Weight gain and cardiovascular risk factors during smoking cessation with bupropion or nicotine

Meta-analysis of the effects of smoking and smoking cessation on triglyceride levels

Smoking increases lipid levels, including triglycerides, leading to increased cardiovascular disease risk. We performed a meta-analysis to quantify the effects of smoking and smoking cessation on triglyceride levels. The PubMed and Scopus databases were searched to identify studies reporting either triglyceride levels in smokers and non-smokers or the effects of smoking cessation on triglyceride levels. Fixed- and random-effects models were used to perform the analyses when three or more studies/comparisons were available. We identified 169 and 21 studies evaluating the effects of smoking and smoking cessation, respectively, on triglyceride levels. Triglyceride levels were 0.50 mmol/L (95% confidence interval: 0.49-0.50 mmol/L) higher in smokers than non-smokers, but the effect differed widely across studies. No statistically significant effect was observed on triglyceride levels between baseline and 6 weeks (mean difference [MD] = 0.02 [-0.09, 0.12] mmol/L), 2 months (MD = 0.03 [-0.21, 0.27] mmol/L), 3 months (MD = 0.08 [-0.03, 0.21] mmol/L), or 1 year (MD = 0.04 [-0.06, 0.14] mmol/L) after quitting. However, a slightly significant decrease in triglyceride levels was observed at 1 month after cessation (MD = -0.15 [-0.15, -0.01] mmol/L). The results of this meta-analysis provide a basis for understanding the effects of smoking and smoking cessation on triglyceride levels, which could have important implications for public health.

Metabolic parameters in smokers undergoing smoking reduction

Introduction

Few human studies have explored the mechanisms of smoking-induced insulin resistance. Aims: To prospectively examine the metabolic changes of smoking reduction.

Methods

Cigarette smokers (n = 22; ½-2 packs per day) were enrolled in a smoking reduction program (counseling plus bupropion × 8 weeks; Phase I) followed by monitoring only (no counseling or bupropion × 16 weeks; Phase II). We serially measured exhaled carbon monoxide (CO) and urine nicotine metabolites; fat distribution, and metabolic parameters by hyperinsulinemic clamps including hepatic glucose output (HGO) and indirect calorimetry, adjusted for total caloric intake and expenditure.

Results

CO and nicotine metabolite levels fell with smoking reduction during Phase I (all p < 0.05), without any further changes through Phase II. Central-to-peripheral fat ratio increased during Phase I, but then fell during Phase II (all p < 0.05). Over 24 weeks, basal HGO fell (p = 0.02); and falling CO and nicotine metabolite levels correlated inversely with changes in glucose oxidation, and directly with changes in weight (all p < 0.05).

Conclusions

Smoking reduction produced a transient worsening of central fat redistribution followed by a more significant improvement; along with other net beneficial metabolic effects.

Acute one-cigarette smoking decreases ghrelin hormone in saliva: a pilot study

Cigarette smoking is commonly associated with weight loss and mechanisms for these weight changes are still elusive. Ghrelin is a peptide hormone that works in a neuroendocrine fashion to stimulate hunger and the desire for food intake. Ghrelin is also secreted in saliva, probably to enhance food taste. In the current study, we tested the direct impact of acute cigarette smoking on total ghrelin found in saliva. Methods. Blood and saliva samples were collected from 30 healthy nonsmoker male volunteers before and after one-cigarette smoke. Total ghrelin in serum and saliva was measured by ELISA based method. Results. Data showed a statistically significant reduction in salivary ghrelin after smoking (P < 0.0001). In serum, total ghrelin levels were not affected before and after smoking (P = 0.1362). Additionally, positive correlation was observed between serum and salivary ghrelin before smoking (r = 0.4143 and P = 0.0158); however, this correlation was lost after smoking (r = 0.1147 and P = 0.5461). Conclusion. Acute one-cigarette smoking can negatively affect ghrelin levels in saliva that might contribute to the dull food taste in smokers.

Lower but not higher doses of transdermal nicotine facilitate cognitive performance in smokers on gender non-preferred tasks

One of the most widely used treatments for smoking cessation is nicotine replacement therapy (NRT). There is some evidence that smokers experience abstinence-induced deficits in cognitive function, which are attenuated by NRTs. Additionally it's been suggested that the degree of reversal of cognitive deficits may depend on the NRT dose and the smoker's gender. In the present placebo-controlled study we investigated effects of three doses of transdermal nicotine (7 mg, 14 mg and 21 mg) on cognitive performance of 48 male and 48 female smokers after overnight abstinence and 6h of patch application. Cognitive tasks used in the study included the Conners' CPT, emotional Stroop, mental arithmetic, and verbal recall of affective prose passages. The results showed greater probability of attentional problems in the male sample compared to females as identified by the Conners' CPT. Within gender women showed improved performance in the 7 mg and 14 mg conditions on several measures of the Conners' CPT, and faster hit reaction time on the emotional Stroop test compared to women in the placebo and 21 mg of nicotine groups. Conversely, males showed a moderate overall advantage on the mental arithmetic task and were differentially sensitive to nicotine treatment on the prose recall task, on which the greatest improvement in recall of affective material was observed for the 14 mg group compared to the 21 mg group. The results are explained on the basis of an inverted U-shaped relationship between nicotinic stimulation and cognitive performance as well as greater sensitivity to nicotine dose manipulation on gender non-preferred cognitive tasks.

The association between conventional antidepressants and the metabolic syndrome: a review of the evidence and clinical implications

Major depressive disorder is a prevalent recurrent medical syndrome associated with inter-episodic dysfunction. The metabolic syndrome is comprised of several established risk factors for cardiovascular disease (i.e. abdominal obesity, dyslipidaemia, dysglycaemia and hypertension). The criterion items of the metabolic syndrome collectively represent a multi-dimensional risk factor for cardiovascular disease and type 2 diabetes mellitus. Extant evidence indicates that both major depressive disorder and the metabolic syndrome, albeit distinct, often co-occur and are possibly subserved by overlapping pathophysiology and causative mechanisms. Conventional antidepressants exert variable effects on constituent elements of the metabolic syndrome, inviting the need for careful consideration prior to treatment selection and sequencing. Initiating and maintaining antidepressant therapy should include routine surveillance for clinical and/or biochemical evidence suggestive of the metabolic syndrome.

Endocrine and metabolic effects of smoking cessation

BACKGROUND

Cardiovascular, pulmonary, and oncological hazards of tobacco smoking have been well studied. Smoking may also have multiple effects on endocrine and metabolic systems affecting pituitary, thyroid, and adrenal glands; testicular and ovarian function; as well as energy balance; lipid, and glucose metabolism; and insulin resistance. Less is known about hormonal and metabolic effects that patients may experience while quitting smoking.

SCOPE

The objective of this article is to review systematically data on the endocrine and metabolic effects of smoking cessation. Articles based upon clinical trials, randomised controlled trials, and meta-analyses were obtained via a MEDLINE search (articles published between 1 August 1998 and 31 July 2008, inclusive; English language; human subjects; including abstracts) using key search terms relating to smoking cessation and endocrine or metabolic parameters. Additional studies were identified from the bibliographies of reviewed literature. Studies related to the search criteria were reviewed, 199 papers were identified, and 57 pertinent to this review were included.

FINDINGS

Limited data are available on the short- and long-term effects of smoking cessation on hypothalamic- and thyroid-pituitary-adrenal axes, sex hormones, energy homeostasis, and lipid and glucose metabolism. Initial data indicate that smoking cessation is associated with decreased cortisol levels and in the short-term, smoking cessation does not correct the diminished adrenocortical responses to stress caused by chronic smoking. Cessation reverses smoking's effects on thyroid disorders and may reduce the risk of osteoporosis. Finally, smoking cessation increases transiently food intake and sustained weight gain and is associated with increases in high-density lipoprotein cholesterol levels that occur rapidly on cessation.

CONCLUSION

Further research may provide insight into post-cessation endocrine changes that may be caused by alterations to central and peripheral systems. Such research may increase the understanding of underlying biological mechanisms that lead to symptoms and clinical features of smoking cessation.

Respiratory, cardiovascular and other physiological consequences of smoking cessation

BACKGROUND

Smoking cessation is associated with substantial reductions in tobacco-related morbidity and mortality. Based on the current literature, the beneficial effects of quitting are particularly evident on pulmonary and cardiovascular function, but the negative physiological effects of cessation are less well documented.

SCOPE

The objective of this article was to review systematically data on the physiological effects of smoking cessation. Articles based upon clinical trials, randomised controlled trials and meta-analyses were selected from titles and abstracts obtained via a MEDLINE search (May 2003-May 2008). Additional studies were identified from the bibliographies of reviewed literature.

FINDINGS

Smoking cessation is associated with improved lung function and a reduction in the presence and severity of respiratory symptoms. These changes, apparent within months of quitting, are sustained with long-term abstinence. The underlying pathophysiologies of smoking-induced airway inflammation and endothelial dysfunction are partially reversed following cessation in healthy ex-smokers, but not in those with chronic obstructive pulmonary disease. Smoking cessation is also associated with substantially improved cardiovascular function and reduced risk of primary and secondary cardiovascular morbidity and mortality. Although the overall long-term health benefits are unquestionable, smoking cessation is also associated with other possible undesirable short-term physiological effects such as weight gain, hypertension, constipation and mouth ulcers; and altered activity of the enzyme cytochrome P450 1A2 (CYP1A2), which metabolises many commonly used drugs.

CONCLUSION

The negative physiological effects of smoking cessation may adversely affect a smoker's attempt to quit, and physicians should provide their smoking patients with motivation and regular encouragement and support when attempting to quit, whilst educating them on the health benefits of abstinence. Additionally, since cigarette smoke is a potent inducer of CYP1A2, patients attempting to quit smoking should have their dosages of drugs metabolised by this enzyme closely monitored.

Cigarette smoking: an undertreated risk factor for cardiovascular disease

Smoking and other forms of tobacco use are major risk factors for cardiovascular disease. The effect of cigarette smoking on cardiovascular health is evident even at the lowest levels of exposure. Yet, the adverse effects of smoking are reversible, with cardiovascular risk decreasing substantially within the first 2 years of smoking cessation. Significantly, the mortality from coronary heart disease is reduced more through smoking cessation than by other secondary preventive therapies such as cholesterol lowering. Smoking cessation is a highly effective way to improve cardiovascular health in smokers and extremely cost-effective. However, smoking cessation therapies are not implemented maximally if they are implemented at all, perhaps because smoking is seen as a lifestyle choice or because smokers frequently relapse, as indicated by very low long-term quit rates. Too often, healthcare professionals, including lipidologists and cardiologists, do little to address their patients' smoking status, in spite of its impact on cardiovascular health. With the advent of new therapies to treat the nicotine addiction that results from smoking and other tobacco use, it is hoped that physicians will be more proactive in encouraging and implementing smoking cessation programs for their patients, with the goal of increasing long-term quit rates, and reducing the morbidity and mortality associated with cardiovascular disease.

Smoking after cardiac transplantation

Although smoking cessation is a prerequisite prior to listing for cardiac transplantation, some patients return to smoking after recovery. We have covertly assessed the smoking habits of our cardiac transplant recipients (with ethical approval) since 1993 by measuring urinary cotinine: a level of >500 ng/mL signifying continued tobacco use. We retrospectively analyzed survival, causes of death and the development of graft coronary artery disease (GCAD) with respect to the number of positive and negative cotinine levels. One hundred four of 380 (27.4%) patients tested positive for active smoking at some point posttransplant, and 57 (15.0%) tested positive repeatedly. Smokers suffered significantly more deaths due to GCAD (21.2% vs. 12.3%, p < 0.05), and due to malignancy (16.3% vs. 5.8%, p < 0.001). In univariate analysis, smoking after heart transplantation shortened median survival from 16.28 years to 11.89 years. After correcting for the effects of pretransplant smoking in time-dependent multivariate analysis, posttransplant smoking remained the most significant determinant of overall mortality (p < 0.00001). We conclude that tobacco smoking after cardiac transplantation significantly impacts survival by accelerating the development of graft vasculopathy and malignancy. We hope that this information will deter cardiac transplant recipients from relapsing, and intensify efforts in improving cessation rates.

El tabaquismo, la obesidad y la distribución de la grasa corporal se asocian de manera independiente con la resistencia a la insulina y con otros factores de riesgo cardiovascular

BACKGROUND AND AIM

In recent years, smoking has been shown to increase insulin resistance. However, other studies have failed to demonstrate this association after correcting for confounding factors such as age, gender, body mass index (BMI) or waist to hip ratio (WHR). This study was conducted to elucidate the relative contributions of smoking, obesity and body fat distribution on insulin resistance and other cardiovascular risk factors.

PATIENTS AND METHODS

Cases and controls matched for age, gender and degree of obesity. Evaluations included anthropometrical and biochemical assessments with body mass index (BMI), waist to hip ratio (WHR), lipid profiles and insulin resistance determined by HOMA (Homeostasis Model Assessment).

RESULTS AND CONCLUSION

A total of 126 patients (52 smokers and 74 non-smokers) participated in the study. Of all the patients, 22 (17.5%) were lean, 49 (38.9%) overweight and 55 (43.7%) obese. Multivariate stepwise linear regression showed an association of WHR (beta = 0.414, p < 0.001), BMI (beta = 0.211, p = 0.012), the number of smoked cigarettes per day (beta = 0.200, p = 0.011) and serum triglycerides levels (beta = 0.241, p = 0.007) on insulin resistance (R = 0.628, F = 13.841, p < 0.001). An independent effect of smoking on triglycerides levels was also shown. Therefore, smoking, obesity and body fat distribution are independently associated with insulin resistance and lipid profile.

Investigational therapies in the treatment of obesity

Obesity is a major public health concern and environmental factors are involved in its development. The hypothalamus is a primary site for the integration of signals for the regulation of energy homeostasis. Dysregulation of these pathways can lead to weight loss or gain. Some drugs in development can have favourable effects on body weight, acting on some of these pathways and leading to responses resulting in weight loss. Strategies for the management of weight reduction include exercise, diet, behavioural therapy, drug therapy and surgery. Investigational antiobesity medications can modulate energy homeostasis by stimulating catabolic or inhibiting anabolic pathways. Investigational drugs stimulating catabolic pathways consist of leptin, agonists of melanocortin receptor-4, 5-HT and dopamine; bupropion, growth hormone fragments, cholecystokinin subtype 1 receptor agonist, peptide YY3-36, oxyntomodulin, ciliary neurotrophic factor analogue, beta3-adrenergic receptor agonists, adiponectin derivatives and glucagon-like peptide-1. On the other hand, investigational drugs inhibiting anabolic pathways consist of the ghrelin receptor, neuropeptide Y receptor and melanin-concentrating hormone-1 antagonists; somatostatin analogues, peroxisome proliferator-activated receptor-gamma and -beta/delta antagonists, gastric emptying retardation agents, pancreatic lipase inhibitors, topiramate and cannabinoid-1 receptor antagonists. These differing approaches are reviewed and commented on in this article.