Dopamine receptor D2 ( DRD2 ), dopamine transporter solute carrier family C6, member 4 ( SLC6A3 ), and catechol- O -methyltransferase ( COMT ) genes as moderators of the relation between maternal history of maltreatment and infant emotion regulation

The known and unknown about attention deficit hyperactivity disorder (ADHD) genetics: a special emphasis on Arab population

Attention deficit hyperactivity disorder (ADHD) is a clinically and genetically heterogeneous neurodevelopmental syndrome characterized by behavioral appearances such as impulsivity, inattention, and hyperactivity. The prevalence of ADHD is high in childhood when compared to adults. ADHD has been significantly advanced by genetic research over the past 25 years. However, it is logically conceivable that both genetic and/or non-genetic factors, such as postnatal environmental and social influences, are associated with ADHD phenotype in Arab populations. While genetic influences are strongly linked with the etiology of ADHD, it remains obscure how consanguinity which is an underlying factor for many genetic diseases, contributes to ADHD subtypes. Arabian Gulf Nations have one the highest rates of consanguineous marriages, and consanguinity plays an important contributing factor in many genetic diseases that exist in higher percentages in Arabian Gulf Nations. Therefore, the current review aims to shed light on the genetic variants associated with ADHD subtypes in Arabian Gulf nations and Saudi Arabia in particular. It also focuses on the symptoms and the diagnosis of ADHD before turning to the neuropsychological pathways and subgroups of ADHD. The impact of a consanguinity-based understanding of the ADHD subtype will help to understand the genetic variability of the Arabian Gulf population in comparison with the other parts of the world and will provide novel information to develop new avenues for future research in ADHD.

Mediators and moderators in the relationship between maternal childhood adversity and children's emotional and behavioural development: a systematic review and meta-analysis

Maternal experiences of childhood adversity can increase the risk of emotional and behavioural problems in their children. This systematic review and meta-analysis provide the first narrative and quantitative synthesis of the mediators and moderators involved in the link between maternal childhood adversity and children's emotional and behavioural development. We searched EMBASE, PsycINFO, Medline, Cochrane Library, grey literature and reference lists. Studies published up to February 2021 were included if they explored mediators or moderators between maternal childhood adversity and their children's emotional and behavioural development. Data were synthesised narratively and quantitatively by meta-analytic approaches. The search yielded 781 articles, with 74 full-text articles reviewed, and 41 studies meeting inclusion criteria. Maternal mental health was a significant individual-level mediator, while child traumatic experiences and insecure maternal-child attachment were consistent family-level mediators. However, the evidence for community-level mediators was limited. A meta-analysis of nine single-mediating analyses from five studies indicated three mediating pathways: maternal depression, negative parenting practices and maternal insecure attachment, with pooled indirect standardised effects of 0.10 [95% CI (0.03-0.17)), 0.01 (95% CI (-0.02 to 0.04)] and 0.07 [95% CI (0.01-0.12)], respectively. Research studies on moderators were few and identified some individual-level factors, such as child sex (e.g. the mediating role of parenting practices being only significant in girls), biological factors (e.g. maternal cortisol level) and genetic factors (e.g. child's serotonin-transporter genotype). In conclusion, maternal depression and maternal insecure attachment are two established mediating pathways that can explain the link between maternal childhood adversity and their children's emotional and behavioural development and offer opportunities for intervention.

Schoolchildren's autobiographical memory: COMT gene Val158Met polymorphism effects on emotional content and quality of first memories

Autobiographical memory is a cognitive function strongly related to emotional processing as autobiographical memory often includes emotional content. The COMT gene Val¹⁵⁸Met polymorphism is associated with both cognitive and emotional processing. COMT gene Val¹⁵⁸Met polymorphism effects on the emotional content and quality of Estonian schoolchildren's first autobiographical memories were investigated in the present study. In addition, gender effects were considered and the emotional valence of the first memory was taken into account. Schoolchildren's (N = 234) first memories were coded for valence, emotion words, specificity, and details. Girls were more likely to provide specific memories and recollections with an emotional valence than boys were. Children described memories with a positive or a negative valence in more detail than neutral memories. Interactions between the COMT gene Val¹⁵⁸Met polymorphism and gender and valence of the events were detected: Val/Met heterozygotes provided fewer details for emotional events; Val/Met heterozygote boys reported fewer details for their first memories than Val/Met heterozygote girls did; Met/Met homozygote children provided fewer evaluative details for emotional events.

DNA Methylation and Allelic Polymorphism at the Dopamine Transporter Promoter Affect Internalizing and Externalizing Symptoms in Preschoolers

The role of the dopamine transporter (DAT) in the onset and maintenance of emotional-behavioral difficulties is recognized in adults, adolescents and school-age children, whereas few studies in this field have focused on preschoolers. The study recruited 2-year old children (N = 152) in the general population assessing the possible effect of DAT methylation and allelic polymorphism on internalizing and externalizing symptoms, also exploring whether epigenetic and genetic variability interact. Our results showed that DAT methylation is significantly associated with all the dimensions of children's emotional/behavioral functioning in children carrying 10/10-3/3-8/10 polymorphisms but not in children carrying 9/10-9/9 allele repeats. Understanding the influence of genetic/epigenetic factors on maladaptive emotional/behavioral outcomes in young children, can be of great help in programming effective prevention and intervention plans and can be a valid aid to alleviate psychopathological symptoms before they crystalize into more severe clinical conditions in later life.

Children's DAT1 Polymorphism Moderates the Relationship Between Parents' Psychological Profiles, Children's DAT Methylation, and Their Emotional/Behavioral Functioning in a Normative Sample

Parental psychopathological risk is considered as one of the most crucial features associated with epigenetic modifications in offspring, which in turn are thought to be related to their emotional/behavioral profiles. The dopamine active transporter (DAT) gene is suggested to play a significant role in affective/behavioral regulation. On the basis of the previous literature, we aimed at verifying whether children’s DAT1 polymorphisms moderated the relationship between parents’ psychological profiles, children’s emotional/behavioral functioning, and DAT1 methylation in a normative sample of 79 families with school-age children (Ntot = 237). Children’s biological samples were collected through buccal swabs, while Symptom Check-List-90 item Revised, Adult Self Report, and Child Behavior Check-List/6–18 was administered to assess parental and children’s psychological functioning. We found that higher maternal externalizing problems predicted the following: higher levels of children’s DAT1 methylation at M1, but only among children with 10/10 genotype; higher levels of methylation at M2 among children with 10/10 genotype; while lower levels for children with a 9-repeat allele. There was also a positive relationship between fathers’ externalizing problems and children’s externalizing problems, only for children with a 9-repeat allele. Our findings support emerging evidence of the complex interplay between genetic and environmental factors in shaping children’ emotional/behavioral functioning, contributing to the knowledge of risk variables for a child’s development and psychological well-being.