What assessment tools help distinguish ADHD vs depression vs bipolar?

PostedNovember 20, 2025

UpdatedNovember 21, 2025

ByMy Patient Advice

Author: Harriet Winslow, BSc | Reviewed by: Dr. Rebecca Fernandez, MBBS

When symptoms such as poor concentration, fluctuating mood, or impulsivity appear together, it can be challenging to tell whether they stem from attention deficit hyperactivity disorder (ADHD), depression, or bipolar disorder. These conditions often share overlapping features, yet the underlying causes and treatments differ significantly. According to the NHS, diagnosis relies on structured assessments, detailed history-taking, and the use of validated rating tools to ensure an accurate distinction between these mental health conditions.

Understanding how clinicians tell these conditions apart

The latest NICE guidance on ADHD (NG87, 2025) recommends structured interviews such as DIVA-5 and ACE+, supported by validated questionnaires like the ASRS. Clinicians are also advised to gather corroborative information from family members, teachers, or colleagues. This helps determine whether inattentive or impulsive behaviours are lifelong traits, typical of ADHD, or episodic and mood-related as seen in depression or bipolar disorder. NICE highlights the importance of screening for mood disorders during ADHD assessment due to the high rate of comorbidity.

ADHD assessment tools and approach

Both NICE and the Royal College of Psychiatrists (CR235, 2022) recommend tools such as DIVA-5, ASRS and Conners questionnaires as part of a full clinical assessment. The NHS England ADHD Taskforce Report (2025) explains that while rating scales provide valuable structure, they must be interpreted alongside a full developmental and psychiatric history using DSM-5 or ICD-11 frameworks. This approach helps clinicians differentiate chronic ADHD symptoms from episodic patterns linked to mood disorders.

Tools used for depression and bipolar disorder

For mood disorders, NICE’s bipolar disorder guidance (CG185, 2025) recommends comprehensive psychiatric evaluation alongside validated questionnaires such as PHQ-9 and GAD-7 for depression and anxiety, and MDQ or the Young Mania Rating Scale for bipolar disorder. Evidence published in Frontiers in Psychiatry (2025) found that integrating these scales within multidisciplinary, longitudinal assessment improves diagnostic accuracy and helps clinicians interpret the course of symptoms over time.

Integrating assessment across conditions

A 2025 PubMed review reported that no single questionnaire can distinguish ADHD, depression, and bipolar disorder in isolation. The most reliable approach combines standardised rating scales, longitudinal observation, and collateral information from family or education records. According to the NHS and NICE, consistency across multiple settings and symptom timelines is key to identifying the correct condition.

Key takeaway

Validated assessment tools such as DIVA-5, ASRS, PHQ-9, GAD-7, MDQ and the Young Mania Rating Scale help guide clinical understanding, but they work best within a full psychiatric evaluation. As emphasised by NICE and the NHS, accurate differentiation depends on structured interviews, patient history, and multidisciplinary review. Using these methods together enables clinicians to distinguish ADHD from depression and bipolar disorder with greater clarity and confidence.

Harriet Winslow, BSc

Author

Harriet Winslow is a clinical psychologist with a Bachelor’s in Clinical Psychology and extensive experience in behaviour therapy and developmental disorders. She has worked with children and adolescents with ADHD, autism spectrum disorder (ASD), learning disabilities, and behavioural challenges, providing individual and group therapy using evidence-based approaches such as CBT and DBT. Dr. Winslow has developed and implemented personalised treatment plans, conducted formal and informal assessments, and delivered crisis intervention for clients in need of urgent mental health care. Her expertise spans assessment, treatment planning, and behavioural intervention for both neurodevelopmental and mental health conditions.

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.