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Are Adults Underdiagnosed Because of Overlapping Disorders? 

Yes, adult ADHD underdiagnosis comorbidity is a real and persistent issue. Many adults live with overlapping disorders like anxiety, depression, or bipolar disorder, which can mask or mimic ADHD symptoms in adults. As a result, ADHD often goes unrecognised or is mistakenly treated as something else. 

The symptoms of adult ADHD difficulty concentrating, restlessness, emotional regulation issues often overlap with other mental health conditions. When a person presents with these signs, clinicians may focus on the most obvious or familiar diagnosis, leading to ADHD misdiagnosis or complete oversight of ADHD altogether. 

How Overlapping Disorders Impact ADHD Diagnosis 

Here’s why adult ADHD underdiagnosis comorbidity is so common: 

Symptom crossover  

Trouble focusing or mood swings can occur in both ADHD and mood disorders, making it difficult to distinguish the root cause. 

Diagnostic bias  

Many healthcare professionals are more familiar with anxiety and depression in adults than they are with ADHD symptoms in adults. 

Treatment masking  

Medications or therapy aimed at one condition may reduce symptoms, unintentionally hiding signs of co-occurring ADHD. 

In conclusion, this complexity can delay proper diagnosis and treatment, leaving adults without full support for the challenges they’re facing. Recognising how overlapping disorders affect ADHD diagnosis is key to closing the gap in adult care. 

Visit providers like ADHD Certify for personal consultations and expert guidance tailored to your unique situation. 

For a deeper dive into the science, diagnosis, and full treatment landscape, read our complete guide to Overdiagnosis vs. Underdiagnosis in ADHD.  

Avery Lombardi, MSc, author for my patient advice - mypatientadvice.co.uk

Avery Lombardi, MSc

Author

Avery Lombardi is a clinical psychologist with a Master’s in Clinical Psychology and a Bachelor’s in Psychology. She has professional experience in psychological assessment, evidence-based therapy, and research, working with both child and adult populations. Avery has provided clinical services in hospital, educational, and community settings, delivering interventions such as CBT, DBT, and tailored treatment plans for conditions including anxiety, depression, and developmental disorders. She has also contributed to research on self-stigma, self-esteem, and medication adherence in psychotic patients, and has created educational content on ADHD, treatment options, and daily coping strategies.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the author's privacy. 

Dr. Rebecca Fernandez, MBBS, author and a reviewer for my patient advice - mypatientadvice.co.uk

Dr. Rebecca Fernandez, MBBS

Reviewer

Dr. Rebecca Fernandez is a UK-trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence-based approaches such as CBT, ACT, and mindfulness-based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the reviewer's privacy.