollegiate athletes performed 30 min of exercise while inhaling low or high PM1. Flow-mediated brachial artery dilation (FMD) using high-resolution ultrasonography with simultaneous measurements of forearm oxygen kinetics using near infrared spectrophotometry (NIRS) was done before and after exercise. Basal brachial artery vasoconstriction was found after high PM1 exercise (4.0%, 4.66 +/- 0.609 to 4.47 +/- 0.625 mm diameter; p = .0002), but not after low PM1 exercise (-0.3%, 4.66 +/- 0.626 to 4.68 +/- 0.613 mm diameter). FMD was impaired after high PM1 exercise (6.8 +/- 3.58% for preexercise FMD and 0.30 +/- 2.74% for postexercise FMD, p = .0001), but not after low PM1 exercise (6.6 +/- 4.04% for preexercise FMD and 4.89 +/- 4.42% for postexercise FMD). Reduction in forearm muscle reperfusion estimated by reoxygenation slope-to-baseline after 4 min cuff ischemia was observed for high PM1 exercise (55% vs. 3%, p = .0006); no difference was noted for low PM1 exercise. Brachial artery FMD was significantly correlated to muscle reoxygenation slope-to-baseline (r = .50, p = .005). Acute inhalation of high [PM1] typical of urban environments impairs both systemic conduit artery function and microcirculation. The observed decrease reoxygenation slope-to-baseline after cuff release is consistent with reduced blood flow in the muscle microvasculature.

Effects of chronic alcohol dependence and chronic cigarette smoking on cerebral perfusion: a preliminary magnetic resonance study

BACKGROUND

Although approximately 80% of individuals with alcohol use disorders are chronic smokers and despite reported associations between chronic cigarette smoking and lower cerebral perfusion in nonalcoholics, previous brain perfusion studies with alcoholics did not account for the potential effects of concurrent chronic cigarette smoking.

METHODS

One-week-abstinent alcohol-dependent individuals in treatment (ALC) [19 smokers (sALC) and 10 nonsmokers (nsALC)] and 19 healthy light drinking, nonsmoking control participants (nsLD) were scanned with a pulsed arterial spin labeling method to measure cerebral perfusion without an exogenous contrast agent. Studies were performed with 2 different postlabeling delay times (time from labeling pulse to the excitation pulse; PLD=1,500 ms and PLD=1,200 ms) to assess the potential effect of arterial blood transit time on the perfusion. Average gray matter (GM) and white matter (WM) perfusion for the frontal and parietal lobes were calculated for each hemisphere from voxels containing at least 90% GM and 100% WM.

RESULTS

At PLD=1,500 ms, multivariate analyses compared ALC (combined sALC and nsALC) with nsLD (p=0.04) and contrasted sALC, nsALC, and nsLD (p=0.006). ALC, as a group, showed 13% lower frontal GM perfusion (p=0.005) and 8% lower parietal GM perfusion than nsLD (p=0.03). With ALC separated into smokers and nonsmokers, sALC showed 19% lower frontal GM perfusion (p=0.001) and 12% lower parietal GM perfusion than nsLD (p=0.004). In sALC, a higher number of cigarettes smoked per day was associated with lower perfusion. Overall, regional perfusion did not differ significantly between nsALC and nsLD. Results obtained with PLD=1,200 ms generally confirmed the 1,500 ms findings.

CONCLUSIONS

This study provides preliminary evidence that chronic cigarette smoking adversely affects cerebral perfusion in frontal and parietal GM of 1-week-abstinent alcohol-dependent individuals. These results are in line with our spectroscopic and structural magnetic resonance studies that suggest chronic cigarette smoking compounds the detrimental effects of alcohol dependence on brain neurobiology.

Relationship between oxygen supply and cerebral blood flow assessed by transcranial Doppler and near-infrared spectroscopy in healthy subjects during breath-holding

Background

Breath – holding (BH) is a suitable method for inducing cerebral vasomotor reactivity (VMR). The assessment of VMR is of clinical importance for the early detection of risk conditions and for the follow-up of disabled patients. Transcranial Doppler ultrasonography (TCD) is used to measure cerebral blood flow velocity (CBFV) during BH, whereas near-infrared spectroscopy (NIRS) measures the concentrations of the oxygenated (O₂Hb) and reduced (CO₂Hb) hemoglobin. The two techniques provide circulatory and functional-related parameters. The aim of the study is the analysis of the relationship between oxygen supply and CBFV as detected by TCD and NIRS in healthy subjects performing BH.

Methods

20 healthy subjects (15 males and 5 females, age 33 ± 4.5 years) underwent TCD and NIRS examination during voluntary breath – holding. VMR was quantified by means of the breath-holding index (BHI). We evaluated the BHI based on mean CBFV, O₂Hb and CO₂Hb concentrations, relating the baseline to post-stimulus values. To quantify VMR we also computed the slope of the linear regression line of the concentration signals during BH. From the NIRS signals we also derived the bidimensional representation of VMR, plotting the instantaneous O₂Hb concentration vs the CO₂Hb concentration during the BH phase. Two subjects, a 30 years old current smoker female and a 63 years old male with a ischemic stroke event at the left middle cerebral artery, were tested as case studies.

Results

The BHI for the CBFV was equal to 1.28 ± 0.71 %/s, the BHI for the O₂Hb to 0.055 ± 0.037 μmol/l/s and the BHI for CO₂Hb to 0.0006 ± 0.0019 μmol/l/s, the O₂Hb slope was equal to 0.15 ± 0.09 μmol/l/s and the CO₂Hb slope to 0.09 ± 0.04 μmol/l/s. There was a positive correlation between the CBFV and the O₂Hb increments during BH (r = 0.865). The bidimensional VMR pattern shows common features among healthy subjects that are lost in the control studies.

Conclusion

We show that healthy subjects present a common VMR pattern when counteracting cerebral blood flow perturbations induced by voluntary BH. The proposed methodology allows for the monitoring of changes in the VMR pattern, hence it could be used for assessing the efficacy of neurorehabilitation protocols.

Cerebral hemodynamics in symptomatic and asymptomatic patients with severe unilateral carotid stenosis before and after carotid endarterectomy

BACKGROUND

Data concerning hemodynamic status prior to and after carotid endarterectomy (CEA) in symptomatic and asymptomatic patients is insufficient. Transcranial Doppler (TCD) provides information regarding compensatory collateral flow as well as mechanisms of cerebral autoregulation in patients with carotid stenosis.

PATIENTS AND METHODS

Forty eight symptomatic and 81 asymptomatic patients with unilateral severe carotid stenosis were examined by TCD before and in early postoperative period after CEA.

RESULTS

Cigarette smoking was the only risk factor significantly more frequent in symptomatic patients. Preoperative anterior cerebral artery (ACA) and middle cerebral artery (MCA) asymmetry, basilar artery velocity and number of ophthalmic arteries with reversed flow, were not significantly different between the two groups. Pulsatility index, cerebrovascular reactivity and flow acceleration on the side of stenosis were significantly lower in symptomatic patients. After surgery there was a significant improvement of all TCD parameters in symptomatic as well as asymptomatic patients.

CONCLUSIONS

The exhausted ability of cerebral autoregulation is an important factor differentiating between symptomatic and asymptomatic patients with severe carotid stenosis. Successful surgery provides good recovery of cerebral hemodynamics in both symptomatic and asymptomatic patients.

Angiotensin II type 1 (AT1)-receptor blocker prevents impairment of endothelium-dependent cerebral vasodilation by acute cigarette smoking in rats

Our aim was to test for smoking-induced endothelial dysfunction in rat cerebral vessels, then to evaluate the effect of valsartan [angiotensin II type I (AT1)-receptor blocker] on that impairment. In pentobarbital-anesthetized, mechanically ventilated Sprague-Dawley rats, we used a cranial window preparation to measure changes in pial vessel diameters following topical applications of acetylcholine (Ach) (before and after smoking or intravenous nicotine infusion; n = 6 in each group), and adenosine (n = 6 for before and after smoking). Then, after intravenous valsartan pretreatment we reexamined the pial vasodilator response to topical Ach (before and after cigarette smoking). Under control conditions, cerebral arterioles were dilated by 6.9 +/- 4.2% and 13.6 +/- 4.8% by topical Ach (10(-6) M and 10(-5) M, respectively) and by 6.4 +/- 2.5% and 12.2 +/- 3.1% by topical adenosine (10(-5) M and 10(-4) M, respectively). One hour after a 1-min inhalation of mainstream smoke (1-mg nicotine cigarette), 10(-5) M Ach constricted cerebral arterioles (-4.4 +/- 4.1%), while 10(-4) M adenosine dilated them by 13.4 +/- 3.4%. One hour after a 1-min nicotine infusion (0.05 mg), 10(-5) M Ach dilated cerebral arterioles by 9.9 +/- 2.4%. Thus, vasodilator response to topical Ach was impaired after smoking, whereas that to adenosine was unaffected. However, the vasodilator response to Ach was unaffected by intravenous nicotine. Valsartan prevented smoking from impairing Ach-induced vasodilation. In conclusion, acute single-cigarette smoking causes a dysfunction of endothelium-dependent, but not endothelium-independent, vasodilation of rat cerebral vessels in vivo, and the effect was not mimicked by intravenous nicotine. AT1-receptor blockade prevented the above smoking-induced impairment of endothelium-dependent vasodilation.

Smoking as a crucial independent determinant of stroke

Background

Although smoking is known to be powerful risk factor for other vascular diseases, such as cardiac and peripheral vascular disease, only relatively recently has evidence for the role of smoking in the development of stroke been established. The reasons for this advance lie in the acknowledgement that stroke is a heterogeneous disease, in which its subtypes are associated with different risk factors. Furthermore, improvements in the stringency of epidemiological studies and the greater use of CT scanning have enabled the role of smoking in the development of stroke to be elucidated.

Summary of review

This is a qualitative examination of high quality epidemiological studies in which the role of smoking and passive smoking, as a risk factor for cerebral infarction, intracerebral haemorrhage and subarachnoid haemorrhage, is examined. In addition, the pathological mechanisms by which smoking or passive smoking may contribute to the development of stroke are reviewed.

Conclusion

Smoking is a crucial independent determinant of cerebral infarction and subarachnoid haemorrhage, however its role in intracerebral haemorrhage is unclear. Although studies are limited, there is evidence that exposure to passive smoking may also increase the risk of stroke. Smoking appears to be involved in the pathogenesis of stroke via direct injury to the vasculature and also by altering haemodynamic factors within the circulation. Importantly, smoking is modifiable risk factor for stroke. Therefore, the encouragement of smoking cessation may result in a substantial reduction in the incidence of this devastating disease.