Epilepsy and the Interictal State

Co-morbidities and Quality of Life

Erik K. St Louis, David M. Ficker, Terence J. O'Brien

• Publisher: Wiley-Blackwell
• Year: 2015
• Print ISBN: 9780470656235
• eBook ISBN: 9781118951019
• Edition: 1
• Topic: Medicine
• Subtopic: Neurology

Epilepsy care traditionally focuses on seizures, yet for most epilepsy sufferers, other interictal factors such as mood, cognitive abilities, and treatment adverse effects most influence how they feel and function day to day.

Epilepsy and the Interictal State is a practical and comprehensive text that covers quality of life issues, cognition and therapy, adverse effects of epilepsy treatments, mood state and psychiatric co-morbidity and general health aspects of epilepsy. Each chapter employs a standard structure providing background, epidemiology, pathophysiology, etiology, diagnosis, treatment, prognosis and further practical advice.

From an international team of expert editors and contributors, Epilepsy and the Interictal State is a valuable resource for specialist epileptologists and neurologists, as well as for neurosurgeons, neurology nurses, psychiatrists, family physicians and general practitioners.

Section V

General health and epilepsy

CHAPTER 17
Obesity and epilepsy

Sandra J. Petty¹ and Alison M. Pack²

¹The Florey Institute of Neuroscience and Mental Health, Ormond College, and, Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Australia

²Neurological Institute, Columbia University, USA

Introduction

The obesity epidemic is well recognized in Western society [1] and is increasing globally [2]. The prevalence of obesity has sometimes been found to be higher among patients with epilepsy, but the problem is less studied in this patient group than in the general population [3]. Prevalence rates of obesity in epilepsy vary across available studies and are likely to be interrelated with activity levels and other health factors. The potential for cardiovascular risk [4] and metabolic syndrome [4, 5], reduced antiepileptic drug (AED) treatment adherence [6], and psychosocial effects of weight gain and obesity [7] all require attention and the mechanisms of weight gain and strategies for prevention of obesity require further study [8]. The problem of obesity in epilepsy requires longitudinal research into risk factors, treatment strategies, weight loss effectiveness, and secondary prevention of complications.

Weight gain is common in association with treatment with some AEDs. It has been long recognized that patients taking sodium valproate may experience weight gain, and more recently the metabolic syndrome has been detected [9]. There can be a rapid weight increase early in therapy and close weight monitoring is recommended [8]. In addition, longer-term monitoring of weight is recommended for patients taking valproate [10]. Weight gain can also be associated with use of carbamazepine, gabapentin, pregabalin, and vigabatrin [6, 11].

Interestingly, the problem of obesity in patients with epilepsy has also been found in AED treatment-naive children, and thus the occurrence of obesity in epilepsy does not rest solely upon a medication side effect [12]. Prevalence is likely to depend on additional factors, including physical activity levels, dietary intake, and the association of obesity with more refractory seizures and AED polytherapy [13].

Whether there are direct neural or hormonal factors [14] linking epilepsy and obesity requires further research [15]. In a retrospective cohort study, after adjustment for age, gender, and smoking status, the incidence rate of seizures was found to be increased in extremely obese patients (BMI ≥40) when compared to those of normal weight [16], with an incidence rate ratio of 1.7 (95% CI 0.7, 3.9), but the difference was not statistically significant. Factors related to obesity in the general population—broadly, the positive imbalance between caloric intake and energy expenditure, the presence of other medical conditions or medications causing weight gain (e.g., thyroid disease, depression, use of glucocorticoid, some antipsychotics), and diet and lifestyle factors—also need to be considered.

The health consequences of obesity are important to assess in patients with epilepsy. For example, extreme obesity and associated cardiovascular disease may raise valid operative risk concerns in patients being assessed for epilepsy surgery. However, a retrospective study of body mass index (BMI) as a predictor did not show an increased perioperative risk or differing seizure outcomes in patients undergoing anterior temporal lobectomy with amygdalohippocampectomy [17]. There was a statistically significant increase in later mortality in the extremely obese group, although data on cause of death were limited [17]. The authors discussed a potential limitation whereby medical prescreening might have prevented surgical management of some patients with extreme obesity and significant cardiovascular comorbidity, meaning this group may have been underrepresented [17]. In addition, the risk of acute myocardial infarction and a subsequent poor outcome may be increased in patients with epilepsy [18]. In some cases, accessibility of MRI or other scanning techniques is limited if the scanner manufacturer's weight safety limits or the machine's physical dimensions are exceeded.

Weight management, and carefully supervised weight reduction (where indicated) after assessment of cardiovascular and exercise injury risks, may improve fitness and well-being and reduce the risk of adverse health consequences of obesity. Weight gain and obesity are important issues for consideration in some patients with epilepsy and should ideally form part of care for epilepsy patients, in both primary care and specialist centers.

Epidemiology

The incidence and prevalence of obesity among patients with epilepsy has received limited study. Reported studies suggest that adults and children with epilepsy have higher rates of obesity. In a population-based sample of over 8000 persons, patients with epilepsy were more likely to be obese (34.1 versus 23.7% rate of obesity in adults with and without epilepsy, respectively) [19]. Likewise, children with newly diagnosed untreated epilepsy had higher BMI Z scores compared to standard Centers for Disease Control and Prevention (CDC) growth charts (p < 0.0001) and a healthy control cohort (p < 0.0002) [12]. Among the epilepsy cohort, 38.6% were overweight or obese. Factors contributing to obesity among patients with epilepsy include physical inactivity, secondary effects on hormones, AED treatment, and comorbid depression.

Pathophysiology

Although obesity is reported commonly in persons with epilepsy, the mechanisms explaining this association are not well defined. The impact of hormonal changes, the effect of AEDs, limited physical activity, and comorbid mood changes may all contribute to the risk of obesity in patients with epilepsy.

Epilepsy and hormonal changes

Alterations in hormonal profiles have been described in patients with epilepsy. Hormonal changes can result in multiple clinical sequelae, including obesity. Abnormalities in sex steroid hormones, thyroid hormones, leptin, and ghrelin are all associated with obesity. These hormones can be affected in patients with epilepsy treated with AEDs.

Reproductive hormones may be altered in men and women with epilepsy. These alterations are likely secondary to a complex relationship between the sex steroid hormone axis, the epilepsy itself, and AED therapy [20, 21]. The concentration and metabolism of estrogen, testosterone, and dehydroepiandrosterone may be modified in persons with epilepsy. These endocrinologic changes can be secondary to epilepsy itself. In those with temporal-lobe epilepsy (TLE), extensive connections between limbic structures and the hypothalamus and pituitary may cause changes in sex steroid hormones. Interestingly, in a cohort of women with partial epilepsy, free estradiol and progesterone were more significantly affected in those with more frequent seizures, supporting the notion that e...

Table of contents

• Cover
• Title Page
• Copyright
• Dedication
• List of contributors
• Preface
• Section I: Quality of life and the interictal state in epilepsy
• Section II: Cognition and epilepsy
• Section III: Adverse effects of epilepsy therapies
• Section IV: Mood state, psychiatric comorbidity, and epilepsy
• Section V: General health and epilepsy
• Index
• End User License Agreement