The term comorbidity is of questionable value in reference to developmental disorders: data and theory

Area of Science:

• Neuroscience
• Developmental Psychology
• Psychiatry

Background:

• Increasing research highlights symptom overlap in developmental disorders.
• The term "comorbidity" presumes independent causes, which may be inaccurate.
• Discrete diagnostic categories may not reflect real-world presentations.

Purpose of the Study:

• To critically evaluate the concept of comorbidity in developmental disorders.
• To investigate the extent of symptom overlap among seven common childhood disorders.
• To propose alternative explanations for co-occurring developmental deficits.

Main Methods:

• Evaluated 179 school-age children using rigorous research criteria for seven disorders.
• Included reading disability (RD), attention-deficit/hyperactivity disorder (ADHD), developmental coordination disorder (DCD), oppositional defiant disorder (ODD), conduct disorder (CD), depression, and anxiety.
• Analyzed the rates of individuals meeting criteria for two or more diagnoses.

Main Results:

• 50% of the sample met criteria for at least two diagnoses.
• Children with ADHD had a higher risk of a second diagnosis compared to those with RD.
• High overlap rates challenge the adequacy of the comorbidity concept.

Conclusions:

• The concept of comorbidity is insufficient to explain overlapping developmental disorders.
• Atypical brain development is proposed as a unifying explanatory framework.
• Rethinking diagnostic categories is necessary for a more accurate understanding of developmental challenges.