The 2007 National Survey of Children’s Health (NCSH) found that 33% of the children with ADHD had one coexisting condition, 16% had two, and 18% had three or more (Larson 2011):
These are the most common co-occurring conditions in children and adolescents according to a study by Elia et al. (2008):
Learning & Writing Disabilities
31% to 45% of children with ADHD have a learning disability, and vice versa (DuPaul 2013).
“It is estimated that as many as one-third of those with LD also have ADHD” (NCLD 2014).
Boys with ADHD have about a 65% risk of having writing disabilities, compared to 16.5% of boys without ADHD, while girls with ADHD have a 57% risk compared to a 9.4% risk for girls without ADHD (Yoshimasu 2011).
ADHD appears to be more prevalent in children with heart disease. A study by Kraut et al. (2013) examined 13,460 children using ADHD medication and found that 2% had a preexisting heart disorder compared with 1.2% of children not using medication.
The prevalence of coexisting conditions found by the National Comorbidity Survey Replication (NCS-R) in 3,199 adults with ADHD (ages 18-44) is as follows (Kessler et al. 2006):
Obesity prevalence increases by about 70% in adults with ADHD compared to adults without ADHD. In children with ADHD, obesity prevalence increases by about 40% when compared to children without ADHD (Cortese, 2015).
Analysis of data from the Collaborative Psychiatric Epidemiology Surveys found the following association between adult ADHD and obesity (Pagoto, 2009):
Cortese, Samuele et al. (2015). Association Between ADHD and Obesity: A Systematic Review and Meta-Analysis. American Journal of Psychiatry (Ahead of Print).
Elia, Josephine et al. (2008). ADHD characteristics: I. Concurrent co-morbidity patterns in children & adolescents. Child and Adolescent Psychiatry and Mental Health, 2:15.
DuPaul, George J. et al. (2013). Comorbidity of LD and ADHD: Implications of DSM-5 for Assessment and Treatment. Journal of Learning Disabilities 46(1):43–51.
Kessler et al. (April 2006). The Prevalence and Correlates of Adult ADHD in the United States: Results From the National Comorbidity Survey Replication, American Journal of Psychiatry 163(5):71.
Kraut AA et al. (2013). Comorbidities in ADHD children treated with methylphenidate: a database study. BMC Psychiatry 13:11.
Larson, Kandyce et al. (2011). Patterns of Comorbidity, Functioning, and Service Use for US Children With ADHD, 2007. Pediatrics, 127(3):462–470.
National Center for Learning Disabilities (NCLD) (2014). The State of Learning Disabilities: Facts, Trends and Indicators, New York.
Pagoto, Sherry L. et al. (March 2009). Association Between Adult Attention Deficit/Hyperactivity Disorder and Obesity in the US Population. Obesity 17(3):539–544.
Yoshimasu, Kouichi et al. (September 2011). Written-Language Disorder Among Children With and Without ADHD in a Population-Based Birth Cohort. Pediatrics 128(3):e605–e612.