How Can Clinicians Differentiate Between ADHD and Mood Disorders?Â
Distinguishing Attention Deficit Hyperactivity Disorder (ADHD) from mood disorders such as depression, dysthymia, or bipolar disorder can be complex. Both share overlapping symptoms, like emotional reactivity, irritability, and concentration difficulties, but differ in their duration, patterns, and neurobiological roots.
ADHD vs Mood Disorder: Core Differences
ADHD symptoms are chronic and reactive, often triggered by frustration or overstimulation, and fluctuate within hours.
Mood disorders, on the other hand, present as sustained emotional episodes lasting days or weeks, frequently unrelated to external triggers.
The Mayo Clinic explains that ADHD-related mood swings are momentary and situational, whereas depression and bipolar episodes cause global shifts in mood, energy, and motivation.
NHS & NICE NG87: Diagnostic Guidance
The NICE NG87 guideline advises clinicians to screen for anxiety or mood disorders before diagnosing ADHD.
When symptoms are atypical or episodic, referral to specialist mental health services is recommended.
Similarly, the NHS notes that persistent low mood, loss of interest, or disrupted sleep may indicate a primary mood disorder rather than ADHD.
RCPsych: Emotional Reactivity vs Mood Episodes
The Royal College of Psychiatrists (RCPsych) highlights that:
- ADHD-related emotions are brief and reactive (minutes to hours).
- Mood disorder changes are sustained and involve physiological symptoms (sleep, appetite, energy).
Neurobiological Differences
- ADHD: Linked to dopamine and noradrenaline dysregulation in the prefrontal cortex (executive and attentional control).
- Depression: Involves serotonin and HPA-axis imbalance.
- Bipolar disorder: Related to dopamine hypersensitivity and prefrontal-limbic dysfunction.
The Lancet Psychiatry (2023) found that emotional dysregulation in ADHD arises from executive control failure, while in bipolar disorder it reflects mood-cycle circuitry instability. Frontiers in Psychiatry – Emotional regulation and mood disorders
Clinical Red Flags for Mood Disorders
Clinicians should suspect a mood disorder if:
- Mood changes last days or weeks
- Sleep or appetite significantly shifts
- Energy alternates between low and high extremes
- Risky or euphoric behaviour appears without clear triggers
PubMed (2025) reports that up to 30% of adults initially diagnosed with ADHD were later reclassified as bipolar disorder due to unrecognised mood cycling. PubMed – ADHD and bipolar misdiagnosis
Treatment Priorities and Safety
The Mayo Clinic and Cleveland Clinic both emphasise stabilising mood disorders first.
Introducing stimulants before mood stability can trigger mania or worsening anxiety. Once mood is regulated, ADHD medication can be introduced gradually, often alongside CBT or DBT.
Integrated and Ongoing Care
According to NICE and RCPsych, patients with co-occurring ADHD and mood disorders benefit most from:
- Collaborative care between psychiatry, psychology, and primary care
- Psychoeducation and emotional self-monitoring
- Regular medication reviews and therapy integration
Final Takeaway
Clinicians differentiate ADHD from mood disorders by examining duration, context, neurobiology, and reactivity.
While ADHD involves chronic, reactive emotional shifts, mood disorders show sustained, internally driven episodes. Accurate diagnosis supported by NICE, NHS, and RCPsych guidance ensures safe, effective treatment and better long-term outcomes.
