Attention deficits in children with low performance IQ: arguments for right hemisphere dysfunction

Area of Science:

• Neuroscience
• Developmental Psychology
• Child Psychiatry

Background:

• The attentional component of cognitive functioning in children is closely linked to right hemisphere (RH) neural circuits, particularly for nonverbal attention.
• Neuropsychological studies investigate RH brain dysfunction as a potential indicator in children with learning disabilities (LD).

Purpose of the Study:

• To explore the relationship between learning disabilities, attention deficit disorder (with or without hyperactivity), and right hemisphere (RH) dysfunction.
• To differentiate between nonverbal and verbal learning disabilities and their association with attention deficits.

Main Methods:

• Studied 89 children with learning disabilities, divided into nonverbal LD (lower performance IQ) and verbal LD (lower verbal IQ) groups.
• Assessed the prevalence of attention deficit disorder (ADD) and attention deficit hyperactivity disorder (ADHD) in both LD groups.

Main Results:

• The nonverbal LD group exhibited more than double the percentage of ADD/ADHD compared to the verbal LD group.
• Evidence suggests an association between RH dysfunction and nonverbal LD, as well as between RH dysfunction and ADD.
• Despite the association, ADD and low visuospatial cognition are considered clinically dissociated functions, both largely subserved by the RH.

Conclusions:

• Nonverbal learning disabilities are strongly associated with attention deficits, pointing towards right hemisphere (RH) involvement.
• Right hemisphere (RH) dysfunction is implicated in both nonverbal learning disabilities and attention deficit disorder.
• Attention deficit disorder and impaired visuospatial cognition, while linked to the RH, may represent distinct functional deficits.