A Novel Interaction between Tryptophan Hydroxylase 2 (TPH2) Gene Polymorphism (rs4570625) and BDNF Val66Met Predicts a High-Risk Emotional Phenotype in Healthy Subjects

Prevalence of Common Alleles of Some Stress Resilience Genes among Adolescents Born in Different Periods Relative to the Socioeconomic Crisis of the 1990s in Russia

Social stress is common among people and is considered one of the causes of the declining birth rate. Predisposition to stress and stress-induced disorders is largely determined genetically. We hypothesized that due to differences in stress resistance, carriers of different genetic variants of genes associated with stress resilience and stress-induced diseases may have dissimilar numbers of offspring under conditions of long-term social stress. To test this hypothesis, a comparative analysis of frequencies of seven common polymorphic regions [exon 3 variable number of tandem repeats (VNTR) of the DRD4 gene, rs4680 of COMT, STin2 VNTR and the 5-HTTLPR (rs774676466) insertion/deletion polymorphism of SLC6A4, rs4570625 of TPH2, rs6265 of BDNF, and rs258747 of NR3C1] was performed on standardized groups of randomly selected adolescents born before, during, and after severe socioeconomic deprivation (the crisis of the 1990s in Russia). There were significant differences in frequencies of "long" alleles of the DRD4 gene (p = 0.020, χ² = 5.492) and rs4680 (p = 0.022, χ² = 5.289) in the "crisis" group as compared to the combined "noncrisis" population. It is possible that the dopaminergic system had an impact on the successful adaptation of a person to social stress.

Physical Exercise, a Potential Non-Pharmacological Intervention for Attenuating Neuroinflammation and Cognitive Decline in Alzheimer's Disease Patients

This narrative review summarises the evidence for considering physical exercise (PE) as a non-pharmacological intervention for delaying cognitive decline in patients with Alzheimer’s disease (AD) not only by improving cardiovascular fitness but also by attenuating neuroinflammation. Ageing is the most important risk factor for AD. A hallmark of the ageing process is a systemic low-grade chronic inflammation that also contributes to neuroinflammation. Neuroinflammation is associated with AD, Parkinson’s disease, late-onset epilepsy, amyotrophic lateral sclerosis and anxiety disorders. Pharmacological treatment of AD is currently limited to mitigating the symptoms and attenuating progression of the disease. AD animal model studies and human studies on patients with a clinical diagnosis of different stages of AD have concluded that PE attenuates cognitive decline not only by improving cardiovascular fitness but possibly also by attenuating neuroinflammation. Therefore, low-grade chronic inflammation and neuroinflammation should be considered potential modifiable risk factors for AD that can be attenuated by PE. This opens the possibility for personalised attenuation of neuroinflammation that could also have important health benefits for patients with other inflammation associated brain disorders (i.e., Parkinson’s disease, late-onset epilepsy, amyotrophic lateral sclerosis and anxiety disorders). In summary, life-long, regular, structured PE should be considered as a supplemental intervention for attenuating the progression of AD in human. Further studies in human are necessary to develop optimal, personalised protocols, adapted to the progression of AD and the individual’s mental and physical limitations, to take full advantage of the beneficial effects of PE that include improved cardiovascular fitness, attenuated systemic inflammation and neuroinflammation, stimulated brain Aβ peptides brain catabolism and brain clearance.

Serotonin-Related Functional Genetic Variants Affect the Occurrence of Psychiatric and Motor Adverse Events of Dopaminergic Treatment in Parkinson’s Disease: A Retrospective Cohort Study

The serotonergic system is important in Parkinson’s disease (PD) pathogenesis as it can take over dopamine production after a large portion of dopaminergic neurons is lost through neurodegeneration. The aim of this study was to evaluate the effect of genetic variability of serotonergic genes on the occurrence of motor complications and psychiatric adverse events (AE) due to dopaminergic treatment. We enrolled 231 patients and their clinical data were collected. Genotyping was performed for eight genetic variants. Logistic regression was used for analysis. Carriers of the HTR1A rs6295 GC genotype (OR = 2.58; 95% CI = 1.15–5.78; p = 0.021), TPH2 rs4290270 AA genotype (OR = 2.78; 95% CI = 1.08–7.03; p = 0.034), and at least one TPH2 rs4570625 T allele (OR = 1.86; 95% CI = 1.00–3.44; p = 0.047) had increased risk for visual hallucinations (VH). Additionally, carriers of at least one SLC6A4 5-HTTPLR rs25531 S (OR = 0.52; 95% CI = 0.28–0.96; p = 0.037) or at least one L_G allele (OR = 0.37; 95% CI = 0.14–0.97; p = 0.044) had a decreased chance for VH. Constructed haplotypes of the TPH2 showed increased risk for VH (OR = 1.94; 95% CI = 1.06–3.55; p = 0.032) and impulse control disorders (OR = 5.20; 95% CI = 1.86–14.50; p = 0.002). Finally, individual gene–gene interactions showed decreased odds for the development of motor AE. Our findings suggest that the serotonergic pathway may play an important role in the development of AE resulting from dopaminergic treatment.

The relationship between occupational stress, musculoskeletal disorders and the mental health of coal miners: The interaction between BDNF gene, TPH2 gene polymorphism and the environment

OBJECTIVE

Mental disorders are prevalent among the population and seriously endanger people's working ability as well as their physical and mental health. This study employed stratified cluster random sampling to examine occupational stress, musculoskeletal disorders (MSDs) and the mental health status of 1675 coal miners in Xinjiang.

METHODS

A cross-sectional investigation was carried out, and BDNF (rs6265, rs10835210) gene polymorphism and TPH2(rs4570625, rs4131347) gene polymorphism were identified in 30% of the study's participants. This study aimed to analyze the relationship between mental disorders, occupational stress and MSDs, and to explore the role of gene-gene and gene-environment interactions in respect to the incidence of psychological disorders. On this basis, the risk prediction model of mental disorders was constructed.

RESULTS

The study identified the following risk factors for mental disorders among coal miners: Female, age, four shifts, coal miners, college education or above, single, occupational stress, and MSDs. MSDs, BDNF gene (rs6265) and TPH2 gene (rs4570625) are directly related to mental disorders, and interactions were found between MSDs and BDNF gene (rs6265),TPH2 gene (rs4570625), affecting the incidence of mental disorders. The Bayesian network model of mental disorders showed that MSDs, educational level, TPH2 gene (rs4570625) and marital status had a higher influence on mental disorders. Monthly income and educational level can indirectly affect mental disorders through occupational stress. BDNF gene (rs6265) and TPH2 gene (rs4570625) can indirectly affect mental disorders through MSDs. There may be an interaction between MSDs and educational level.

CONCLUSIONS

Besides demographic characteristics, occupational stress and musculoskeletal disorders are also factors affecting the mental health of coal miners. It was found that BDNF rs10835210, TPH2 rs4570625 and TPH2 rs4131347 interact with each other, increasing the risk of mental disorders among coal miners.

Reward sensitivity, affective neuroscience personality, symptoms of attention-deficit/hyperactivity disorder, and TPH2-703G/T (rs4570625) genotype

OBJECTIVE

Reward sensitivity is an increasingly used construct in psychiatry, yet its possible inner structure and relationship with other affective variables are not well known.

METHODS

A reward sensitivity measurement scale was constructed on the basis of large item pool collected from birth cohort representative samples (the Estonian Children Personality Behaviour and Health Study; original n = 1238). Affective Neuroscience Personality Scale (ANPS) and the Adult Attention deficit hyperactivity disorder (ADHD) Self-Report Scale (ASRS) were administered in young adulthood. A variant (rs4570625) of the gene encoding tryptophan hydroxylase 2 (TPH2) that is responsible for the synthesis of central serotonin was genotyped.

RESULTS

Reward sensitivity consisted of two orthogonal components, operationally defined as Openness to Rewards and Insatiability by Reward, that respectively characterise the striving towards multiple rewards and the strong pursuit and fixation to a particular reward. While SEEKING and PLAY (and to lower extent CARE) of the ANPS co-varied with Openness to Rewards, FEAR, SADNESS, and ANGER were related to Insatiability by Reward. The total score of ASRS was moderately correlated with Insatiability by Reward, while the association with Openness to Rewards was negligible. However, ASRS Inattention had some negative relationship with the Social Experience facet of Openness to Rewards. The T/T homozygotes for the TPH2 promoter polymorphism had lower Insatiability by Reward but not Openness to Rewards.

CONCLUSIONS

Behaviours sensitive to rewards are separable to the components of variability and fixation, and these components are differentially related to affective aspects of personality, attention, and hyperactivity as well as to TPH2 genotype.

The role of TPH2 variant rs4570625 in shaping infant attention to social signals

TPH2, the rate-limiting enzyme in the synthesis of serotonin, has been connected to several psychiatric outcomes. Its allelic variant, rs4570625, has been found to relate to individual differences in cognitive and emotion regulation during infancy with T-carriers of rs4570625 showing a relatively heightened attention bias for fearful faces. A significant gene-environment interaction was also reported with the T-carriers of mothers with depressive symptoms showing the highest fear bias. We investigated these associations in a sample of 8-month old infants (N = 330), whose mothers were prescreened for low/high levels of prenatal depressive and/or anxiety symptoms. Attention disengagement from emotional faces (neutral, happy, fearful, and phase-scrambled control faces) to distractors was assessed with eye tracking and an overlap paradigm. Maternal depressive symptoms were assessed at several time points during pregnancy and postpartum. The mean levels of symptoms at six months postpartum and the trajectories of symptoms from early pregnancy until six months postpartum were used in the analyses (N = 274). No main effect of the rs4570625 genotype on attention disengagement was found. The difference in fear bias between the genotypes was significant but in an opposite direction compared to a previous study. The results regarding the interaction of the genotype and maternal depression were not in accordance with the previous studies. These results show inconsistencies in the effects of the rs4570625 genotype on attention biases in separate samples of infants from the same population with only slight differences in age.

The Role of Irisin in Alzheimer's Disease

Alzheimer’s disease (AD) is characterized by progressive memory dysfunction, oxidative stress, and presence of senile plaques formed by amyloid beta (Aβ) accumulation in the brain. AD is one of the most important causes of morbidity and mortality worldwide. AD has a variety of risk factors, including environmental factors, metabolic dysfunction, and genetic background. Recent research has highlighted the relationship between AD and systemic metabolic changes such as glucose and lipid imbalance and insulin resistance. Irisin, a myokine closely linked to exercise, has been associated with glucose metabolism, insulin sensitivity, and fat browning. Recent studies have suggested that irisin is involved in the process in central nervous system (CNS) such as neurogenesis and has reported the effects of irisin on AD as one of the neurodegenerative disease. Here, we review the roles of irisin with respect to AD and suggest that irisin highlight therapeutic important roles in AD. Thus, we propose that irisin could be a potential future target for ameliorating AD pathology and preventing AD onset.

Association of Fatigue With TPH2 Genetic Polymorphisms in Women With Irritable Bowel Syndrome

Fatigue is the most common extraintestinal symptom in women with irritable bowel syndrome (IBS). Genetic polymorphisms of monoamines are associated with fatigue in many chronic diseases. In this pilot exploratory study, the primary aim was to determine whether genetic polymorphisms of tryptophan hydroxylase ( TPH1/TPH2), serotonin reuptake transporter ( SERT), or catechol-O-methyltransferase ( COMT) are associated with fatigue in women with IBS. Additionally, analysis explored whether these genetic associations with fatigue would be present when controlling for abdominal pain, psychological distress, feeling stressed, and sleepiness during the day. Secondary analysis of two randomized controlled trial baseline data sets in Caucasian women with IBS ( N = 185) was conducted. Participants kept a daily diary with one dimension (i.e., severity) for each of the 26 symptoms, including fatigue, for 28 days prior to randomization. DNA samples were tested for single-nucleotide polymorphisms (SNPs) of TPH1 (four SNPs) /TPH2 (one SNP), SERT (one SNP), and COMT (one SNP). Analysis of covariance was used to examine associations of percentage of diary days with moderate to very severe symptoms with genetic polymorphisms. Only one SNP, TPH2 rs4570625, was significantly associated with fatigue ( p = .005). T-allele (low functional) carriers of TPH2 (i.e., G/T or T/T genotypes) reported a greater percentage of days with moderate to very severe fatigue than G/G homozygotes ( p = .001). Reduced synthesis of tryptophan in the central nervous system may contribute to reports of fatigue in women with IBS. Understanding genetic risk factors for fatigue may elucidate preemptive strategies to reduce fatigue in individuals with IBS.

The Alteration of Irisin-Brain-Derived Neurotrophic Factor Axis Parallels Severity of Distress Disorder in Bronchial Asthma Patients

Distress disorder (a collective term for generalized anxiety disorder and major depressive disorder) is a well-known co-morbidity of bronchial asthma. The irisin-brain-derived neurotrophic factor (BDNF) axis is a pathway that influences several neurobehavioral mechanisms involved in the pathogenesis of distress disorder. Thus, the aim of the present study was to quantify the serum irisin and BDNF concentrations in order to investigate the possible link between the irisin/BDNF axis and distress disorder in an asthma patient cohort. Data of 167 therapy-controlled asthma patients were analyzed. Demographic, anthropometric, and anamnestic data were collected, routine laboratory parameters supplemented with serum irisin and BDNF levels were determined, pulmonary function test was performed using whole-body plethysmography, and quality of life was quantified by means of the St. George's Respiratory Questionnaire (SGRQ). Correlation analysis as well as simple and multiple linear regression were used to assess the relationship between the irisin level and the Impacts score of SGRQ, which latter is indicative of the presence and severity of distress disorder. We have found a significant, positive linear relationship between the Impacts score and the reciprocal of irisin level. This association was stronger in patients whose BDNF level was higher, and it was weaker (and statistically non-significant) in patients whose BDNF level was lower. Our results indicate that higher serum irisin level together with higher serum BDNF level are associated with milder (or no) distress disorder. This finding suggests that alteration of the irisin/BDNF axis influences the presence and severity of distress disorder in asthma patients.