Spatial Attentional Bias as a Marker of Genetic Risk, Symptom Severity, and Stimulant Response in ADHD

Abstract

Attention-deficit hyperactivity disorder (ADHD) is a heritable childhood onset disorder that is marked by variability at multiple levels including clinical presentation, cognitive profile, and response to stimulant medications. It has been suggested that this variability may reflect etiological differences, particularly, at the level of underlying genetics. This study examined whether an attentional phenotypespatial attentional bias could serve as a marker of symptom severity, genetic risk, and stimulant response in ADHD. A total of 96 children and adolescents with ADHD were assessed on the Landmark Task, which is a sensitive measure of spatial attentional bias. All children were genotyped for polymorphisms (3 0 untranslated (UTR) and intron 8 variable number of tandem repeats (VNTRs)) of the dopamine transporter gene (DAT1). Spatial attentional bias correlated with ADHD symptom levels and varied according to DAT1 genotype. Children who were homozygous for the 10-repeat allele of the DAT1 3 0 -UTR VNTR displayed a rightward attentional bias and had higher symptom levels compared to those with the low-risk genotype. A total of 26 of these children who were medication naive performed the Landmark Task at baseline and then again after 6 weeks of stimulant medication. Left-sided inattention (rightward bias) at baseline was associated with an enhanced response to stimulants at 6 weeks. Moreover, changes in spatial bias with stimulant medications, varied as a function of DAT1 genotype. This study suggests an attentional phenotype that relates to symptom severity and genetic risk for ADHD, and may have utility in predicting stimulant response in ADHD.

Another way of thinking about ADHD: the predictive role of early attachment deprivation in adolescents’ level of symptoms

“…It could also be due to a motivation deficit [58,59] or to a deficit in temporal processing [61]. Neurobiological explanations, such as the crucial role of the dopamine transporter gene have also been proposed [8]. It has nevertheless been recognized that neurocognitive factors cannot explain the whole variance in ADHD symptoms [45].…”

The Influence of Dopamine Receptor D4 Polymorphism on Resting EEG in Healthy Young Females

“…Correspondently, ADHD showed a significant bias in attention away from left space [64, 65]. It was reported that left-sided inattention (rightward bias) of ADHD predicted the treatment response to stimulants, which was further modulated by the dopamine system [66]. …”

Biomarkers in the Diagnosis of ADHD – Promising Directions

“…Concerning executive functions, the 10/10 genotype predicted better performance on the Tower of London (TOL), the self-order pointing task, and the Wechsler Intelligence Scale for Children-III (WISC-III) arithmetic and digit span subtests. Associations between a neurocognitive phenotype-spatial attentional bias and 10R allele was reported in children with ADHD [73,74]. The attentional phenotype (leftsided inattention) was related to higher symptom severity [74].…”

“…Associations between a neurocognitive phenotype-spatial attentional bias and 10R allele was reported in children with ADHD [73,74]. The attentional phenotype (leftsided inattention) was related to higher symptom severity [74].…”