Brain lateralization and self-reported symptoms of ADHD in a population sample of adults: a dimensional approach

Abstract

Many clinical studies reported a compromised brain lateralization in patients with Attention-Deficit/Hyperactivity Disorder (ADHD) without being conclusive about whether the deficit existed in the left or right hemisphere. It is well-recognized that studying ADHD dimensionally is more controlled for comorbid problems and medication effects, and provides more accurate assessment of the symptoms. Therefore, the present study applied the dimensional approach to test the relationship between brain lateralization and self-reported ADHD symptoms in a population sample. Eighty-five right-handed university students filled in the Conners’ Adult ADHD Rating Scales and performed a lateralization reaction time task. The task consists of two matching conditions: one condition requires nominal identification for letters tapping left hemisphere specialization (Letter Name-Identity condition) and the other one requires physical and visuospatial identification for shapes tapping right hemisphere specialization (Shape Physical-Identity condition). The letters or shapes to be matched are presented in left or right visual field of a fixation cross. For both task conditions, brain lateralization was indexed as the difference in mean reaction time between left and right visual field. Linear regression analyses, controlled for mood symptoms reported by a depression, anxiety, and stress scale, showed no relationship between the variables. These findings from a population sample of adults do not support the dimensionality of lateralized information processing deficit in ADHD symptomatology. However, group comparison analyses showed that subjects with high level of inattention symptoms close to or above the clinical cut-off had a reduced right hemisphere processing in the Shape Physical-Identity condition.

Neurophysiological markers of ADHD symptoms in typically-developing children

“…Our trend-level results concerning the P3 latency is not incompatible with this assumption, but provides no robust basis for evaluating it either. However, as our sample of children did neither show the expected association in behavior nor exhibit obvious behavioral problems at school, we speculate that also children with relatively higher ADHD Index scores are able to compensate any existent neurophysiological predispositions for attentional and executive problems 64 . In contrast, when neurophysiological alterations exceed a critical level, compensation would fail and observable behavioral problems may emerge—making a diagnosis of ADHD more likely.…”

Associations between cognitive performance and sigma power during sleep in children with attention-deficit/hyperactivity disorder, healthy children, and healthy adults

“…Contrary to those findings, the ADHD group did not show such a correlation, and we even found an uncorrected negative correlation between sigma power and IQ over the left parietal cortex. A pronounced unilateral parietal dysfunction in patients with ADHD has been described in several MRI studies [61, 62] [63]. Since ADHD is defined as a neurodevelopmental disorder [19], these data underline a disturbed brain maturation which also obviously affects the relationship between sleep and intellectual performance.…”

Lisdexamfetamine Alters BOLD-fMRI Activations Induced by Odor Cues in Impulsive Children

“…In ADHD, there is great body of work considering lateralization. There is nevertheless a tendency to consider that there is a right hemisphere dysfunction modulated by comorbidities associated with the disorder (55).…”