Genetic variants in dopamine pathways affect personality dimensions displayed by patients with eating disorders

Association of genetic variation in the leptin-melanocortin system with drive for thinness in patients with eating disorders: A pilot study

We aimed to investigate whether genetic variants in the leptin-melanocortin system involved in anorexigenic signaling influence personality dimensions and psychopathological symptoms in eating disorders (ED) patients. The population consisted of 309 ED patients [221 with anorexia nervosa (AN) and 88 with bulimia nervosa (BN)] and 396 healthy controls. Patients underwent psychometric assessment using the Eating Disorders Inventory Test-2 (EDI-2) and the Symptom Checklist 90 Revised (SCL-90R) questionnaires. Fourteen tag-SNPs in the LEP, POMC, and MC4R genes, were determined. Drive for thinness (DT) was significantly affected by genetic variability. After correction for multiple testing, regression models showed that AN patients carrying the LEP rs11761556 CC variant genotype scored higher in this scale than AA/CA carriers did [mean difference = 4.43 (2.18-6.68), p < 0.001], although the significance was restrained to the restrictive subtype [4.92 (2.00-7.83), p = 0.001]. BN patients with the LEP rs10954173 AA genotype displayed lower scores [-8.7 (-12.31--3.91); p < 0.001]. Finally, gene-gene interaction analyses revealed two SNP pairs associated with body-mass index in AN patients (LEPrs3828942-POMCrs1009388, p < 0.001 and LEP rs11763517-POMCrs1009388, p = 0.002). Regarding DT scores, the POMCrs6545975-LEP11763517 SNP pair showed the strongest effect (p < 0.001) in AN. Genetic variants in the leptin-melanocortin system, may interact to influence personality dimensions in ED patients, which highlights the importance of considering genetic factors in the pathophysiology of these disorders.

Personality and Psychoneuroimmunology: A Systems Biology Perspective

Research in psychoneuroimmunology (PNI) underscores the intricate connections within the "whole mind-body system." Personality plays a pivotal role, with specific traits linked to stress influencing neural behavior and psychophysiological disorders. Gene expression networks associated with personality affect neuronal plasticity, epigenetic processes, and adaptive behaviors, highlighting the importance of systems biology mechanisms. Systemic inflammation correlates with key personality traits. Understanding the roles of inflammatory and oxidative biomarkers in personality traits and disorders can help identify diagnostic and therapeutic targets for various diseases. Neurobiological features contribute to our understanding of personality disorders and related conditions. Personality traits are linked to distributed neuroendocrine networks, particularly the hypothalamic-pituitary-adrenal (HPA) axis, rather than localized brain areas. Correlations have also been identified between personality traits and thyroid hormones. Disrupted hypothalamic-pituitary-thyroid (HPT) axis functions may be associated with disease severity, depression, and distress, highlighting the need for comprehensive endocrinological and psychopathological evaluations. The gut-brain axis influences personality traits, emotions, stress, and social behaviors. Altered gut microbiota is common in psychiatric conditions, suggesting potential treatments targeting the microbiota. Chronic stress impacts cognitive functions and correlates with personality and mental health, emphasizing the need for comprehensive, multi-dimensional patient profiles for effective prevention and therapy. A biopsychosocial model integrating personality traits will advance personalized and systems medicine.

Association of OPRD1 Gene Variants with Changes in Body Weight and Psychometric Indicators in Patients with Eating Disorders

Objectives: This study aimed to investigate whether genetic variations in the OPRD1 gene affect psychopathological symptoms and personality dimensions in eating disorders (ED) patients and/or contribute to ED risk. Methods: The study involved 221 female patients with anorexia nervosa (AN), 88 with bulimia nervosa (BN), and 396 controls. Sixteen tag-single nucleotide polymorphisms (SNPs) in OPRD1 were identified. Psychometric evaluations were conducted using the Symptom Checklist 90 Revised (SCL-90R) and the Eating Disorders Inventory Test-2 (EDI-2). p-values obtained by regression models were corrected for multiple testing by the False Discovery Rate (FDR) method. Results: In AN patients, genotypes rs204077TT and rs169450TT were linked to lower body-mass index (BMI) values (FDR-q = 0.035 and 0.017, respectively), as was rs2234918 in a log-additive model (BMI: 18.0 ± 0.28, 17.22 ± 0.18 and 16.59 ± 0.39 for TT, TC and CC carriers, FDR-q = 0.012). Additionally, AN patients carrying the rs72665504AA genotype had higher scores in interpersonal distrust (FDR-q = 0.030), whilst BN carriers of rs513269TT and rs2873795TT showed lower scores in ineffectiveness (FDR-q = 0.041 and FDR-q = 0.021). In the AN group, BMI correlated with variability in a distal haplotype (rs508448/rs204077/rs223491, FDR-q = 0.028), which was also associated with the global positive symptom total (PST) index of SCL-90R (FDR-q = 0.048). Associations were more noticeable in BN patients; again, the distal region of the gene was linked to EDI-2 total scores (FDR-q = 0.004-0.048 for the four last haplotypes) and two global SCL-90R indices (GSI: FDR-q = 0.011 and positive symptom distress index (PSDI): FDR-q = 0.003 for the last s204077/rs2234918/rs169450 combination). No associations with ED risk were observed. Conclusions: Genetic variation in the OPRD1 gene, particularly in its distal region, is associated with BMI and psychopathological comorbidities in ED patients.

Relationship of Genetic Polymorphisms and Microbial Composition with Binge Eating Disorder: A Systematic Review

Humans are the result of an evolutionary process, and because of this, many biological processes are interconnected with each other. The intestine-brain axis consists of an intricately connected neuronal-neuroendocrine circuit that regulates the sensation of hunger and satiety. Genetic variations and the consumption of unnatural diets (ultra-processed foods, high contents of sugars, etc.) can override this circuit and cause addiction to certain foods and/or the inability to feel satiety in certain situations. The patients who come to consultations (mainly psychology or nutrition) in an attempt to resolve this problem sometimes fail, which leads to them looking for new strategies based on biological predisposition. This investigation aims to evaluate the genetic studies regarding the microbiota carried out in the last 12 years in humans to try to determine which genes and microbes that have been recently studied are related to patients diagnosed with binge eating disorder or compulsive eating (presenting obesity or not). The protocol followed the PRISMA statement, and the following databases were searched from 2012 until the present day: PubMed, PsycINFO, SCOPUS, and Web of Science. Twenty-four international articles were analyzed, including cross-sectional or exploratory studies; five of them referred to the microbial composition, and in nineteen, the existence of genetic polymorphisms present in binge eating disorder or in compulsive eating could be observed: DRD2, OPRM1, COMT, MC4R, BNDF, FTO, SLC6A3, GHRL, CARTPT, MCHR2, and LRP11. Even though there is still much to investigate on the subject, it must be highlighted that, in the last 4 years, a two-fold increase has been observed in potential markers and in studies related to the matter, also highlighting the importance of different analyses in relation to psychosocial factors and their interaction with the genetic and microbial factors, for which research on the matter must be continued.

Genetic polymorphisms and their association with neurobiological and psychological factors in anorexia nervosa: a systematic review

Background and aims

Anorexia nervosa (AN) is a complex neuropsychiatric disorder. This systematic review synthesizes evidence from diverse studies to assess and investigate the association between gene polymorphisms and psychological and neurobiological factors in patients with AN.

Methods

A systematic search across PubMed, PsycINFO, Scopus, and Web of Science databases, along with manual searching, was conducted. The review protocol was approved by PROSPERO (CRD42023452548). Out of 1,250 articles, 11 met the inclusion criteria. The quality of eligible articles was assessed using the Newcastle-Ottawa Scale (NOS) tool. The systematic review followed the PRISMA guidelines.

Results

The serotoninergic system, particularly the 5-HTTLPR polymorphism, is consistently linked to altered connectivity in the ventral attention network, impaired inhibitory control, and increased susceptibility to AN. The 5-HTTLPR polymorphism affects reward processing, motivation, reasoning, working memory, inhibition, and outcome prediction in patients with AN. The dopaminergic system, involving genes like COMT, DRD2, DRD3, and DAT1, regulates reward, motivation, and decision-making. Genetic variations in these dopaminergic genes are associated with psychological manifestations and clinical severity in patients with AN. Across populations, the Val66Met polymorphism in the BDNF gene influences personality traits, eating behaviors, and emotional responses. Genes like OXTR, TFAP2B, and KCTD15 are linked to social cognition, emotional processing, body image concerns, and personality dimensions in patients with AN.

Conclusion

There was an association linking multiple genes to the susceptibly and/or severity of AN. This genetic factor contributes to the complexity of AN and leads to higher diversity of its clinical presentation. Therefore, conducting more extensive research to elucidate the underlying mechanisms of anorexia nervosa pathology is imperative for advancing our understanding and potentially developing targeted therapeutic interventions for the disorder.Systematic review registration: [https://clinicaltrials.gov/], identifier [CRD42023452548].

Gene variants in eating disorders. Focus on anorexia nervosa, bulimia nervosa, and binge-eating disorder

Eating disorders such as anorexia nervosa, bulimia nervosa and binge-eating disorder, have a deep social impact, concluding with death in cases of severe disease. Eating disorders affect up to 5% of the population in the industrialized countries, but probably the phenomenon is under-detection and under-diagnosis. Eating disorders are multifactorial disorders, resulting from the interaction between environmental triggers, psychological factors, but there is also a strong genetic component. In fact, genetic factors predispose for approximately 33-84% to anorexia nervosa, 28-83% to bulimia nervosa, and 41-57% to binge eating disorder. Twins and family studies have provided an unassailable proof on the heritability of these disorders. Other types of genetic studies, including genome-wide association studies, whole genome sequencing and linkage analysis, allowed to identify the genes and their variants associated with eating disorders and moreover global collaborative efforts have led to delineate the etiology of these disorders. Next Generation Sequencing technologies can be considered as an ideal diagnostic approach to identify not only the common variants, such as single nucleotide polymorphism, but also rare variants. Here we summarize the present knowledge on the molecular etiology and genetic determinants of eating disorders including serotonergic genes, dopaminergic genes, opioid genes, appetite regulation genes, endocannabinoid genes and vitamin D3.

Prenatal Effects of Nicotine on Obesity Risks: A Narrative Review

Nicotine usage by mothers throughout pregnancy has been observed to relate to numerous deleterious effects in children, especially relating to obesity. Children who have prenatally been exposed to nicotine tend to have lower birth weights, with an elevated risk of becoming overweight throughout development and into their adolescent and adult life. There are numerous theories as to how this occurs: catch-up growth theory, thrifty phenotype theory, neurotransmitter or endocrine imbalances theory, and a more recent examination on the genetic factors relating to obesity risk. In addition to the negative effect on bodyweight and BMI, individuals with obesity may also suffer from numerous comorbidities involving metabolic disease. These may include type 1 and 2 diabetes, high cholesterol levels, and liver disease. Predisposition for obesity with nicotine usage may also be associated with genetic risk alleles for obesity, such as the DRD2 A1 variant. This is important for prenatally nicotine-exposed individuals as an opportunity to provide early prevention and intervention of obesity-related risks.

A literature review of dopamine in binge eating

OBJECTIVE

Binge eating, a core diagnostic symptom in binge eating disorder and bulimia nervosa, increases the risk of multiple physiological and psychiatric disorders. The neurotransmitter dopamine is involved in food craving, decision making, executive functioning, and impulsivity personality trait; all of which contribute to the development and maintenance of binge eating. The objective of this paper is to review the associations of dopamine levels/activities, dopamine regulator (e.g., dopamine transporter, degrading enzymes) levels/activities, and dopamine receptor availability/affinity with binge eating.

METHODS

A literature search was conducted in PubMed and PsycINFO to obtain human and animal studies published since 2010.

RESULTS

A total of 31 studies (25 human, six animal) were included. Among the human studies, there were 12 case-control studies, eight randomized controlled trials, and five cross-sectional studies. Studies used neuroimaging (e.g., positron emission tomography), genetic, and pharmacological (e.g., dopamine transporter inhibitor) techniques to describe or compare dopamine levels/activities, dopamine transporter levels/activities, dopamine degrading enzyme (e.g., catechol-O-methyltransferase) levels/activities, and dopamine receptor (e.g., D1, D2) availability/affinity among participants with and without binge eating. Most human and animal studies supported an altered dopaminergic state in binge eating (26/31, 83.9%); however, results were divergent regarding whether the altered state was hyperdopaminergic (9/26, 34.6%) or hypodopaminergic (17/26, 65.4%). The mixed findings may be partially explained by the variability in sample characteristics, study design, diagnosis criteria, and neuroimaging/genetic/pharmacological techniques used. However, it is possible that instead of being mutually exclusive, the hyperdopaminergic and hypodopaminergic state may co-exist, but in different stages of binge eating or in different individual genotypes.

CONCLUSIONS

For future studies to clarify the inconsistent findings, a homogenous sample that controls for confounders that may influence dopamine levels (e.g., psychiatric diseases) is preferable. Longitudinal studies are needed to evaluate whether the hyper- and hypo-dopaminergic states co-exist in different stages of binge eating or co-exist in individual phenotypes. Binge eating is characterized by eating a large amount of food in a short time and a feeling of difficulty to stop while eating. Binge eating is the defining symptom of binge eating disorder and bulimia nervosa, both of which are associated with serious health consequences. Studies have identified several psychological risk factors of binge eating, including a strong desire for food, impaired cognitive skills, and distinct personality traits (e.g., quick action without careful thinking). However, the physiological markers of binge eating remain unclear. Dopamine is a neurotransmitter that is heavily involved in feeding behavior, human motivation, cognitive ability, and personality. Therefore, dopamine is believed to play a critical role in binge eating. This review synthesized study findings related to the levels and activities of dopamine, dopamine regulators, and dopamine receptors in the context of binge eating. The primary finding is that most studies that used neuroimaging, genetic, or drug techniques found an altered dopaminergic state related to binge eating. However, the literature is inconsistent concerning the direction of the alteration. Considering the mixed findings and the limitations in study design, future studies, especially those that include repeated measurements, are needed to clarify the role of dopamine in binge eating.

Variability in the antioxidant MSRA gene affects the psychopathology of patients with anorexia nervosa

The objective is to determine whether variability in the MSRA gene, related to obesity and several psychiatric conditions, may be relevant for psychopathological symptoms common in Anorexia Nervosa (AN) and/or for the susceptibility to the disorder. A total of 629 women (233 AN patients and 396 controls) were genotyped for 14 tag-SNPs. Psychometric evaluation was performed with the EDI-2 and SCL-90R questionnaires. Genetic associations were carried out by logistic regression controlling for age and adjusting for multiple comparisons (FDR method). Two tag-SNPs, rs11249969 and rs81442 (with a pairwise r2 value of 0.41), were associated with the global EDI-2 score, which measures EDI-related psychopathology (adjusted FDR-q = 0.02 and 0.04, respectively). Moreover, rs81442 significantly modulated all the scales of the SCL-90R test that evaluates general psychopathology (FDR-q values ranged from 4.1E-04 to 0.011). A sliding-window analysis using adjacent 3-SNP haplotypes revealed a proximal region of the MSRA gene spanning 187.8 Kbp whose variability deeply affected psychopathological symptoms of the AN patients. Depression was the symptom that showed the strongest association with any of the constructed haplotypes (FDR-q = 3.60E-06). No variants were found to be linked to AN risk or anthropometric parameters in patients or controls. Variability in the MSRA gene locus modulates psychopathology often presented by AN patients.

Variability in cannabinoid receptor genes is associated with psychiatric comorbidities in anorexia nervosa

PURPOSE

The endocannabinoid system plays a key role in eating behavior regulating appetite and reward mechanisms, but the impact of its genetic variability has been scarcely studied in Anorexia Nervosa (AN). We aimed to analyze the association of genetic variants in cannabinoid receptors with the risk for AN and with psychiatric comorbidities that are commonplace in these patients.

METHODS

We screened 221 AN patients and 396 controls for 14 tag-SNPs in the CNR1 and CNR2 genes, coding for cannabinoids receptors CB1 and CB2, respectively. Patients were diagnosed according to DSM-5 criteria and interviewed with the SCL-90R and the EDI-2 inventories to identify AN-coupled and general psychopathology.

RESULTS

None of the tag-SNPs was significantly related to AN risk. However, the rs806369-TT genotype and haplotype rs806368/rs1049353/rs806369 of CNR1 were respectively associated with lower weight (mean difference = - 4.92 kg, FDR-q = 0.044) and BMI (FDR-q = 0.042) in AN patients. CNR1 rs806374-TT and CNR2 rs3003335-AA and rs6658703-GG genotypes correlated with higher scores in the Positive Symptom Distress Index (PSDI, FDR-q = 0.011 and 0.009, respectively). These three genotypes were also linked to increased Hostility in the patients (FDR-q < 0.05). Remarkably, a proximal area of the CNR1 gene locus (positions 88,143,916-88,149,832) correlated with PSDI, Hostility, Asceticism and EDI-2 total scores after correcting by multiple testing (FDR-q < 0.05 in all instances). Finally, significant CNR1/CNR2 epistasis was observed in relation to Hostility (p < 0.01) and Maturity Fears (p < 0.001).

CONCLUSION

The CNR1 and CNR2 genes, coding for cannabinoid receptors, may constitute important loci regarding psychiatric comorbidities in AN patients.

LEVEL III

Evidence obtained from well-designed cohort or case-control analytic studies.

Variants in the Obesity-Linked FTO gene locus modulates psychopathological features of patients with Anorexia Nervosa

Our aim was to determine whether variability in the fat mass obesity (FTO) gene locus, consistently related to obesity, affects the risk of eating disorders (ED) and/or the psychopathology displayed by these patients. We analyzed 26 tag-single nucleotide polymorphisms (SNPs) that capture FTO variability in 352 ED patients [233 with Anorexia Nervosa (AN) and 119 with binge-eating] and 396 controls. Psychopathological symptoms and traits were evaluated by the Eating Disorders Inventory Test 2 (EDI-2) and Symptoms Checklist 90 Revised (SCL-90R) questionnaires. No associations were found for ED risk. The rs7205987 CC genotype correlated with higher scores in all but one of the EDI-2 scales in the AN group. Associations with Bulimia (p = 0.0019) and Interoceptive Awareness (p = 0.00007) retained significance after False Discovery Rate (FDR) correction for multiple testing. A 3-SNP sliding window analysis showed that FTO haplotypes were again highly associated with Interoceptive Awareness (rs9921255/rs6499662/rs7205987 haplotype; FDR-q = 0.04), Bulimia (rs1125338/rs2192872/rs708258; FDR-q = 0.00037), and Maturity Fears (rs708258/rs12599672/rs11076017; FDR-q = 0.041). In addition, a distal region of the gene between rs9924877 (position 53947509) and rs2192872 (54040715) was linked to Anxiety, Depression and Phobic Anxiety in AN patients, with FDR-q values ranging from 0.023 to 0.045. The results suggest that the FTO gene might be an important locus regarding traits and psychopathological symptoms often displayed by AN patients.

A Systematic Review of Genetic Polymorphisms Associated with Binge Eating Disorder

The genetic polymorphisms involved in the physiopathology of binge eating disorder (BED) are currently unclear. This systematic review aims to highlight and summarize the research on polymorphisms that is conducted in the BED. We looked for observational studies where there was a genetic comparison between adults with BED, in some cases also with obesity or overweight, and healthy controls or obesity/overweight without BED. Our protocol was written using PRISMA. It is registered at PROSPERO (identification: CRD42020198645). To identify potentially relevant documents, the following bibliographic databases were searched without a time limit, but until September 2020: PubMed, PsycINFO, Scopus, and Web of Science. In total, 21 articles were included in the qualitative analysis of the systematic review, as they met the eligibility criteria. Within the selected studies, 41 polymorphisms of 17 genes were assessed. Overall, this systematic review provides a list of potentially useful genetic polymorphisms involved in BED: 5-HTTLPR (5-HTT), Taq1A (ANKK1/DRD2), A118G (OPRM1), C957T (DRD2), rs2283265 (DRD2), Val158Met (COMT), rs6198 (GR), Val103Ile (MC4R), Ile251Leu (MC4R), rs6265 (BNDF), and Leu72Met (GHRL). It is important to emphasize that Taq1A is the polymorphism that showed, in two different research groups, the most significant association with BED. The remaining polymorphisms need further evidence to be confirmed.

Early Life Stress and the Onset of Obesity: Proof of MicroRNAs' Involvement Through Modulation of Serotonin and Dopamine Systems' Homeostasis

Healthy persons hold a very complex system for controlling energy homeostasis. The system functions on the interconnected way between the nutritional, endocrine, neural, and epigenetic regulation, which includes the microRNAs (miRNAs). Currently, it is well accepted that experiences of early life stress (ELS) carry modification of the central control of feeding behavior, one of the factors controlling energy homeostasis. Recently, studies give us a clue on the modulation of eating behavior, which is one of the main factors associated with the development of obesity. This clue connected the neural control through the serotonin (5HT) and dopamine (DA) systems with the fine regulation of miRNAs. The first pieces of evidence highlight the presence of the miR-16 in the regulation of the serotonin transporter (SERT) as well as the receptors 1a (5HT1A) and 2a (5HT2A). On the other hand, miR-504 is related to the dopamine receptor D2 (DRD2). As our knowledge advance, we expected to discover other important pathways for the regulation of the energy homeostasis. As both neurotransmission systems and miRNAs seem to be sensible to ELS, the aim of this review is to bring new insight about the involvement of miRNAs with a central role in the control of eating behavior focusing on the influences of ELS and regulation of neurotransmission systems.