Saturday, 10 November 2012

The pediatric ADHD numbers

In amongst the various studies which I have a tendency to read, quite a lot of column inches seem to have been dedicated to the prevalence of attention-deficit hyperactivity disorder (ADHD) in one sense or another.

Counting @ Wikipedia 
Take for example the quite recent paper by Hanson and colleagues* estimating the rate of ADHD in cases of pediatric and adolescent autism spectrum disorder.

Out of over 1500 children included for analysis, they detected comorbid ADHD (clinically significant levels of ADHD symptoms) in 16% of their cohort according to parental report and 2% when both parent and teacher reports were combined.

Other studies have detailed rather larger effects in terms of ADHD comorbidity rates as per the study by Pondé and colleagues** (53%) and similarly from Sinzig and colleagues*** (53% also) based on more direct observations and analysis.

Whilst I could go on talking about the overlap and comorbidity of ADHD in autism and the potentially lower quality of life associated with having the two conditions****, I'm more specifically drawn to the various prevalence rates for pediatric ADHD alone in this post. Obviously I can't possibly include every single paper on this topic, so there is a degree of cherry-picking related to this list of papers detailing meta-analyses with a focus on the more recent (2012) works in this area:

  • Catalá-López and colleagues***** (open-access) reported results from a meta-analysis of studies based in Spain on pediatric ADHD prevalence. On the basis of an analysis based on over 13,000 participants, they estimated a pooled prevalence of about 7%.
  • Bakare****** similarly reported meta-analysis results on ADHD prevalence in Africa. Estimates based on nine prevalence studies undertaken throughout the continent suggested a figure anywhere between 5.4% and 8.7% in school-aged children.
  • Willcutt******* with yet another meta-analysis, came up with an estimate of between 5.9% - 7.1% in children/adolescents.

I think on the basis of this snapshot of evidence you can perhaps see a pattern emerging suggestive of the fact that between 5-8% of children and young adults present with clinically verifiable ADHD across the globe. I also think you can perhaps see the disparity between ADHD presentation alone (seemingly alone) and that compared with ADHD comorbid to autism. Indeed very much like the increasing body of work on schizophrenia and autism, a diagnosis of autism seems to be a magnet for quite a few other comorbidities which I dare say probably play some role in overall quality of life and symptom presentation.

I've not covered adult ADHD and the various data on prevalence there (see this review by Simon and colleagues******** open access). Perhaps fodder for a future post alongside some chatter on potential correlates and outcomes********* and just what impact pediatric ADHD can have into adulthood.


* Hanson E. et al. Brief report: prevalence of Attention Deficit/Hyperactivity Disorder among individuals with an autism spectrum disorder. J Autism Dev Disord. October 2012.

** Pondé MP. et al. Frequency of symptoms of attention deficit and hyperactivity disorder in autistic children. Arq Neuropsiquiatr. 2010; 68: 103-106.

*** Sinzig J. et al. Attention deficit/hyperactivity disorder in children and adolescents with autism spectrum disorder: symptom or syndrome? J Atten Disord. 2009; 13: 117-126.

**** Sikora DM. et al. Attention-Deficit/Hyperactivity Disorder symptoms, adaptive functioning, and quality of life in children With autism spectrum disorder. Pediatrics. 2012; 130: S91-S97.

***** Catalá-López F. et al. Prevalence of attention deficit hyperactivity disorder among children and adolescents in Spain: a systematic review and meta-analysis of epidemiological studies. BMC Psychiatry. 2012; 12: 168.

****** Bakare MO. Attention deficit hyperactivity symptoms and disorder (ADHD) among African children: a review of epidemiology and co-morbidities. Afr J Psychiatry (Johannesbg). 2012; 15: 358-361.

******* Willcutt EG. The prevalence of DSM-IV Attention-Deficit/Hyperactivity Disorder: a meta-analytic review. Neurotherapeutics. 2012; 9: 490-499.

******** Simon V. et al. Prevalence and correlates of adult attention-deficit hyperactivity disorder: meta-analysis. Br J Psychiatry. 2009; 194: 204-11.

********* Ebejer JL. et al. Attention deficit hyperactivity disorder in Australian adults: prevalence, persistence, conduct problems and disadvantage. PLoS One. 2012; 7: e47404.

---------- Hanson E, Cerban BM, Slater CM, Caccamo LM, Bacic J, & Chan E (2012). Brief Report: Prevalence of Attention Deficit/Hyperactivity Disorder Among Individuals with an Autism Spectrum Disorder. Journal of autism and developmental disorders PMID: 23065101