The co-occurrence of Attention-Deficit/Hyperactivity Disorder and mathematical difficulties: An investigation of the role of basic numerical skills.

Background: Attention-deficit/hyperactivity disorder (ADHD) and dyscalculia, also called mathematics disorder, frequently co-occur, yet the etiology of this comorbidity is poorly understood.

Aims: This study investigated whether impairments in the understanding of numbers and magnitudes (basic numerical skills) are a unique risk factor for mathematical difficulties (MD) or a shared risk factor that could help to explain the association between ADHD and MD.

Methods And Procedures: Basic numerical skills were assessed with eight subtests in children (age 6-10 years, N = 86) with clinically significant ADHD symptoms and/or MD and typically developing children (control group).