Common Comorbidities in Comorbid Complex ADHD:

Prevalence, Age of Onset, Diagnosis, and Clinical Implications

Andrew J. Cutler, MD
Associate Clinical Professor
Department of Psychiatry
SUNY Upstate Medical University
Syracuse, New York

Dr Cutler has been compensated to discuss the clinical data in this program.
This presentation discusses comorbid complex attention‑deficit/hyperactivity disorder (ADHD)—prevalence, age of onset, diagnosis, and clinical implications.
Majority of People With ADHD Have at Least One Comorbidity
1. Majority of People With ADHD Have at Least One Comorbidity1.

Majority of People With ADHD Have at Least One Comorbidity1

Comorbid complex ADHD is very common—studies show that three‑quarters of individuals with ADHD have at least one psychiatric condition, and 80% of those individuals have more than one comorbidity.

Potential Explanations for Comorbidities in ADHD2,3

Why do people with ADHD have comorbidities? It is possible that one disorder is a precursor to the other (evolving over time). It could also be that one disorder is a risk factor for developing the other or they may have a common genetic basis.
Some comorbid disorders, such as depression and anxiety, may develop due to the impact of ADHD, making it a secondary condition. 2,3

Comorbidity Profiles Change With Age2,4-7

The comorbidity profile can change throughout the patient’s lifespan (⇱Figure 2). In children and adolescents, studies have shown a high incidence of oppositional defiant disorder (ODD), which decreases in adulthood.4 However, in adults, problems with emotional dysregulation, stubbornness, trouble managing anger, and other negative emotions are seen.8 In addition, those comorbidities that tend to be less common in childhood, such as conduct issues, anxiety, major depressive disorder (MDD), and substance use disorder (SUD), increase in incidence through adolescence and into adulthood.4
Co-morbidity Profiles Change With Age
2. Co-morbidity Profiles Change With Age2,4-7
The cumulative burden of comorbid complex ADHD evolves and accumulates throughout the patient’s lifespan.9,10 For example, although ODD is the most common comorbidity in children, CD and anxiety are also seen. The impact of these, along with ADHD, results in low self‑esteem in this age group.4,10
Moving from childhood into adolescence and adulthood, ODD and CD decrease, but criminal behaviors start to show, with antisocial personality disorder becoming more common.2,4,6,7,10 In addition, learning delays in childhood develop into complex learning difficulties in adolescence and adulthood. With this progression, patients often become demoralized and frustrated, resulting in lack of motivation and underachievement. Substance abuse comes into play, as well.4,10
Table 1. Overlapping Symptoms of ADHD and Comorbidities11

Overlapping Symptoms of ADHD and Comorbidities11

The presence of comorbidities in different age groups can complicate the diagnosis of ADHD, as symptoms of these comorbidities often overlap with symptoms of ADHD.2,11 For example, ADHD symptoms of restlessness, agitation, difficulty concentrating, and decreased attention are also seen in MDD, BPD, anxiety, SUD, and sleep disorders. Additionally, impulsivity is an ADHD symptom seen in CD, BPD, and SUD.11

Diagnosing ADHD12

Given the overlap of symptoms of ADHD and its comorbidities, what are the steps to ensure an accurate diagnosis? First, it is important to establish the diagnosis by confirming that the individual meets DSM-5 criteria for ADHD. Then, rule out alternative explanations for the symptoms. Finally, it is important to assess for comorbid conditions, which may affect the treatment of ADHD, as well as the diagnosis.12
It is important to assess for comorbid conditions, which may affect the treatment of ADHD, as well as the diagnosis.12

Differentiating Depression From ADHD2

To differentiate ADHD from depression, it is necessary to identify which symptoms of depression overlap with ADHD and which are distinct. Overlapping symptoms include loss of motivation, problems concentrating, and restlessness or irritability. If patients have any of these symptoms, it could be ADHD, depression, or both.2

Symptoms of depression that overlap with symptoms of ADHD

Characteristics of depression that are distinct from ADHD

3. Differentiating Depression From ADHD2
However, if patients only have symptoms of depression that are distinct from ADHD, such as feelings of sadness, thoughts of suicide, or changes in eating or sleeping, it is likely depression.2
Thank you for being part of this Team ADHD educational presentation.


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