Unravelling the interaction between the DRD2 and DRD4 genes, personality traits and concussion risk

The role of the genetic influence of DRD4 in Chinese adults in the context of the choice of tourist attractions

The aim of this work was to analyse the effect of tandem repetitions in exon III of the DRD4 gene on the features of human decision-making in a model of choosing tourist attractions by adult residents of China. The study included 380 subjects: 162 (42.6%) men and 218 (57.4%) women. The mean age of the subjects was 31.7 ± 3.32 years. As a result of the survey of subjects, 5 groups of motivations for choosing tourist attractions were identified, and the frequency of their use, including the identified combinations, was determined. Using the genotyping method, the frequency of DRD4 subtypes among the subjects was determined, and their relationship with the indicated attraction selection groups was studied. It has been established that there is a significant dependence of the frequency of choosing the attractors 'relaxation', 'desire for novelty' and 'self-realization' and their combinations on the frequency of occurrence of the DRD4 2R, 4R and 5R+ subtypes in the study groups. A conclusion was made about the possible mechanism of the influence of manifestations of DRD4 subtypes on the choice of tourist attractors by implementing the neurophysiological influence of the genome on reducing the sensitivity of brain receptors to dopamine, which stimulates behaviours that compensate for the need for additional emotional influences. This work complements the existing knowledge about the impact of human innate properties on the characteristics of his behaviour and possible patterns of influence of human genotype variability on decision-making and suggests further possible directions of research in this area.

A preliminary study on the association of single nucleotide polymorphisms and methylation of dopamine system-related genes with psychotic symptoms in patients with methamphetamine use disorder

Methamphetamine use disorder (MAUD) can substantially jeopardize public security due to its high-risk social psychology and behaviour. Given that the dopamine reward system is intimately correlated with MAUD, we investigated the association of single nucleotide polymorphisms (SNPs), as well as methylation status of dopamine receptor type 4 (DRD4), catechol-O-methyltransferase (COMT) genes, and paranoid and motor-impulsive symptoms in MAUD patients. A total of 189 MAUD patients participated in our study. Peripheral blood samples were used to detect 3 SNPs and 35 CpG units of methylation in the DRD4 gene promoter region and 5 SNPs and 39 CpG units in the COMT gene. MAUD patients with the DRD4 rs1800955 C allele have a lower percentage of paranoid symptoms than those with the rs1800955 TT allele. Individuals with paranoid symptoms exhibited a reduced methylation degree at a particular DRD4 CpG2.3 unit. The interaction of the DRD4 rs1800955 C allele and the reduced DRD4CpG2.3 methylation degree were associated with a lower occurrence of paranoid symptoms. Meanwhile, those with the COMT rs4818 CC allele had lower motor-impulsivity scores in MAUD patients but greater COMT methylation levels in the promoter region and methylation degree at the COMT CpG 51.52 unit. Therefore, based only on the COMT rs4818 CC polymorphism, there was a negative correlation between COMT methylation and motor-impulsive scores. Our preliminary results provide a clue that the combination of SNP genotype and methylation status of the DRD4 and COMT genes serve as biological indicators for the prevalence of relatively high-risk psychotic symptoms in MAUD patients.

Analysis of neurotransmitters validates the importance of the dopaminergic system in autism spectrum disorder

BACKGROUND

The reasons behind the cardinal symptoms of communication deficits and repetitive, stereotyped behaviors that characterize autism spectrum disorder (ASD) remain unknown. The dopamine (DA) system, which regulates motor activity, goal-directed behaviors, and reward function, is believed to play a crucial role in ASD, although the exact mechanism is still unclear. Investigations have shown an association of the dopamine receptor D4 (DRD4) with various neurobehavioral disorders.

METHODS

We analyzed the association between ASD and four DRD4 genetic polymorphisms, 5' flanking 120-bp duplication (rs4646984), rs1800955 in the promoter, exon 1 12 bp duplication (rs4646983), and exon 3 48 bp repeats. We also examined plasma DA and its metabolite levels, DRD4 mRNA expression, and correlations of the studied polymorphisms with these parameters by case-control comparative analyses. The expression of DA transporter (DAT), which is important in regulating the circulating DA level, was also evaluated.

RESULTS

A significantly higher occurrence of rs1800955 "T/TT" was observed in the probands. ASD traits were affected by rs1800955 "T" and the higher repeat alleles of the exon 3 48 bp repeats, rs4646983 and rs4646984. ASD probands exhibited lower DA and norepinephrine levels together with higher homovanillic acid levels than the control subjects. DAT and DRD4 mRNA expression were down-regulated in the probands, especially in the presence of DAT rs3836790 "6R" and rs27072 "CC" and DRD4 rs4646984 higher repeat allele and rs1800955 "T".

CONCLUSION

This pioneering investigation revealed a positive correlation between genetic variants, hypodopaminergic state, and impairment in socio-emotional and communication reciprocity in Indian subjects with ASD, warranting further in-depth analysis.

When should an athlete retire or discontinue participating in contact or collision sports following sport-related concussion? A systematic review

OBJECTIVE

To systematically review the scientific literature regarding factors to consider when providing advice or guidance to athletes about retirement from contact or collision sport following sport-related concussion (SRC), and to define contraindications to children/adolescent athletes entering or continuing with contact or collision sports after SRC.

DATA SOURCES

Medline, Embase, SPORTSDiscus, APA PsycINFO, CINAHL and Cochrane Central Register of Controlled Trials were searched systematically.

STUDY ELIGIBILITY CRITERIA

Studies were included if they were (1) original research, (2) reported on SRC as the primary source of injury, (3) evaluated the history, clinical assessment and/or investigation of findings that may preclude participation in sport and (4) evaluated mood disturbance and/or neurocognitive deficits, evidence of structural brain injury or risk factors for increased risk of subsequent SRC or prolonged recovery.

RESULTS

Of 4355 articles identified, 93 met the inclusion criteria. None of the included articles directly examined retirement and/or discontinuation from contact or collision sport. Included studies examined factors associated with increased risk of recurrent SRC or prolonged recovery following SRC. In general, these were low-quality cohort studies with heterogeneous results and moderate risk of bias. Higher number and/or severity of symptoms at presentation, sleep disturbance and symptom reproduction with Vestibular Ocular Motor Screen testing were associated with prolonged recovery and history of previous concussion was associated with a risk of further SRC.

CONCLUSION

No evidence was identified to support the inclusion of any patient-specific, injury-specific or other factors (eg, imaging findings) as absolute indications for retirement or discontinued participation in contact or collision sport following SRC.

PROSPERO REGISTRATION NUMBER

CRD42022155121.

DRD4 polymorphism associated with greater positive affect in response to negative and neutral social stimuli

Despite the robustness of DRD4 polymorphism associations with brain-based behavioral characteristics in candidate gene research, investigations have minimally explored associations between these polymorphisms and emotional responses. In particular, the prevalent single nucleotide polymorphism (SNP) -521C/T (rs1800955) in the promoter region of DRD4 remains unexplored relative to emotions. Here, two independent samples were evaluated using different emotion elicitation tasks involving social stimuli: Study 1 (N = 120) evoked positive and negative emotional responses to validated film clips; Study 2 (N = 122) utilized Cyberball to simulate social rejection and acceptance. Across studies, C/C individuals self-reported higher mean positive affect scores using Likert scales versus T carrier individuals, selectively when presented with neutral or negative (but not positive) social stimuli. The consistent findings across these two studies supports a functional consequence of this DRD4 SNP on emotion processing during changing social contexts. Continued investigation will help clarify if a C/C genotype enhances positive emotions under negative circumstances, or if the presence of the T allele reduces positive emotions, and how rs1800955 behavioral associations might generalize across different demographics. Future studies could also reveal if this SNP interacts with other changing environmental conditions to affect emotional responses, such as social limitations during the COVID-19 pandemic.

Forensic Value of Genetic Variants Associated with Anti-Social Behavior

Insanity defense is sometimes invoked in criminal cases, and its demonstration is usually based on a multifactorial contribution of behavioural, clinical, and neurological elements. Neuroradiological evidence of structural alterations in cerebral areas that involve decision-making and moral reasoning is often accepted as a useful tool in these evaluations. On the other hand, the genetic predisposition to anti-social behavior is still controversial. In this paper, we describe two cases of violent crimes committed by young carriers of genetic variants associated with personality disorder; both the defendants claimed to be insane at the time of the crime. We discuss these cases and review the scientific literature regarding the relationship between legal incapacity/predisposition to criminal behavior and genetic mutations. In conclusion, despite some genetic variants being able to influence several cognitive processes (like moral judgement and impulse control), there is currently no evidence that carriers of these mutations are, per se, incapable of intentionally committing crimes.

Association between Polymorphism rs1799732 of DRD2 Dopamine Receptor Gene and Personality Traits among MMA Athletes

Four factors—namely, harm avoidance, novelty seeking, reward addiction and persistence—represent the nature of temperament that is not genetically determined in itself. It was shown in earlier studies that a strong propensity to look for novelty or a tendency to engage in risky behavior is correlated with genetic variants in the area of the genes encoding dopamine receptors. Therefore, the aim of this study is to determine whether there is a relationship between personality traits and genetic variants in the area of the DRD2 dopamine receptor gene in MMA athletes. The participants consisted of 85 mixed martial arts (MMA) athletes and 284 healthy, non-MMA male participants. Their personality traits were measured using the Revised Temperament and Character Inventory. Blood was collected for genetic assays and all samples were genotyped using the real-time PCR method. We observed a statistically significant effect of a complex factor of the DRD2 rs1799732 genotype on MMA participants’ control and reward dependence. Engaging in high-risk sport may be associated with several personality characteristics. The DRD2 rs1799732 polymorphism may be associated with reduced harm avoidance in martial arts athletes, thereby modulating athletes’ predisposition to participate in high-risk sport.

Identification of Three Loci Associated with Achilles Tendon Injury Risk from a Genome-wide Association Study

PURPOSE

This study aimed to screen the entire genome for genetic markers associated with risk for Achilles tendon injury.

METHODS

A genome-wide association analysis was performed using data from the Kaiser Permanente Research Board and the UK Biobank. Achilles tendon injury cases were identified based on electronic health records from the Kaiser Permanente Research Board databank and the UK Biobank from individuals of European ancestry. Genome-wide association analyses from both cohorts were tested for Achilles tendon injury using a logistic regression model adjusting for sex, height, weight, and race/ethnicity using allele counts for single nucleotide polymorphisms (SNP). Previously identified genes within the literature were also tested for association with Achilles tendon injury.

RESULTS

There were a total of 12,354 cases of Achilles tendon injury and 483,080 controls within the two combined cohorts, with 67 SNP in three chromosomal loci demonstrating a genome-wide significant association with Achilles tendon injury. The first locus contains a single SNP (rs183364169) near the CDCP1 and TMEM158 genes on chromosome 3. The second locus contains 65 SNP in three independently segregating sets near the MPP7 gene on chromosome 10. The last locus contains a single SNP (rs4454832) near the SOX21 and GPR180 genes on chromosome 13. The current data were used to test 14 candidate genes previously reported to show an association with Achilles tendon injury, but none showed a significant association (all P > 0.05).

CONCLUSION

Three loci were identified as potential risk factors for Achilles tendon injury and deserve further validation and investigation of molecular mechanisms.

A Genome-wide Association Study for Concussion Risk

PURPOSE

This study aimed to screen the entire genome for genetic markers associated with risk for concussion.

METHODS

A genome-wide association analyses was performed using data from the Kaiser Permanente Research Bank and the UK Biobank. Concussion cases were identified based on electronic health records from the Kaiser Permanente Research Bank and the UK Biobank from individuals of European ancestry. Genome-wide association analyses from both cohorts were tested for concussion using a logistic regression model adjusting for sex, height, weight, and race/ethnicity using allele counts for single nucleotide polymorphisms. Previously identified genes within the literature were also tested for association with concussion.

RESULTS

There were a total of 4064 cases of concussion and 291,472 controls within the databases, with two single nucleotide polymorphisms demonstrating a genome-wide significant association with concussion. The first polymorphism, rs144663795 (P = 9.7 × 10-11; OR = 2.91 per allele copy), is located within the intron of SPATA5. Strong, deleterious mutations in SPATA5 cause intellectual disability, hearing loss, and vision loss. The second polymorphism, rs117985931 (P = 3.97 × 10-9; OR = 3.59 per allele copy), is located within PLXNA4. PLXNA4 plays a key role is axon outgrowth during neural development, and DNA variants in PLXNA4 are associated with risk for Alzheimer's disease. Previous investigations have identified five candidate genes that may be associated with concussion, but none showed a significant association in the current model (P < 0.05).

CONCLUSION

Two genetic markers were identified as potential risk factors for concussion and deserve further validation and investigation of molecular mechanisms.

Sensation-Seeking and Impulsivity in Athletes with Sport-Related Concussion

PURPOSE OF REVIEW

Sport-related concussion (SRC) is a significant public health problem. Understanding the behavioral and personal factors that influence risk and incidence of SRC is critically important for appropriate care and management. Sensation-seeking and impulsivity have been posited to be two such factors that may be significantly associated with SRC. We performed a focused review of recent evidence of the relationships between sensation-seeking and impulsivity in athletes with SRC.

RECENT FINDINGS

While the research is relatively limited, extant findings demonstrate a significant relationship between sensation-seeking and contact sport participation and risk of prior and future SRC. Impulsivity appears to be common among athletes competing in high contact sports and may contribute to neural and functional brain changes following SRC; however, causal relationships between impulsivity, contact sport participation, and SRC have not been demonstrated. Both sensation-seeking and impulsivity are significantly associated with SRC in collegiate athletes. Interventions designed to ameliorate high levels of these constructs may prove to be beneficial avenues to reducing SRC risk and improving patient care and outcomes.

The Immune System's Role in the Consequences of Mild Traumatic Brain Injury (Concussion)

Mild traumatic brain injury (mild TBI), often referred to as concussion, is the most common form of TBI and affects millions of people each year. A history of mild TBI increases the risk of developing emotional and neurocognitive disorders later in life that can impact on day to day living. These include anxiety and depression, as well as neurodegenerative conditions such as chronic traumatic encephalopathy (CTE) and Alzheimer's disease (AD). Actions of brain resident or peripherally recruited immune cells are proposed to be key regulators across these diseases and mood disorders. Here, we will assess the impact of mild TBI on brain and patient health, and evaluate the recent evidence for immune cell involvement in its pathogenesis.

Genetic Factors That Could Affect Concussion Risk in Elite Rugby

Elite rugby league and union have some of the highest reported rates of concussion (mild traumatic brain injury) in professional sport due in part to their full-contact high-velocity collision-based nature. Currently, concussions are the most commonly reported match injury during the tackle for both the ball carrier and the tackler (8-28 concussions per 1000 player match hours) and reports exist of reduced cognitive function and long-term health consequences that can end a playing career and produce continued ill health. Concussion is a complex phenotype, influenced by environmental factors and an individual's genetic predisposition. This article reviews concussion incidence within elite rugby and addresses the biomechanics and pathophysiology of concussion and how genetic predisposition may influence incidence, severity and outcome. Associations have been reported between a variety of genetic variants and traumatic brain injury. However, little effort has been devoted to the study of genetic associations with concussion within elite rugby players. Due to a growing understanding of the molecular characteristics underpinning the pathophysiology of concussion, investigating genetic variation within elite rugby is a viable and worthy proposition. Therefore, we propose from this review that several genetic variants within or near candidate genes of interest, namely APOE, MAPT, IL6R, COMT, SLC6A4, 5-HTTLPR, DRD2, DRD4, ANKK1, BDNF and GRIN2A, warrant further study within elite rugby and other sports involving high-velocity collisions.

Associations between the dopamine D4 receptor gene polymorphisms and personality traits in elite athletes

Personality traits and temperament may affect sports performance. Previous studies suggest that dopamine may play an important role in behavior regulation and physical exercise performance. The aim of this study is to determine associations between dopamine D4 receptor gene (DRD4 Ex3) polymorphisms and personality traits (such as neuroticism, extraversion, openness, agreeability and conscientiousness) in elite combat athletes. A total of 302 physically active, unrelated, self-reported Caucasian participants were recruited for this study. The participants consisted of 200 elite male combat athletes and 102 healthy male participants (control group). For personality trait measurements, the NEO Five-Factor Personality Inventory (NEO-FFI) and the State-Trait Anxiety Inventory questionnaires were used. For the genetic assays, blood was collected and all samples were genotyped using the real-time PCR method. A 2 x 3 factorial ANOVA revealed statistically significant differences on the Openness NEO Five Factor Inventory scale for both examined factors, i.e. sport status and genetics DTD4 Ex3. Combat athletes achieved higher scores on the Conscientiousness NEO-FFI scale when compared to controls (7.18 vs 5.98). On the other hand, combat athletes scored lower on the Openness scale in comparison with control group (4.42 vs. 4.63). Subjects with the DRD4 Ex3 s/s genotype had lower results on the openness scale in comparison with participants with the DRD4 Ex3 s/1 genotype (4.01 vs. 4.57) and higher DRD4 Ex3 1/1 genotype (4,01 vs. 3,50). In conclusion, we found an association between the dopamine D4 receptor gene in variable number tandem repeat (VNTR) polymorphisms and athletic status for two NEO-FFI factors: Openness and Conscientiousness. The DRD4 exon 3 polymorphism may be associated with the selected personality traits in combat athletes, thereby modulating athletes’ predisposition to participate in high risk sports.