How Does the Age of Onset Differ Between ADHD and Bipolar Disorder? 

The ADHD vs bipolar onset is an important factor in distinguishing between the two conditions, as the age at which symptoms first appear can offer valuable insights for accurate diagnosis. Understanding the onset age for both ADHD and bipolar disorder helps clinicians make a more informed assessment and guide appropriate treatment. 

ADHD Onset: Early Childhood 

ADHD typically presents in early childhood, with symptoms often becoming noticeable by the age of 3 to 7 years. According to diagnostic criteria, for an ADHD diagnosis, the symptoms of inattention, hyperactivity, and impulsivity must be present for at least six months and cause significant impairment in daily functioning. These symptoms are evident across various settings, such as home, school, or social interactions.  

Bipolar Disorder Onset: Late Childhood to Early Adulthood 

In contrast, bipolar disorder typically emerges later, often in late childhood or early adolescence, with a significant peak in onset between the ages of 15 and 19. The onset of bipolar disorder is usually marked by distinct mood episodes, including mania or hypomania (elevated mood and energy) and depressive episodes (low mood, loss of interest). According to diagnostic criteria, bipolar disorder is characterised by extreme mood changes that last for days or weeks, rather than the brief emotional fluctuations common in ADHD. 

The ADHD vs bipolar onset differs significantly, with ADHD typically presenting in early childhood and bipolar disorder emerging later, often during adolescence. Recognising these onset age patterns is crucial for accurate diagnosis and treatment. 

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 Differential Diagnosis of ADHD.

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

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.