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SF | CPD: NEUROLOGY
March 2021 | Vol. 21 No. 3 www.medicalacademic.co.za
Photo credit: Shutterstock.com
This article was independently sourced by Specialist Forum.
The neuroscience of ADHD ADHD
A 2020 review found that the prevalence of attention-deficit/hyperactivity disorder (ADHD) is higher (7.47%) in children and adolescents in Africa compared to the global average (5.3%).1,2
T
his was the first review and metaanalysis of ADHD prevalence in children and adolescents in Africa, according to the authors. Similar to international trends, they found that the prevalence was greater in boys (10.60%) than in girls (5.28%).1
Definition and types of ADHD ADHD is the most common neurodevelopmental disorder in children and adolescents. According to the Diagnostic Statistical Manual fifth revision (DSM-5), ADHD is characterised by impaired levels of inattention, disorganisation, and/or hyperactivity-impulsivity.1 Inattention and disorganisation involve failure to stay on task, seeming not to listen, and losing things at levels that are not consistent with age or developmental level.1 Hyperactivity-impulsivity entails overactivity, fidgeting, inability to stay seated, intruding into other people’s activities, and inability
to wait. Symptoms are excessive for age or developmental level.1
Types of ADHD The DSM-5 differentiates between the following types of ADHD:1 » ADHD-I (predominantly inattentive): Characterised by maladaptive levels of inattention, but not hyperactivity–impulsivity » ADHD-HI (predominantly hyperactive– impulsive type): Characterised by maladaptive levels of hyperactivity– impulsivity, but not inattention » ADHD-C: Characterised by significant symptoms of both inattention and hyperactivity–impulsivity. Whilst international studies show a predominance of ADHD-I, followed by ADHD-C and ADHD-HI, the authors of the African systemic review found that ADHD-I was most common subtype of ADHD in Africa, followed by ADHD-HI and ADHD-C. ADHD-I subtype is the most prevalent subtype in
both males and females, while evidence suggest that all three subtypes are prevalent among males.1 Table 1: Prevalence of ADHD subtypes according to gender1 Subtype
Boys
Girls
ADHD-I
4.05%
2.21%
ADHD-C
3.62%
1.5%
ADHD-HI
3.61%
1.52%
Not ‘only’ a behaviour disorder Numerous studies have shown that ADHD is not ‘only’ a behavioural disorder, write Boshomane et al. In essence, ADHD is a complex cognitive disorder, which involves impairment of executive functions (EFs), also called executive or cognitive control. 2,4 One definition of EFs is: ‘A product of the co-ordinated operation of various processes to accomplish a particular goal in a flexible manner’. EFs are vital to manage intellectual resources. Together with metacognition, they play a key role in how we consciously regulate
