Comparison of endocannabinoids levels, FAAH gene polymorphisms, and appetite regulatory substances in women with and without binge eating disorder: a cross- sectional study
Introduction
Global reports indicate that overweight and obesity are 2 of the most important public health problems in all age groups throughout the world [1]. Although obesity is a multifactorial metabolic disorder, its major reasons have not been well recognized yet. However, the unusual motivation leading to eating beyond satiety is still a critical problem that usually results in obesity [2].
Obesity and its complications are regarded as the medical comorbidities that are frequently seen in binge eating disorder (BED) [3]. Among eating disorders, BED is known as the most common one, which is associated with repetitive periods of excessive food intake and loss of control but without purging behaviors [4]. In the Appendix of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, of the American Psychiatric Association, BED falls into the Eating Disorder Not Otherwise Specified category [5]. In individuals with obesity, BED is overrepresented and might be considered as one of the contributing factors to their weight gain [6]. Throughout the life cycle, the BED prevalence rate in community samples of individuals 18 years and older is 3.5%, with the rates much higher (6.2%) in women between 18 and 24 years of age. It also seems to be more prevalent among overweight and obese samples (30%) compared to the general population [7]. The present increase in obesity and recent BED rate that likely contributes to obesity is an important factor that must be understood [8].
It is generally believed that eating disorders have a multifactorial and complex etiopathogenesis, with both psychosocial and biological factors involved [9]. The endogenous cannabinoids (eg, anandamide [AEA] and 2-arachidonoyl glycerol [2-AG]) have been shown to control food intake in both humans and animals, in addition to modifying eating behavior, which demonstrates that endocannabinoid system alterations could be engaged in the eating disorders pathophysiology [10,11]. Also, polymorphisms of the fatty acid amid hydrolase (FAAH) gene, the main deactivating enzyme of anadamide, have previously been shown to increase the biological susceptibility of eating disorders [12,13]. In fact, the FAAH gene disruption significantly raises the levels of endogenous fatty acid amides in the central nervous system, which result in appetite modulation.
Moreover, based on the reported relationship of the endocannabinoids with endogenous leptin and because of the previously explained effects of long-term food deficit on these factors in brain, it seems reasonable that leptin is also involved in the EDs pathophysiology [14,15].
In different studies, a higher prevalence of BED has been documented in overweight and young patients with type 2 diabetes [16,17]. Additionally, BED is associated with insufficient glycemic control as well as more adverse diabetic complications among adolescents with type 1 diabetes [1]. Obesity-induced insulin resistance can cause changes in the suppressive effects of insulin on brain reward processing regions, which consequently result in overeating and subsequent EDs [18,19].
Approximately 20 years ago, a group of neuropeptides, known as orexins (orexin-A and orexin-B), was discovered within the lateral hypothalamus [20]. Accordingly, orexins have been shown to have a positive role in food intake, mainly in palatable foods intake. Consequently, it is highly possible that these neurons engage in binge eating that includes a hedonic control of food intake [21].
To manage binge eating behavior efficiently, it is required to further examine the substances and genes associated with this behavior. In this study, we assessed the hypothesis that the levels of endocannabinoids, FAAH gene polymorphisms, and appetite regulatory substances would be different in women who are overweight and obese with BEDs. Our specific objectives were to evaluate the BED prevalence in the participants included and to compare the levels of AEA, 2-AG, leptin, insulin, orexin A, and the genotypes of FAAH gene in women with and without BED.
Section snippets
Ethics statement
The Ethics Committee of Tabriz University of Medical Science (IR.TBZMED.REC.1396.620) approved the study protocol, and the study was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki. Written informed consent was obtained from all participants prior to their inclusion into the study.
Study design and participants
This study was carried out as a cross- sectional study on 180 overweight and obese premenopausal women in Tabriz, Iran, from October 2017 to February 2018. The sample
Participants
The characteristics of the participants are shown in Table 1. A total of 180 women took part in the study. The mean age of the sample was 34.2 ± 8.27 years, and the mean of their BMI was 32.5 ± 3.73 kg/m2. Approximately more than half of the individuals had low levels of activity (54.4%), and the rest were moderately active (39.4%) or highly active (6.1%).
Assessment of the BED
The frequency of BED among female participants was as follows: nonbingeing, less than 17; moderate bingeing, 18-26; and severe bingeing, 27
Discussion
The current study investigated and compared the endocannabinoids levels, FAAH gene polymorphisms, and appetite regulatory substances in women with and without BED. Moreover, in this study, the group of obese patients showed a higher BED score compared to overweight women, which supports the finding that binge eating behavior is usually associated with obesity or vice versa. Consistent with earlier results by other researchers, BED individuals consume more total energy than non-BED ones, which
Acknowledgment
The authors wish to thank the participants for their cooperation, time, and patience and Tabriz University of Medical Sciences for the financial support. The authors declare that there is no conflict of interest. This work was supported by Tabriz University of Medical Sciences. The results of this paper are from Neda Lotfi's PhD thesis. NLY and RM were the major contributors of the manuscript, designed the research project, agreed for all aspects of the work, and wrote the manuscript. SA
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2021, AppetiteCitation Excerpt :Thirteen studies have examined leptin in relation to LOC eating, subclinical binge-eating, BED, disinhibition, uncontrolled eating, and food addiction, and 5 studies identified significantly higher levels of leptin in these eating behaviors. In detail, 4 studies found significantly higher levels of leptin in adolescents with LOC eating (Miller et al., 2014), bariatric candidates or women with BED (Adami et al., 2002; Yagin, Aliasgari, Alizadeh, Aliasgharzadeh, & Mahdavi, 2020), and adolescents with food addiction (Peters et al., 2018) relative to controls. Among these 4 studies, 1 study also reported that higher levels of leptin predicted higher odds of binge-eating behaviors among women with BED (Yagin et al., 2020), and another study demonstrated a positive association between leptin and disinhibition among bariatric candidates (regardless of BED diagnosis) (Adami et al., 2002).
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Both authors contributed equally to this manuscript.