Assessing the molecular genetics of attention networks

Mesocorticolimbic dopamine functioning in primary psychopathy: A source of within-group heterogeneity

Despite similar emotional deficiencies, primary psychopathic individuals can be situated on a continuum that spans from controlled to disinhibited. The constructs on which primary psychopaths are found to diverge, such as self-control, cognitive flexibility, and executive functioning, are crucially regulated by dopamine (DA). As such, the goal of this review is to examine which specific alterations in the meso-cortico-limbic DA system and corresponding genes (e.g., TH, DAT, COMT, DRD2, DRD4) might bias development towards a more controlled or disinhibited expression of primary psychopathy. Based on empirical data, it is argued that primary psychopathy is generally related to a higher tonic and population activity of striatal DA neurons and lower levels of D2-type DA receptors in meso-cortico-limbic projections, which may boost motivational drive towards incentive-laden goals, dampen punishment sensitivity, and increase future reward-expectancy. However, increasingly higher levels of DA activity in the striatum (moderate versus pathological elevations), lower levels of DA functionality in the prefrontal cortex, and higher D1-to-D2-type receptor ratios in meso-cortico-limbic projections may lead to increasingly disinhibited and impetuous phenotypes of primary psychopathy. Finally, in order to provide a more coherent view on etiological mechanisms, we discuss interactions between DA and serotonin that are relevant for primary psychopathy.

The attentive brain: insights from developmental cognitive neuroscience

Visual attention functions as a filter to select environmental information for learning and memory, making it the first step in the eventual cascade of thought and action systems. Here, we review studies of typical and atypical visual attention development and explain how they offer insights into the mechanisms of adult visual attention. We detail interactions between visual processing and visual attention, as well as the contribution of visual attention to memory. Finally, we discuss genetic mechanisms underlying attention disorders and how attention may be modified by training.

Effect of Experimental Thyrotoxicosis on Brain Gray Matter: A Voxel-Based Morphometry Study

BACKGROUND

Hyper-as well hypothyroidism have an effect on behavior and brain function. Moreover, during development thyroid hormones influence brain structure.

OBJECTIVES

This study aimed to demonstrate an effect of experimentally induced hyperthyroidism on brain gray matter in healthy adult humans.

METHODS

High-resolution 3D T1-weighted images were acquired in 29 healthy young subjects prior to as well as after receiving 250 µg of T4 per day for 8 weeks. Voxel-based morphometry analysis was performed using Statistical Parametric Mapping 8 (SPM8).

RESULTS

Laboratory testing confirmed the induction of hyperthyroidism. In the hyperthyroid condition, gray matter volumes were increased in the right posterior cerebellum (lobule VI) and decreased in the bilateral visual cortex and anterior cerebellum (lobules I-IV) compared to the euthyroid condition.

CONCLUSIONS

Our study provides evidence that short periods of hyperthyroidism induce distinct alterations in brain structures of cerebellar regions that have been associated with sensorimotor functions as well as working memory in the literature.

DRD2 and DRD4 genes related to cognitive deficits in HIV-infected adults who abuse alcohol

Background

HIV-infected individuals continue to experience neurocognitive deterioration despite virologically successful treatments. The causes of neurocognitive impairment are still unclear. However, several factors have been suggested including the role of genetics. There is evidence suggesting that neurocognitive impairment is heritable and individual differences in cognition are strongly driven by genetic variations. The contribution of genetic variants affecting the metabolism and activity of dopamine may influence these individual differences.

Methods

The present study explored the relationship between two candidate genes (DRD4 and DRD2) and neurocognitive performance in HIV-infected adults. A total of 267 HIV-infected adults were genotyped for polymorphisms, DRD4 48 bp-variable number tandem repeat (VNTR), DRD2 rs6277 and ANKK1 rs1800497. The Short Category (SCT), Color Trail (CTT) and Rey-Osterrieth Complex Figure Tests (ROCT) were used to measure executive function and memory.

Results

Results showed significant associations with the SNP rs6277 and impaired executive function (odds ratio = 3.3, 95 % CI 1.2–2.6; p = 0.004) and cognitive flexibility (odds ratio = 1.6, 95 % CI 2.0–5.7; p = 0.001). The results were further stratified by race and sex and significant results were seen in males (odds ratio = 3.5, 95 % CI 1.5–5.5; p = 0.008) and in African Americans (odds ratio = 3.1, 95 % CI 2.3–3.5; p = 0.01). Also, DRD4 VNTR 7-allele was significantly associated with executive dysfunction.

Conclusion

The study shows that genetically determined differences in the SNP rs6277 DRD2 gene and DRD4 48 bp VNTR may be risk factors for deficits in executive function and cognitive flexibility.

Experimentally induced thyrotoxicosis leads to increased connectivity in temporal lobe structures: a resting state fMRI study

Adult onset hyperthyroidism may impact on different cognitive domains, including attention and concentration, memory, perceptual function, language and executive function. Previous PET studies implicated changed functionality of limbic regions, the temporal and frontal lobes in hyperthyroidism, whereas it is unknown whether cognitive effects of hyperthyroidism may be due to changed brain connectivity. This study aimed to investigate the effect of experimentally induced short-term hyperthyroidism thyrotoxicosis on resting-state functional connectivity using functional magnetic resonance imaging. Twenty-nine healthy male right-handed subjects were examined twice, once prior and once after 8 weeks of oral administration of 250 μg levothyroxine per day. Resting-state fMRI was subjected to graph-theory based analysis methods to investigate whole-brain intrinsic functional connectivity. Despite a lack of subjective changes noticed by the subjects significant thyrotoxicosis was confirmed in all subjects. This induced a significant increase in resting-state functional connectivity specifically in the rostral temporal lobes (0.05 FDR corrected at the cluster level), which is caused by an increased connectivity to the cognitive control network. The increased connectivity between temporal poles and the cognitive control network shown here under experimental conditions supports an important function of thyroid hormones in the regulation of paralimbic structures.

DRD4 Genotype and the Developmental Link of Peer Social Preference with Conduct Problems and Prosocial Behavior Across Ages 9-12 Years

The peer environment is among the most important factors for children’s behavioral development. However, not all children are equally influenced by their peers, which is potentially due to their genetic make-up. The dopamine receptor D4 gene (DRD4) is a potential candidate gene that may influence children’s susceptibility to the peer environment. In the present study, we explored whether variations in the DRD4 gene moderated the association between children’s social standing in the peer group (i.e., social preference among classmates) with subsequent conduct problems and prosocial behavior among 405 (51 % females) elementary school children followed annually throughout early adolescence (ages 9–12 years). The behavioral development of children with and without the DRD4 7-repeat allele was compared. The results indicated that children who had higher positive social preference scores (i.e., who were more liked relative to disliked by their peers) showed less conduct problem development in subsequent years relative to children who had lower positive social preference scores. In contrast, children who had more negative preference scores (i.e., who were more disliked relative to liked among peers) showed more conduct problem development in subsequent years, relative to children who had less negative preference scores. However, these effects only occurred when children had a 7-repeat allele. For children who did not have a 7-repeat allele, the level of social preference was not associated with subsequent conduct problems. No evidence for gene–environment interaction effects for prosocial behavior was found. The implications for our understanding of conduct problem development and its prevention are discussed.

Modulation of prefrontal functioning in attention systems by NPSR1 gene variation

Evidence has accumulated for a dysfunction of arousal and executive attention in anxiety. The neuropeptide S (NPS) system has been shown to play a pivotal role in the mediation of arousal and to be associated with anxiety/panic disorder. The present study aims at investigating the impact of functional neuropeptide S receptor (NPSR1) gene variation on neural attention patterns applying an imaging genetics approach. In an event-related functional magnetic resonance imaging (fMRI) setting, 47 healthy subjects (f=23) evenly pre-stratified for NPSR1 rs324981 A/T genotype were investigated for brain activation patterns while performing the Attention Network Task (ANT), simultaneously probing alerting and executive control functions. Anxiety sensitivity was ascertained by the Anxiety Sensitivity Index (ASI). In the alerting condition, NPSR1 TT homozygotes showed higher activations in the right prefrontal cortex and the locus coeruleus region as compared to A allele carriers. In the executive control condition, TT homozygotes displayed increased activations in fronto-parietal regions. Genotype-driven activation differences in the prefrontal cortex correlated with anxiety sensitivity, in both the alerting and the executive control system. The present results for the first time suggest NPSR1 gene variation to be associated with alterations of prefrontal functioning in the attentional functions alerting and executive control partly modulated by anxiety sensitivity. These findings may aid in unraveling the neurobiological underpinnings of distorted arousal and attention in anxiety and thereby possibly in the biomarker-guided development of preventive/therapeutic strategies targeting attention processes in anxiety disorders.

Music training relates to the development of neural mechanisms of selective auditory attention

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Does music training shape the development of neural mechanisms of auditory attention?

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We compared cortical responses to attended speech in child and adult musicians and nonmusicians.

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Musician children and adults had less prefrontal auditory response variability during attention.

Selective attention decreases trial-to-trial variability in cortical auditory-evoked activity. This effect increases over the course of maturation, potentially reflecting the gradual development of selective attention and inhibitory control. Work in adults indicates that music training may alter the development of this neural response characteristic, especially over brain regions associated with executive control: in adult musicians, attention decreases variability in auditory-evoked responses recorded over prefrontal cortex to a greater extent than in nonmusicians. We aimed to determine whether this musician-associated effect emerges during childhood, when selective attention and inhibitory control are under development. We compared cortical auditory-evoked variability to attended and ignored speech streams in musicians and nonmusicians across three age groups: preschoolers, school-aged children and young adults. Results reveal that childhood music training is associated with reduced auditory-evoked response variability recorded over prefrontal cortex during selective auditory attention in school-aged child and adult musicians. Preschoolers, on the other hand, demonstrate no impact of selective attention on cortical response variability and no musician distinctions. This finding is consistent with the gradual emergence of attention during this period and may suggest no pre-existing differences in this attention-related cortical metric between children who undergo music training and those who do not.

Attentional processes in low-socioeconomic status bilingual children: are they modulated by the amount of bilingual experience?

Recent research indicates that bilingual children are more proficient in resolving cognitive conflict than monolinguals. However, the replicability of such findings has been questioned, with poor control of participants' socioeconomic status (SES) as a possible confounding factor. Two experiments are reported here, in which the main attentional functions and pragmatic ability of 54 bilingual and 56 monolingual low-SES children were assessed (Experiment 1: 6- to 12-year-olds; Experiment 2: 6- to 8-year-olds). A language-switching task was also employed, to measure bilingual proficiency. Overall, the monolingual and bilingual groups did not differ significantly in any of the tasks employed, although the ability to resolve conflict was related to children's level of bilingual experience.

Dopamine transporter SLC6A3 genotype affects cortico-striatal activity of set-shifts in Parkinson's disease

Parkinson's disease is a neurodegenerative condition that affects motor function along with a wide range of cognitive domains, including executive function. The hallmark of the pathology is its significant loss of nigrostriatal dopamine, which is necessary for the cortico-striatal interactions that underlie executive control. Striatal dopamine reuptake is mediated by the SLC6A3 gene (formerly named DAT1) and its polymorphisms, which have been largely overlooked in Parkinson's disease. Thirty patients (ages 53-68 years; 19 males, 11 females) at early stages of Parkinson's disease, were genotyped according to a 9-repeat (9R) or 10-repeat (10R) allele on the SLC6A3/DAT1 gene. They underwent neuropsychological assessment and functional magnetic resonance imaging while performing a set-shifting task (a computerized Wisconsin Card Sorting Task) that relies on fronto-striatal interactions. Patients homozygous on the 10R allele performed significantly better on working memory tasks than 9R-carrier patients. Most importantly, patients carrying a 9R allele exhibited less activation than their 10R homozygous counterparts in the prefrontal cortex, premotor cortex and caudate nucleus, when planning and executing a set-shift. This pattern was exacerbated for conditions that usually recruit the striatum compared to those that do not. This is the first study indicating that the SLC6A3/DAT1 genotype has a significant effect on fronto-striatal activation and performance in Parkinson's disease. This effect is stronger for conditions that engage the striatum. Longitudinal studies are warranted to assess this polymorphism's effect on the clinical evolution of patients with Parkinson's disease, especially with cognitive decline.

Symptoms of attention-deficit hyperactivity disorder, nonsyndromic orofacial cleft children, and dopamine polymorphisms: a pilot study

PURPOSE

Attention-deficit hyperactivity disorder (ADHD) is a common childhood neurobehavioral disorder characterized by inattention, poor impulse control, and motor restlessness. Risk factors include familial stressors, anxiety disorders, learning disabilities, abnormal brain development, heritability, and dopamine polymorphisms. Children with an orofacial clefting (OFC) history are at increased risk of familial stressors, anxiety disorders, learning disabilities, and abnormal brain development. Given this overlap, we present a conceptual model proposing that children with OFC may be more likely to exhibit ADHD symptoms than children without and explore this relationship using pilot data.

DESIGN

This cross-sectional pilot study included 29 children with OFC or a first-degree relative with OFC recruited through a cleft research registry.

METHODS

The Disruptive Behavior Disorder Scale was used to collect data on children's ADHD symptoms. Saliva or whole blood samples were collected from children and parents for DNA analyses. ADHD-associated dopamine polymorphisms within the DRD4, DRD2, and DAT1 genes were genotyped. We tested for associations between presence of OFC and dopamine polymorphisms. Mixed-effects models tested whether children with OFC and dopamine polymorphisms had more ADHD symptoms.

RESULTS

The DRD4 4-repeat allele was associated with increased inattentive ADHD symptoms (p = .03). Having the DRD2 Taq1A1 allele and OFC predicted fewer (p = .02) inattentive ADHD symptoms. Children with OFC were significantly less likely to have the DAT1 10-repeat allele (p = .04).

CONCLUSIONS

Results indicate that further investigation among a larger sample of children with OFC is warranted, particularly for relationships with inattentive ADHD.

Examination of daytime sleepiness and cognitive performance testing in patients with primary insomnia

Objective

While individuals with insomnia consistently complain of cognitive impairment, previous studies on the effect of insomnia on objective measures of cognitive function have obtained ambiguous results. The relationship between daytime sleepiness and cognitive manifestations in insomnia patients is not clear.

Methods

Thirty-six primary insomnia patients (PIPs) and 26 good sleep controls (GSCs) with age and gender matched manner were included in the study. Participants underwent an overnight polysomnography followed by a multiple sleep latency test (MSLT) and an examination of the attention network test (ANT). ANT reflected three attentional networks including alerting, orienting and executive control. According to whether accompanied with excessive daytime sleepiness (EDS), the insomnia group were subdivided into PIPs with EDS (n = 12, score on MSLT<10 min) and PIPs without EDS (n = 24, score on MSLT≥10 min).

Results

PIPs only performed worse on executive control function than GSCs in ANT. PIPs with EDS had longer overall reaction time (RT) related to PIPs without EDS. Further analyses with Pearson correlation analysis showed a significant negative correlation between the overall RT and MSLT latency in insomniacs (r = −0.444, p<0.01), whereas no such correlation was found in controls.

Conclusions

Results suggest that PIPs do show executive control function deficits compared with GSCs. Daytime sleepiness in terms of MSLT latency was associated with poor cognitive manifestations in patients with insomnia.

Proposed mechanisms for cancer- and treatment-related cognitive changes

OBJECTIVES

To review the proposed mechanisms of cognitive changes associated with non-central nervous system cancers and cancer treatment.

DATA SOURCES

Review and synthesis of databased publications and review articles.

CONCLUSION

Proposed mechanisms include cytokine upregulation, hormonal changes, neurotransmitter dysregulation, attentional fatigue, genetic predisposition, and comorbid symptoms.

IMPLICATIONS FOR NURSING PRACTICE

Oncology nurses need to understand the multiple mechanisms that may contribute to the development of cancer- and treatment-related cognitive changes so that they can identify patients at high risk and help patients understand why these changes occur.

Testing attention: comparing the ANT with TVA-based assessment

Posner's attention network model and Bundesen's theory of visual attention (TVA) are two influential accounts of attention. Each model has led to the development of a test method: the attention network test (ANT) and TVA-based assessment, respectively. Both tests have been widely used to investigate attentional function in normal and clinical populations. Here we report on the first direct comparison of the ANT to TVA-based assessment. A group of 68 young healthy participants were tested in three consecutive sessions that each contained standard versions of the two tests. The parameters derived from TVA-based assessment had better internal reliability and retest reliability than did those of the standard version of the ANT, where only the executive network score reached comparable levels. However, when corrected for differences in test length, the retest reliability of the orienting network score equaled the least reliable TVA parameters. Both tests were susceptible to practice effects, which improved performance for some parameters while leaving others constant. All pairwise correlations between the eight attention parameters measured by the two tests were small and nonsignificant, with one exception: A strong correlation (r = 0.72) was found between two parameters of TVA-based assessment, visual processing speed and the capacity of visual short-term memory. We conclude that TVA-based assessment and the ANT measure complementary aspects of attention, but the scores derived from TVA-based assessment are more reliable.

Drug abuse relapse rates linked to level of education: can we repair hypodopaminergic-induced cognitive decline with nutrient therapy?

It is well known that athletes and other individuals who have suffered painful injuries are at increased risk for all reward deficiency syndrome (RDS) behaviors, including substance use disorder (SUD). Comparing patient demographics and relapse rates in chemical dependence programs is pertinent because demographics may affect outcomes. Increased risk for relapse and lower academic achievement were found to have a significant association in recent outcome data from a holistic treatment center (HTC) located in North Miami Beach, FL. Relapse outcomes from the Drug Addiction Treatment Outcome Study (DATOS; n = 1738) and HTC (n = 224) were compared for a 12-month period. Post-discharge relapse was reported by 26% of HTC patients and 58% of patients in DATOS. When broken out by education level-less than high school, high school diploma, college degree, and graduate degree-HTC patient relapse was 50%, 36%, 33%, and 16%, respectively, and demonstrated an inverse linear association (F = 5.702; P = 0.017). Looking at DATOS patient relapse rates broken down by educational grades/years completed, patients who attended school between 7th grade and 4 years of college also demonstrated an inverse linear association (F = 5.563; P = 0.018). Additionally, the lowest performers, patients who reported their academic performance as "not so good," had the highest relapse (F = 4.226; P = 0.04). Albeit certain limitations, compared with DATOS patients, HTC patients produced significantly larger net differences in relapse rates (X 2 = 84.09; P = 0.0001), suggesting that other variables, such as the treatment model may also affect patient relapse. Our results implicate the use of vitamin and mineral supplements coupled with a well-researched natural dopamine agonist nutrient therapy; both have been shown to improve cognition and behavior, and thus academic achievement. That relapse is highest among addicts who have less education and who report lower grades is a factor that can be useful when considering treatment type and controlled for when comparing treatment outcomes.

Evidence of MAOA genotype involvement in spatial ability in males

Although the monoamine oxidase-A (MAOA) gene has been linked to spatial learning and memory in animal models, convincing evidence in humans is lacking. Performance on an ecologically-valid, virtual computer-based equivalent of the Morris Water Maze task was compared between 28 healthy males with the low MAOA transcriptional activity and 41 healthy age- and IQ-matched males with the high MAOA transcriptional activity. The results revealed consistently better performance (reduced heading error, shorter path length, and reduced failed trials) for the high MAOA activity individuals relative to the low activity individuals. By comparison, groups did not differ on pre-task variables or strategic measures such as first-move latency. The results provide novel evidence of MAOA gene involvement in human spatial navigation using a virtual analogue of the Morris Water Maze task.

Common and specific impairments in attention functioning in girls with chromosome 22q11.2 deletion, fragile X or Turner syndromes

Background

Chromosome 22q11.2 deletion syndrome (22q11.2DS), fragile X syndrome (FXS), and Turner syndrome (TS) are complex and variable developmental syndromes caused by different genetic abnormalities; yet, they share similar cognitive impairments in the domains of numbers, space, and time. The atypical development of foundational neural networks that underpin the attentional system is thought to result in further impairments in higher-order cognitive functions. The current study investigates whether children with similar higher-order cognitive impairments but different genetic disorders also show similar impairments in alerting, orienting, and executive control of attention.

Methods

Girls with 22q11.2DS, FXS, or TS and typically developing (TD) girls, aged 7 to 15 years, completed an attention network test, a flanker task with alerting and orienting cues. Exploration of reaction times and accuracy allowed us to test for potential commonalities in attentional functioning in alerting, orienting, and executive control. Linear regression models were used to test whether the predictors of group and chronological age were able to predict differences in attention indices.

Results

Girls with 22q11.2DS, FXS, or TS demonstrated unimpaired function of the alerting system and impaired function of the executive control system. Diagnosis-specific impairments were found such that girls with FXS made more errors and had a reduced orienting index, while girls with 22q11.2DS showed specific age-related deficits in the executive control system.

Conclusions

These results suggest that the control but not the implementation of attention is selectively impaired in girls with 22q11.2DS, TS or FXS. Additionally, the age effect on executive control in girls with 22q11.2DS implies a possible altered developmental trajectory.

A new method for computing attention network scores and relationships between attention networks

The attention network test (ANT) is a reliable tool to detect the efficiency of alerting, orienting, and executive control networks. However, studies using the ANT obtained inconsistent relationships between attention networks due to two reasons: on the one hand, the inter-network relationships of attention subsystems were far from clear; on the other hand, ANT scores in previous studies were disturbed by possible inter-network interactions. Here we proposed a new computing method by dissecting cue-target conditions to estimate ANT scores and relationships between attention networks as pure as possible. The method was tested in 36 participants. Comparing to the original method, the new method showed a larger alerting score and a smaller executive control score, and revealed interactions between alerting and executive control and between orienting and executive control. More interestingly, the new method revealed unidirectional influences from alerting to executive control and from executive control to orienting. These findings provided useful information for better understanding attention networks and their relationships in the ANT. Finally, the relationships of attention networks should be considered with more experimental paradigms and techniques.

Potential contribution of dopaminergic gene variants in ADHD core traits and co-morbidity: a study on eastern Indian probands

Association of dopaminergic genes, mainly receptors and transporters, with Attention Deficit Hyperactivity Disorder (ADHD) has been investigated throughout the world due to the importance of dopamine (DA) in various physiological functions including attention, cognition and motor activity, traits. However, till date, etiology of ADHD remains unknown. We explored association of functional variants in the DA receptor 2 (rs1799732 and rs6278), receptor 4 (exon 3 VNTR and rs914655), and transporter (rs28363170 and rs3836790) with hyperactivity, cognitive deficit, and co-morbid disorders in eastern Indian probands. Diagnostic and Statistical Manual for Mental Disorders-IV was followed for recruitment of nuclear families with ADHD probands (N = 160) and ethnically matched controls (N = 160). Cognitive deficit and hyperactive traits were measured using Conner's parents/teachers rating scale. Peripheral blood was collected after obtaining informed written consent and used for genomic DNA isolation. Genetic polymorphisms were analyzed by PCR-based methods followed by population- as well as family-based statistical analyses. Association between genotypes and cognitive/hyperactivity traits and co-morbidities was analyzed by the Multifactor dimensionality reduction (MDR) software. Case-control analysis showed statistically significant difference for rs6278 and rs28363170 (P = 0.004 and 1.332e-007 respectively) while family-based analysis exhibited preferential paternal transmission of rs28363170 '9R' allele (P = 0.04). MDR analyses revealed independent effects of rs1799732, rs6278, rs914655, and rs3836790 in ADHD. Significant independent effects of different sites on cognitive/hyperactivity traits and co-morbid disorders were also noticed. It can be summarized from the present investigation that these gene variants may influence cognitive/hyperactive traits, thereby affecting the disease etiology and associated co-morbid features.

Mitigating aggressiveness through education? The monoamine oxidase A genotype and mental health in general population

OBJECTIVE

Monoamine oxidase A (MAOA) gene promoter region includes a variable number of tandem repeat (VNTR) associated with antisocial behaviour in adverse environment. We have examined the effect of the MAOA-uVNTR on mental health and academic success by using a population representative sample and a longitudinal design.

METHODS

The data of the older cohort (n = 593, aged 15 years at the original sampling) of the longitudinal Estonian Children Personality, Behaviour and Health Study (ECPBHS) were used. Follow-ups were conducted at ages 18 and 25 years. Aggressiveness, inattention and hyperactivity were reported by class teachers or, at older age, self-reported. Stressful life events, psychological environment in the family and interactions between family members were self-reported. Data of general mental abilities and education were obtained at the age of 25, and lifetime psychiatric disorder assessment was carried out with the Mini-International Neuropsychiatric Interview (MINI) interview.

RESULTS

MAOA-uVNTR genotype had no independent effect on aggressiveness, hyperactive and inattentive symptoms, and neither was there a genotype interaction with adverse life events. Interestingly, the proportion of male subjects with higher education by the age of 25 was significantly larger among those with MAOA low-activity alleles (χ² = 7.13; p = 0.008). Logistic regression revealed that MAOA low-activity alleles, higher mental abilities, occurrence of anxiety disorders and absence of substance-use disorder were significant independent predictors for higher education in male subjects.

CONCLUSIONS

In a population representative sample of young subjects, the MAOA-uVNTR 'risk genotype' predicted better life outcomes as expressed in higher level of education.

Spontaneous neuronal activity predicts intersubject variations in executive control of attention

Executive control of attention regulates our thoughts, emotion and behavior. Individual differences in executive control are associated with task-related differences in brain activity. But it is unknown whether attentional differences depend on endogenous (resting state) brain activity and to what extent regional fluctuations and functional connectivity contribute to individual variations in executive control processing. Here, we explored the potential contribution of intrinsic brain activity to executive control by using resting-state functional magnetic resonance imaging (fMRI). Using the amplitude of low-frequency fluctuations (ALFF) as an index of spontaneous brain activity, we found that ALFF in the right precuneus (PCUN) and the medial part of left superior frontal gyrus (msFC) was significantly correlated with the efficiency of executive control processing. Crucially, the strengths of functional connectivity between the right PCUN/left msFC and distributed brain regions, including the left fusiform gyrus, right inferior frontal gyrus, left superior frontal gyrus and right precentral gyrus, were correlated with individual differences in executive performance. Together, the ALFF and functional connectivity accounted for 67% of the variability in behavioral performance. Moreover, the strength of functional connectivity between specific regions could predict more individual variability in executive control performance than regionally specific fluctuations. In conclusion, our findings suggest that spontaneous brain activity may reflect or underpin executive control of attention. It will provide new insights into the origins of inter-individual variability in human executive control processing.

Contributions of COMT Val¹⁵⁸ Met to cognitive stability and flexibility in infancy

Adaptive behavior requires focusing on relevant tasks while remaining sensitive to novel information. In adult studies of cognitive control, cognitive stability involves maintaining robust cognitive representations while cognitive flexibility involves updating of representations in response to novel information. Previous adult research has shown that the Met allele of the COMT Val(158) Met gene is associated with enhanced cognitive stability whereas the Val allele is associated with enhanced cognitive flexibility. Here we propose that the stability/flexibility framework can also be applied to infant research, with stability mapping onto early indices of behavioral regulation and flexibility mapping onto indices of behavioral reactivity. From this perspective, the present study examined whether COMT genotype was related to 7-month-old infants' reactivity to novel stimuli and behavioral regulation. Cognitive stability and flexibility were assessed using (1) a motor approach task, (2) a habituation task, and (3) a parental-report measure of temperament. Val carriers were faster to reach for novel toys during the motor approach task and received higher scores on the temperament measure of approach to novelty. Met carriers showed enhanced dishabituation to the novel stimulus during the habituation task and received higher scores on the temperament measures of sustained attention and behavioral regulation. Overall, these results are consistent with adult research suggesting that the Met and Val alleles are associated with increased cognitive stability and flexibility, respectively, and thus suggest that COMT genotype may similarly affect cognitive function in infancy.

Hypnotizability and Catechol-O-Methyltransferase (COMT) polymorphysms in Italians

Higher brain dopamine content depending on lower activity of Catechol-O-Methyltransferase (COMT) in subjects with high hypnotizability scores (highs) has been considered responsible for their attentional characteristics. However, the results of the previous genetic studies on association between hypnotizability and the COMT single nucleotide polymorphism (SNP) rs4680 (Val¹⁵⁸Met) were inconsistent. Here, we used a selective genotyping approach to re-evaluate the association between hypnotizability and COMT in the context of a two-SNP haplotype analysis, considering not only the Val¹⁵⁸Met polymorphism, but also the closely located rs4818 SNP. An Italian sample of 53 highs, 49 low hypnotizable subjects (lows), and 57 controls, were genotyped for a segment of 805 bp of the COMT gene, including Val¹⁵⁸Met and the closely located rs4818 SNP. Our selective genotyping approach had 97.1% power to detect the previously reported strongest association at the significance level of 5%. We found no evidence of association at the SNP, haplotype, and diplotype levels. Thus, our results challenge the dopamine-based theory of hypnosis and indirectly support recent neuropsychological and neurophysiological findings reporting the lack of any association between hypnotizability and focused attention abilities.

Carriers of the COMT Met/Met allele have higher degrees of hypnotizability, provided that they have good attentional control: a case of gene-trait interaction

Genetic factors may explain part of the interindividual variability in hypnotizability. A new avenue that may provide more comprehensive understanding of the phenotypic effects of genetic variations is the study of gene-trait interaction. In this study, the authors investigate the relationship of the dopamine-related COMT and the serotonin-related 5-HTTLPR polymorphisms to hypnotizability by taking individual differences in executive attention into account. Homozygosity for the COMT Met allele, putatively linked to the capability or proneness to dissociate from reality, was associated with high hypnotizability only if paired with high-attention ability. The finding can be integrated into hypnosis theory and represents a case of gene-trait interaction suggesting that investigating the effects of a gene in the context of relevant psychological traits may further elucidate gene-brain-behavior relationships.

The association between the Angiotensin-Converting Enzyme-2 gene and blood pressure in a cohort study of adolescents

BACKGROUND

The Angiotensin-Converting Enzyme-2 (ACE2) gene, located on chromosome X, is believed to be implicated in blood pressure regulation. However the few studies that have examined this association have yielded mixed results. The objective of this study was to assess the association between tag single nucleotide polymorphisms (SNPs) in the angiotensin-converting enzyme-2 gene with blood pressure and blood pressure change in adolescents.

METHODS

Participants in the Nicotine Dependence in Teens (NDIT) cohort study with blood or saliva samples and at least 3 blood pressure measurements over 5 years were included in the analytic sample (n = 555). Linear growth curve models stratified on sex and ethnicity were used to assess the association between four tag SNPs in the ACE2 gene and systolic (SBP) and diastolic blood pressure (DBP), and blood pressure change.

RESULTS

In males of European descent, rs2074192 and rs233575 were significantly associated with SBP and DBP, and rs2158083 was associated with SBP. In French Canadian males, rs233575 and rs2158083 were significantly associated with DBP. Among females of European descent, rs2074192, rs233575, and rs2158083 were significantly associated with change in SBP over 5 years.

CONCLUSIONS

This is the first study to assess the association between the ACE2 gene with blood pressure and blood pressure change in a cohort of adolescents. Results indicate that several ACE2 gene SNPs are associated with blood pressure or blood pressure change in persons of European descent. However the therapeutic potential of these SNPs should be explored.

The dopamine receptor D4 gene and familial loading interact with perceived parenting in predicting externalizing behavior problems in early adolescence: the TRacking Adolescents' Individual Lives Survey (TRAILS)

Although externalizing behavior problems show in general a high stability over time, the course of externalizing behavior problems may vary from individual to individual. Our main goal was to investigate the predictive role of parenting on externalizing behavior problems. In addition, we investigated the potential moderating role of gender and genetic risk (operationalized as familial loading of externalizing behavior problems (FLE), and presence or absence of the dopamine receptor D4 (DRD4) 7-repeat and 4-repeat allele, respectively). Perceived parenting (rejection, emotional warmth, and overprotection) and FLE were assessed in a population-based sample of 1768 10- to 12-year-old adolescents. Externalizing behavior problems were assessed at the same age and 212 years later by parent report (CBCL) and self-report (YSR). DNA was extracted from blood samples. Parental emotional warmth predicted lower, and parental overprotection and rejection predicted higher levels of externalizing behavior problems. Whereas none of the parenting factors interacted with gender and the DRD4 7-repeat allele, we did find interaction effects with FLE and the DRD4 4-repeat allele. That is, the predictive effect of parental rejection was only observed in adolescents from low FLE families and the predictive effect of parental overprotection was stronger in adolescents not carrying the DRD4 4-repeat allele.

Effects of painful stimulation and acupuncture on attention networks in healthy subjects

Pain is a subjective sensory and emotional experience, and it has been reported that many different brain regions are regulated by pain, and that pain can impact attention. Acupuncture is an important treatment component of Chinese traditional medicine, and has been used for thousands of years to treat a wide variety of conditions. Although several studies have shown that acupuncture improves consciousness, the precise impact of both acupuncture and painful stimulation on attention is unclear. Are all of the attention networks modulated, or do these stimuli act on a specific network? Is the effect of painful stimulation similar to that of acupuncture? We administered the attention network test to 30 participants (15 males) to investigate the relative efficiencies of three independent attention networks (alerting, orienting, and executive control networks) under three conditions: baseline, after painful stimulation, and after acupuncture. The degree of pain experienced was assessed on a horizontally oriented visual analogue scale. The results showed that painful stimulation and acupuncture had similar effects on the orienting and executive control networks; however, there was a significantly different effect between the three conditions on the alerting network. In conclusion, (1) painful stimulation can selectively impact attention; (2) acupuncture can also selectively impact attention; i.e., both have selective influences on the alerting and executive control networks, but not on the orienting network; (3) the effects of acupuncture and painful stimulation are not identical. The mechanisms by which painful stimulation and acupuncture influence attention warrant further research.

The DOPA decarboxylase (DDC) gene is associated with alerting attention

DOPA decarboxylase (DDC) is involved in the synthesis of dopamine, norepinephrine and serotonin. It has been suggested that genes involved in the dopamine, norepinephrine, and cholinergic systems play an essential role in the efficiency of human attention networks. Attention refers to the cognitive process of obtaining and maintaining the alert state, orienting to sensory events, and regulating the conflicts of thoughts and behavior. The present study tested seven single nucleotide polymorphisms (SNPs) within the DDC gene for association with attention, which was assessed by the Attention Network Test to detect three networks of attention, including alerting, orienting, and executive attention, in a healthy Han Chinese sample (N=451). Association analysis for individual SNPs indicated that four of the seven SNPs (rs3887825, rs7786398, rs10499695, and rs6969081) were significantly associated with alerting attention. Haplotype-based association analysis revealed that alerting was associated with the haplotype G-A-T for SNPs rs7786398-rs10499695-rs6969081. These associations remained significant after correcting for multiple testing by max(T) permutation. No association was found for orienting and executive attention. This study provides the first evidence for the involvement of the DDC gene in alerting attention. A better understanding of the genetic basis of distinct attention networks would allow us to develop more effective diagnosis, treatment, and prevention of deficient or underdeveloped alerting attention as well as its related prevalent neuropsychiatric disorders.

Polymorphism in the CHRNA4 gene is associated with rapid scene categorization performance

The CHRNA4 gene is known to be associated with individual differences in attention. However, its associations with other cognitive functions remain to be elucidated. In the present study, we investigated the effects of genetic variations in CHRNA4 on rapid scene categorization by 100 healthy human participants. In Experiment 1, we also conducted the Attention Network Test (ANT) in order to examine whether the genetic effects could be accounted for by attention. CHRNA4 was genotyped as carrying the TT, CT, or CC allele. The scene categorization task required participants to judge whether the category of a scene image (natural or man-made) was consistent with a cue word displayed at the response phase. The target-mask stimulus onset asynchrony (SOA) ranged from 13 to 93 ms. In comparison with CC-allele carriers, CT- and TT-allele carriers responded more accurately at the long SOA (93 ms) only during natural-scene categorization. In contrast, we observed no consistent association between CHRNA4 and the ANT, and no intertask correlation between scene categorization and the ANT. To validate our natural-scene categorization results, Experiment 2, carried out with an independent sample of 100 participants and a different stimulus set, successfully replicated the association between CHRNA4 genotypes and natural-scene categorization accuracy at long SOAs (67 and 93 ms). Our findings demonstrate, for the first time, that genetic variations in CHRNA4 can moderately contribute to individual differences in natural-scene categorization performance.

The role of parenting and dopamine D4 receptor gene polymorphisms in children's inhibitory control

Temperamental effortful control has important implications for children's development. Although genetic factors and parenting may influence effortful control, few studies have examined interplay between the two in predicting its development. The current study investigated associations between parenting and a facet of children's effortful control, inhibitory control (IC), and whether these associations were moderated by whether children had a 7-repeat variant of the DRD4 exon III VNTR. A community sample of 409 3-year-olds completed behavioural tasks to assess IC, and observational measures of parenting were also collected. Negative parenting was associated with lower child IC. The association between children's IC and positive parenting was moderated by children's DRD4 7-repeat status, such that children with at least one 7-repeat allele displayed lower IC than children without this allele when positive parenting was lower. These effects appeared to be primarily influenced by parent support and engagement. Results extend recent findings suggesting that some genetic polymorphisms may increase vulnerability to contextual influences.

The impact of passive hyperthermia on human attention networks: an fMRI study

An attention network test (ANT) provides a behavioral measure of the efficiency of the three attention networks (alerting, orienting and executive networks) within a single task. In the present study, we investigated the effect of passive hyperthermia on the attention network with event-related functional magnetic resonance imaging (fMRI). The behavioral results showed that passive hyperthermia of 50 °C and 40% relative humidity impaired the executive function, but showed no effect on the alerting and orienting networks. The fMRI results showed that: (i) passive hyperthermia enhanced the activity in the right superior frontal gyrus and depressed the activity in the right middle occipital gyrus, left inferior parietal lobule and left culmen in the alerting network, (ii) passive hyperthermia enhanced the activity in the temporal lobe and depressed the activity in the frontal lobe, parietal lobe and occipital lobe in the orienting network, and (iii) passive hyperthermia enhanced the activity in the dorsolateral prefrontal cortex but did not affect the activity in the anterior cingulate. We concluded that passive hyperthermia impaired executive function, especially the efficiency of resolving conflict and the negative effects of passive hyperthermia on alerting and orienting were overcome through variant regional brain activation.

Attention network impairments in patients with focal frontal or parietal lesions

Recently, research on attention has focused on 3 networks that are linked to separate brain regions, i.e. orienting, alerting, and executive control. The attention network test (ANT) is one of the methods to measure the three attention functions. However, neuropsychological investigations have not examined the anatomical disassociation of different attention networks with the same task. We compared the efficiencies of the 3 networks between brain-damaged patients (27 frontal lesions, 20 temporal lesions, and 21 parietal lesions) and healthy controls (N=58) with ANT. Comparing the brain damaged group with the normal controls, a reduced efficiency of the executive network was found in patients with frontal lobe and parietal lobe injuries, and there was also a deficit in the orienting network in patients with parietal lobe injuries. Analysis of lateralization indicated the right hemisphere superiority to the alerting system. The present study found that the three attentional networks were selectively impaired following brain damage which affected different areas in the brain.

The therapeutic benefits of perceptual learning

The modern field of perceptual learning addresses improvements of sensory and perceptual functioning in adult observers and provides powerful tools to ameliorate the effects of neurological conditions that involve a sensory or attentional deficit. While the sensory systems were once thought to be plastic only during early development, modern research demonstrates a great deal of plasticity in the adult brain. Here we discuss the value of perceptual learning as a method to improve sensory and attentional function, with a brief overview of the current approaches in the field, including how perceptual learning can be highly specific to the training set, and also how new training approaches can overcome this specificity and transfer learning effects to untrained tasks. We discuss these in the context of extant applications of perceptual learning as a treatment for neurological conditions and how new knowledge mechanisms (including attention, exposure based learning, reinforcement learning and multisensory facilitation) that allow or restrict learning in the visual system can lead to enhanced treatment approaches. We suggest new approaches that integrate multiple mechanisms of perceptual learning that promise greater learning and more generalization to real world conditions.

The impact of orienting attention in fast task-irrelevant perceptual learning

Task-irrelevant perceptual learning (TIPL) refers to the phenomenon where the stimulus features are learned when they are consistently presented at behaviorally relevant times (e.g., with task targets or rewards). Studies on the role of attention in TIPL have found that attention negatively impacts this type of learning; however, these studies involved stimuli that were completely irrelevant to the subjects and that, when noticed, were distracting to the subjects' task. Here, we asked whether attention would have a beneficial impact on learning in the case where the target-paired stimuli were relevant to a secondary task that subjects were required to perform. We conducted three experiments in adult subjects, using the fast-TIPL paradigm (which allows one to study TIPL with as little as a single trial of exposure). The results from Experiments 1 and 2 showed that fast-TIPL occurred for the target-paired stimuli but that the manipulation of attention increased performance for stimuli presented after the target. Experiment 3 was conducted to address whether the direction of attention positively or negatively impacted fast-TIPL and to better control for the effects of attention. The results of this experiment demonstrate that in the case of fast-TIPL, exogenously directed attention aids in the memorization of target-paired stimuli. Overall, our results demonstrate that attention operates in a beneficial manner in fast-TIPL, where the target-paired stimuli are relevant to a secondary task that subjects perform.

Enhancement from targets and suppression from cues in fast task-irrelevant perceptual learning

Task-irrelevant perceptual learning (TIPL) refers to the phenomenon where the stimulus features of a subject's task are learned when they are consistently presented at times when behaviorally relevant events occur. In this article, we addressed two points concerning TIPL. First, we address the question, are all behaviorally relevant events equal in their impact on encoding processes? Second, we address the hypothesis that TIPL involves mechanisms of the alerting attentional system. Two experiments of fast-TIPL were conducted in which the attentional state of participants was manipulated by using an alerting cue (visual or auditory) that informed participants of the arrival of an upcoming target. Images were presented with task-related stimuli (cues, targets and distractors) and subjects were tested on their memory of those images. Results indicate that memory for target-paired images was enhanced and cue-paired images were suppressed relative to that of distractor-paired images. The alerting cue increased the ability to recall target-paired images presented after this cue, although this result depended on the proportion of cued trials in a session. These results demonstrate a complex interplay between task-elements and the encoding of stimuli paired with them where both enhancement and suppression of task-paired stimuli can be found depending whether those stimuli are paired with task-targets or cues.

Parenting and Child DRD4 Genotype Interact to Predict Children's Early Emerging Effortful Control

Effortful control (EC), or the trait-like capacity to regulate dominant responses, has important implications for children's development. Although genetic factors and parenting likely influence EC, few studies have examined whether they interact to predict its development. This study examined whether the DRD4 exon III variable number tandem repeat polymorphism moderated the relation between parenting and children's EC. Three hundred and eighty-two 3-year-olds and primary caregivers completed behavioral tasks assessing children's EC and parenting. Children's DRD4 genotypes moderated the relation between parenting and EC: Children with at least one 7-repeat allele displayed lower EC in the context of negative parenting than children without this allele. These findings suggest opportunities for modifying early risk for low EC.

Dopamine genes (DRD2/ANKK1-TaqA1 and DRD4-7R) and executive function: their interaction with obesity

Obesity is a multifactorial disease caused by the interaction between genotype and environment, and it is considered to be a type of addictive alteration. The A1 allele of the DRD2/ANKK1-TaqIA gene has been associated with addictive disorders, with obesity and with the performance in executive functions. The 7 repeat allele of the DRD4 gene has likewise been associated with the performance in executive functions, as well as with addictive behaviors and impulsivity. Participants were included in the obesity group (N = 42) if their body mass index (BMI) was equal to or above 30, and in the lean group (N = 42) if their BMI was below 25. The DRD2/ANKK1-TaqIA and DRD4 VNTR polymorphisms were obtained. All subjects underwent neuropsychological assessment. Eating behavior traits were evaluated. The 'DRD2/ANKK1-TaqIA A1-allele status' had a significant effect on almost all the executive variables, but no significant 'DRD4 7R-allele status' effects were observed for any of the executive variables analyzed. There was a significant 'group' x 'DRD2/ANKK1-TaqIA A1-allele status' interaction effect on LN and 'group' x 'DRD4 7R-allele status' interaction effect on TMT B-A score. Being obese and a carrier of the A1 allele of DRD2/ANKK1-TaqIA or the 7R allele of DRD4 VNTR polymorphisms could confer a weakness as regards the performance of executive functions.

The effect of multisensory cues on attention in aging

The attention network test (ANT) assesses the effect of alerting and orienting cues on a visual flanker task measuring executive attention. Previous findings revealed that older adults demonstrate greater reaction times (RT) benefits when provided with visual orienting cues that offer both spatial and temporal information of an ensuing target. Given the overlap of neural substrates and networks involved in multisensory processing and cueing (i.e., alerting and orienting), an investigation of multisensory cueing effects on RT was warranted. The current study was designed to determine whether participants, both old and young, benefited from receiving multisensory alerting and orienting cues. Eighteen young (M=19.17 years; 45% female) and eighteen old (M=76.44 years; 61% female) individuals that were determined to be non-demented and without any medical or psychiatric conditions that would affect their performance were included. Results revealed main effects for the executive attention and orienting networks, but not for the alerting network. In terms of orienting, both old and young adults demonstrated significant orienting effects for auditory-somatosensory (AS), auditory-visual (AV), and visual-somatosensory (VS) cues. RT benefits of multisensory compared to unisensory orienting effects differed by cue type and age group; younger adults demonstrated greater RT benefits for AS orienting cues whereas older adults demonstrated greater RT benefits for AV orienting cues. Both groups, however, demonstrated significant RT benefits for multisensory VS orienting cues. These findings provide evidence for the facilitative effect of multisensory orienting cues, and not multisensory alerting cues, in old and young adults.

The dopamine receptor D4 7-repeat allele influences neurocognitive functioning, but this effect is moderated by age and ADHD status: an exploratory study

OBJECTIVES

Evidence suggests the involvement of the dopamine D4 receptor gene (DRD4) in the pathogenesis of ADHD, but the exact mechanism is not well understood. Earlier reports on the effects of DRD4 polymorphisms on neurocognitive and neuroimaging measures are inconsistent. This study investigated the functional consequences of the 7-repeat allele of DRD4 on neurocognitive endophenotypes of ADHD in the Dutch subsample of the International Multicenter ADHD Genetics study.

METHODS

Participants were 350 children (5-11.5 years) and adolescents (11.6-19 years) with ADHD and their 195 non-affected siblings. An overall measure of neuropsychological functioning was derived by principal component analysis from five neurocognitive and five motor tasks. The effects of DRD4 and age were examined using Linear Mixed Model analyses.

RESULTS

The analyses were stratified for affected and non-affected participants after finding a significant three-way interaction between ADHD status, age and the 7-repeat allele. Apart from a main effect of age, a significant interaction effect of age and DRD4 was found in non-affected but not in affected participants, with non-affected adolescent carriers of the 7-repeat allele showing worse neuropsychological performance. In addition, carrying the 7-repeat allele of DRD4 was related to a significantly worse performance on verbal working memory in non-affected siblings, independent of age.

CONCLUSIONS

These results might indicate that the effect of the DRD4 7-repeat allele on neuropsychological functioning is dependent on age and ADHD status.

Training the brain: fact and fad in cognitive and behavioral remediation

Putatively safe and effective for improving cognitive performance in both health and disease, products purported to train the brain appeal to consumers and healthcare practitioners. In an increasingly health-centered society, these applications constitute a burgeoning commercial market. Sparse evidence coupled with lack of scientific rigor, however, leaves claims concerning the impact and duration of such brain training largely unsubstantiated. On the other hand, at least some scientific findings seem to support the effectiveness and sustainability of training for higher brain functions such as attention and working memory. In the present paper we provide a tectonic integration and synthesis of cognitive training approaches. Specifically, we sketch the relative merits and shortcomings of these programs, which often appeal to parents who must choose between side-effect-laden medication and other less conventional options. Here we examine how neuroplasticity allows the healthy as well the impaired to benefit from cognitive training programs. We evaluate the evidence and consider whether brain training can be a stand-alone treatment or an adjunct to pharmacotherapy, outline promising future prospects, and highlight what training outcomes are plausible in line with available data. Future research would determine whether the field of brain training realizes its potential to revolutionize education and rehabilitation or withers away engulfed in controversy.