The polymorphism Val158Met in the COMT gene: disrupted dopamine system in fibromyalgia patients?

ABSTRACT: The single-nucleotide polymorphism (SNP) rs4680 in the catechol-O-methyltransferase gene ( COMT ) is a missense variant (Val158Met) associated with altered activity of the COMT enzyme and suggested as a predictive feature for developing some chronic pain conditions. However, there are controversial results on its role in fibromyalgia (FM). Here, the SNP Val158Met was analyzed in 294 FM patients (without comorbidities) and 209 healthy controls (without chronic pain). The concurrent impact of Val158Met genotypes and FM comorbid disorders (depression and sleep impairment) on FM risk were tested. In addition, the genotypic distribution of FM patients in relation to pain intensity was evaluated. The G allele (Val) resulted in being more represented in the FM group (57.8%) compared with the control group (48.8%; P = 0.037). Logistic regression highlighted that having the G/G (Val/Val) homozygous genotype was associated with 2 times higher risk of having FM compared with the A/A (Met/Met) carriers ( P = 0.038), whereas depression and sleep impairment increased FM risk by 12 and 8 times, respectively ( P < 0.001). However, considering only the FM patient group, the A/A homozygous genotype was significantly associated with severe pain intensity ( P = 0.007). This study highlighted associations between the SNP Val158Met and both FM and pain intensity, suggesting a link between dopaminergic dysfunction and vulnerability to chronic pain. Further studies should explore this SNP in FM patients in conjunction with COMT enzymatic activity and other symptoms connected with the dopaminergic system such as depression or sleep impairment.

DNA Methylation Changes in Fibromyalgia Suggest the Role of the Immune-Inflammatory Response and Central Sensitization.

Fibromyalgia (FM) has been explained as a result of gene-environment interactions. The present study aims to verify DNA methylation differences in eleven candidate genome regions previously associated to FM, evaluating DNA methylation patterns as potential disease biomarkers. DNA methylation was analyzed through bisulfite sequencing, comparing 42 FM women and their 42 healthy sisters. The associations between the level of methylation in these regions were further explored through a network analysis. Lastly, a logistic regression model investigated the regions potentially associated with FM, when controlling for sociodemographic variables and depressive symptoms. The analysis highlighted significant differences in the GCSAML region methylation between patients and controls. Moreover, seventeen single CpGs, belonging to other genes, were significantly different, however, only one cytosine related to GCSAML survived the correction for multiple comparisons. The network structure of methylation sites was different for each group; GRM2 methylation represented a central node only for FM patients. Logistic regression revealed that depressive symptoms and DNA methylation in the GRM2 region were significantly associated with FM risk. Our study encourages better exploration of GCSAML and GRM2 functions and their possible role in FM affecting immune, inflammatory response, and central sensitization of pain.

DNA methylation changes in genes involved in inflammation and depression in fibromyalgia: a pilot study.

OBJECTIVES: The present pilot study aims to investigate DNA methylation changes of genes related to fibromyalgia (FM) development and its main comorbid symptoms, including sleep impairment, inflammation, depression and other psychiatric disorders. Epigenetic modifications might trigger or perpetuate complex interplay between pain transduction/transmission, central pain processing and experienced stressors in vulnerable individuals. METHODS: We conducted DNA methylation analysis by targeted bisulfite NGS sequencing testing differential methylation in 112 genomic regions from leukocytes of eight women with FM and their eight healthy sisters as controls. RESULTS: Tests for differentially methylated regions and cytosines brought focus on the GRM2 gene, encoding the metabotropic glutamate receptor2. The slightly increased DNA methylation observed in the GRM2 region of FM patients may confirm the involvement of the glutamate pathway in this pathological condition. Logistic regression highlighted the simultaneous association of methylation levels of depression and inflammation-related genes with FM. CONCLUSIONS: Altogether, the results evidence the glutamate pathway involvement in FM and support the idea that a combination of methylated and unmethylated genes could represent a risk factor to FM or its consequence, more than single genes. Further studies on the identified biomarkers could contribute to unravel the causative underlying FM mechanisms, giving reliable directions to research, improving the diagnosis and effective therapies.

A family-based study to identify genetic biomarkers of fibromyalgia: consideration of patients' subgroups.

OBJECTIVES: Evidence from genome-wide and candidate gene association studies, familial aggregation and linkage analyses demonstrate the genetic contribution to fibromyalgia (FM) disease. This study aimed to identify genetic biomarkers of FM and its related comorbid disorders, by exploring 41 polymorphisms potentially involved in FM pathogenesis in families with at least one patient with FM. METHODS: Core symptoms were assessed, and blood samples collected from 556 patients with FM and 395 healthy relatives. For the genetic study, a final sample of 401 FM patients and 232 healthy controls was selected, discarding patients with concomitant pathologies and controls with chronic pain. A family-based approach using DFAM test (Plink) and SNPs (single nucleotide polymorphisms) combination analyses to compare FM patients vs. controls were first applied. Second, the genotypic distribution of subgroups of FM patients, stratified by severe vs. mild symptoms of pain, depression and sleep impairment, was considered. RESULTS: No evidence of associations with FM per se were detected, using either a family-based approach or SNPs combination analyses. However, considering the subgroups of FM patients, the SNP rs6454674 (CNR1, cannabinoid receptor 1 gene) was found as a potential genetic marker of FM correlated with depression (p<.001). CONCLUSIONS: No significant associations using either the family-based analysis or the SNPs combination tests dissociated FM patients and their healthy relatives. FM patients with and without depression showed a significant difference in the genotypic distribution related to the SNP rs6454674 in the cannabinoid receptor 1 gene (CNR1) indicating that FM is not a homogenous disorder.

Polymorphism rs7214723 in CAMKK1: a new genetic variant associated with cardiovascular diseases.

Cardiovascular diseases (CVDs) are the leading cause of deaths worldwide. CVDs have a complex etiology due to the several factors underlying its development including environment, lifestyle, and genetics. Given the role of calcium signal transduction in several CVDs, we investigated via PCR-restriction fragment length polymorphism (RFLP) the single nucleotide polymorphism (SNP) rs7214723 within the calcium/calmodulin-dependent kinase kinase 1 (CAMKK1) gene coding for the Ca2+/calmodulin-dependent protein kinase kinase I. The variant rs7214723 causes E375G substitution within the kinase domain of CAMKK1. A cross-sectional study was conducted on 300 cardiac patients. RFLP-PCR technique was applied, and statistical analysis was performed to evaluate genotypic and allelic frequencies and to identify an association between SNP and risk of developing specific CVD. Genotype and allele frequencies for rs7214723 were statistically different between cardiopathic and several European reference populations. A logistic regression analysis adjusted for gender, age, diabetes, hypertension, BMI and previous history of malignancy was applied on cardiopathic genotypic data and no association was found between rs7214723 polymorphism and risk of developing specific coronary artery disease (CAD) and aortic stenosis (AS). These results suggest the potential role of rs7214723 in CVD susceptibility as a possible genetic biomarker.

Genetic and Environmental Risk Factors for Cannabis Use: Preliminary Results for the Role of Parental Care Perception.

BACKGROUND: Vulnerability to cannabis use (CU) initiation and problematic use have been shown to be affected by both genetic and environmental factors, with still inconclusive and uncertain evidence. OBJECTIVE: Aim of the present study was to investigate the possible interplay between gene polymorphisms and psychosocial conditions in CU susceptibility. METHODS: Ninety-two cannabis users and ninety-three controls have been included in the study. Exclusion criteria were serious mental health disorders and severe somatic disorders, use of other drugs and alcohol abuse; control subjects were not screened to remove Reward Deficiency Syndrome (RDS) behaviors. A candidate gene association study was performed, including variants related to dopaminergic and endocannabinoids pathways. Adverse childhood experiences and quality of parental care have been retrospectively explored utilizing ACES (Adverse Children Experience Scale), CECA-q (Child Experience of Care and Abuse Questionnaire), PBI (Parental Bonding Instrument). RESULTS: Our findings evidenced a significant association between rs1800497 Taq1A of ANKK1 gene and CU. Parental care was found to be protective factor, with emotional and physical neglect specifically influencing CU. Gender also played a role in CU, with males smoking more than females. However, when tested together genotypes and psychosocial variables, the significance of observed genetic differences disappeared. CONCLUSIONS: Our results confirm a significant role of Taq1A polymorphism in CU vulnerability. A primary role of environmental factors in mediating genetic risk has been highlighted: parental care could be considered the main target to design early prevention programs and strategies.

Co-occurring Attention Deficit Hyperactivity Disorder symptoms in adults affected by heroin dependence: Patients characteristics and treatment needs.

Attention Deficit Hyperactivity Disorder (ADHD) is a risk for substance use disorders. The aim of this study was to investigate the association between adult ADHD symptoms, opioid use disorder, life dysfunction and co-occurring psychiatric symptoms. 1057 heroin dependent patients on opioid substitution treatment participated in the survey. All patients were screened for adult ADHD symptoms using the Adult ADHD Self-Report Scale (ASRS-v1.1). 19.4% of the patients screened positive for concurrent adult ADHD symptoms status and heroin dependence. Education level was lower among patients with ADHD symptoms, but not significant with respect to non-ADHD patients. Patients with greater ADHD symptoms severity were less likely to be employed. A positive association was observed between ADHD symptoms status and psychiatric symptoms. Patients with ADHD symptoms status were more likely to be smokers. Patients on methadone had a higher rate of ADHD symptoms status compared to buprenorphine. Those individuals prescribed psychoactive drugs were more likely to have ADHD symptoms. In conclusion, high rate of ADHD symptoms was found among heroin dependent patients, particularly those affected by the most severe form of addiction. These individuals had higher rates of unemployment, other co-morbid mental health conditions, heavy tobacco smoking. Additional psychopharmacological interventions targeting ADHD symptoms, other than opioid substitution, is a public health need.

Increased oxytocin levels among abstinent heroin addicts: Association with aggressiveness, psychiatric symptoms and perceived childhood neglect.

A disruption of the oxytocin system seems to affect a variety of brain functions including emotions, mood and social behavior possibly underlying severe social deficits and susceptibility for substance use and mental health disorders. Early life adversity, such as insecure attachment in childhood, has been suggested to influence oxytocin tone contributing to a condition of neurobiological vulnerability. Aim of the present study was to investigate oxytocin serum levels in abstinent heroin addicted patients, in comparison with healthy controls, and the possible correlation with co-occurring psychiatric symptoms, aggressiveness and perception of parental neglect. Eighteen (18) abstinent patients, affected by heroin use disorders, and 18 control subjects, who never used drugs or abused alcohol, were included in the study and submitted to 1) collection of a blood sample for oxytocin assay, 2) Symptoms Check List 90 for psychiatric symptoms evaluation 3) Buss Durkee Hostility Inventory to measure aggressiveness 4) Child Experience of Care and Abuse-Questionnaire to retrospectively test the perception of parental neglect. Heroin exposure extent and heroin dosages were also recorded. Oxytocin serum levels were unexpectedly significantly higher among abstinent patients affected by heroin use disorders and positively correlated with psychiatric symptoms, aggressiveness and mother neglect scores. No correlation was evidenced between oxytocin and heroin exposure extent or dosages. Our findings appear to contradict the simplistic view of oxytocin as a pro-social hormone and confirm previous evidence concerning the peptide levels direct association with aggressive behavior and mood disorders. Considering a more complex mechanism, oxytocin would increase the sensitivity to social salience cues related to contextual or inter-individual factors, promoting pro-sociality in "safe" conditions and, in contrast, inducing more defensive and "anti-social" emotions and behaviors when the social cues are interpreted as "unsafe". This latter condition is often characterizing the clinical history of addicted patients.

Perceived parental care during childhood, ACTH, cortisol and nicotine dependence in the adult.

Studies evidenced the relationship between adverse childhood experiences (ACEs) and tobacco smoking in adulthood. An appropriate parenting style has been found to be associated with children's less frequent tobacco consumption. Hypothalamus-pituitary-adrenal (HPA) axis hyperactivity could represent the potential link between ACEs, mood disorders and smoking susceptibility. We studied a sample of 50 male smokers, affected by nicotine dependence and 50 controls who never smoked. Self-reported retrospective perception of neglect (Child Experience of Care and Abuse: CECA-Q questionnaire), age of smoking onset, number of cigarette/day, psychiatric symptoms (Symptoms Check List 90 scale: SCL 90) and basal level of ACTH and cortisol have been evaluated. Total SCL-90 scores, CECA-Q values and cortisol plasma level were significantly higher among smokers. Cortisol and ACTH values showed a significant direct correlation with CECA-Q and SCL90 total score and an inverse significant correlation with the age of smoking. Cortisol and ACTH did not correlate with the number of cigarette smoked. Once controlled for SCL90 and CECA-Q with multiple regression measures, the association between smoking and hormone levels reversed, suggesting that increased cortisol and ACTH basal levels were attributable to preexisting conditions such as early-life exposure to emotional neglect, psychological problems and a predisposition to addictive behavior.

Sexual Dysfunction in Men Receiving Methadone Maintenance Treatment: Clinical History and Psychobiological Correlates.

A variety of studies evidenced a relationship between drug use disorders and sexual dysfunction. In particular, heroin and opioid agonist medications to treat heroin dependence have been found to be associated with erectile dysfunction and reduced libido. Controversial findings also indicate the possibility of factors other than the pharmacological effects of opioid drugs concurring to sexual dysfunction. With the present study, we investigated the link between sexual dysfunction and long-term exposure to opioid receptor stimulation (heroin dependence, methadone maintenance treatment, methadone dosage), the potentially related hormonal changes reflecting hypothalamus-pituitary-gonadal axis function and prolactin (PRL) pituitary release, the role of adverse childhood experiences in the clinical history and the concomitant symptoms of comorbid mental health disorders in contributing to sexual problems. Forty male patients participating in a long-term methadone treatment program were included in the present study and compared with 40 healthy control subjects who never used drugs nor abused alcohol. All patients and controls were submitted to the Arizona Sexual Experiences Scale (ASEX), Child Experiences of Care and Abuse-Questionnaire (CECA-Q) and the Symptom Check List-90 Scale. A blood sample for testosterone and PRL assays was collected. Methadone dosages were recorded among heroin-dependent patients on maintenance treatment. Methadone patients scored significantly higher than controls on the 5-item rating ASEX scale, on CECA-Q and on Symptoms Check List 90 (SCL 90) scale. Testosterone plasma levels were significantly lower and PRL levels significantly higher in methadone patients with respect to the healthy control group. ASEX scores reflecting sexual dysfunction were directly and significantly correlated with CECA-Q neglect scores and SCL 90 psychiatric symptoms total score. The linear regression model, when applied only to addicted patients, showed that methadone dosages were not significantly correlated with sexual dysfunction scores except for 'erectile dysfunction', for which an inverse association was evidenced. Testosterone values showed a significant inverse correlation with ASEX sexual dysfunction scores, CECA-Q neglect scores and psychiatric symptom at SCL 90 among methadone patients. PRL levels were directly and significantly correlated with sexual dysfunction scores, psychiatric symptoms at SCL 90 and CECA-Q neglect scores. Both testosterone and PRL did not correlate with methadone dosages. The present findings appear to support the view of childhood adversities and comorbid psychiatric symptoms contributing to sexual dysfunction and related hormonal changes among methadone patients, challenging the assumption that attributes sexual problems entirely to the direct pharmacological effects of opioid agonist medications.

Association between gene variants and response to buprenorphine maintenance treatment.

A variety of studies were addressed to differentiate responders and non-responders to substitution treatment among heroin dependent patients, without conclusive findings. In particular, preliminary pharmacogenetic findings have been reported to predict treatment effectiveness in mental health and substance use disorders. Aim of the present study was to investigate the possible association of buprenorphine (BUP) treatment outcome with gene variants that may affect kappa-opioid receptors and dopamine system function. One hundred and seven heroin addicts (West European, Caucasians) who underwent buprenorphine maintenance treatment were genotyped and classified into two groups (A and B) on the basis of treatment outcome. Non-responders to buprenorphine (group B) have been identified taking into account early drop out, continuous use of heroin, severe behavioral or psychiatric problems, misbehavior and diversion during the 6 months treatment period. No difference was evidenced between responders and non-responders to BUP in the frequency of kappa opioid receptor (OPRK1) 36G>T SNP. The frequency of dopamine transporter (DAT) gene polymorphism (SLC6A3/DAT1), allele 10, was evidently much higher in "non-responder" than in "responder" individuals (64.9% vs. 55.93%) whereas the frequency of the category of other alleles (6, 7 and 11) was higher in responder than in non-responder individuals (11.02% vs. 2.13% respectively). On one hand, the hypothesis that possible gene-related changes in kappa-opioid receptor could consistently affect buprenorphine pharmacological action and clinical effectiveness was not confirmed in our study, at least in relation to the single nucleotide polymorphism 36G>T. On the other hand, the possibility that gene-related dopamine changes could have reduced BUP effectiveness and impaired maintenance treatment outcome was cautiously supported by our findings. DAT1 gene variants such as allele 10, previously reported in association with personality and behavioral problems, would have influenced the effects of BUP-induced dopamine release, modulated through mu and kappa opioid receptors, and probably the related reinforcing capacity of the drug.

Adrenocorticotropic hormone and cortisol plasma levels directly correlate with childhood neglect and depression measures in addicted patients.

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has been reported to be involved in vulnerability to alcohol and drug dependence in humans, possibly underlying both addictive behaviour and depression susceptibility. The aim of the present study was to investigate the possible interactions between childhood adverse experiences, depressive symptoms and HPA axis function in addicted patients, in comparison with healthy control. Eighty-two abstinent heroin or cocaine dependent patients and 44 normal controls, matched for age and sex, completed the symptoms Check List-90 (SCL-90), measuring depressive symptoms, and the Childhood Experience of Care and Abuse Questionnaire. Blood samples were collected to determine adrenocorticotropic hormone (ACTH) and cortisol basal plasma levels at 8:00 and 8:30 a.m. Addicted individuals showed significantly higher neglect and depression scores and ACTH-cortisol plasma levels respect to control subjects. Depression scores at SCL-90 in addicted patients positively correlated with plasma ACTH and cortisol values. In turn, plasma ACTH levels were directly associated with childhood neglect measures, reaching statistical significance with 'mother-neglect' scores. Plasma cortisol levels were related to 'father antipathy' among cocaine addicts. These findings suggest the possibility that childhood experience of neglect and poor parent-child attachment may have a persistent effect on HPA axis function as an adult, partially contributing, together with genetic factors and other environmental conditions, to both depressive traits and substance abuse neurobiological vulnerability.