ADHD Misdiagnosis: Unravelling the Confusion
Written by Dr. Simon Khela MBChB MRCGP, GMC Registered Doctor
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Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that affects attention, impulse control and executive functioning. While ADHD is often associated with hyperactive children, we now know that it affects people of all ages and genders. In fact, many adults-particularly women-are not diagnosed until later in life because their symptoms have been misunderstood or attributed to other conditions.
One of the biggest challenges in diagnosing ADHD is that many of its symptoms overlap with common mental health conditions such as anxiety, depression and bipolar disorder. Difficulties with concentration, low motivation, emotional regulation and restlessness can all occur in multiple conditions, making it difficult to identify ADHD without a comprehensive clinical assessment.
An incorrect diagnosis can have significant consequences. People may receive treatments that improve some symptoms while the underlying ADHD remains unrecognised, leading to ongoing difficulties at school, work, home and in relationships.
In this guide, we explain why ADHD is commonly misdiagnosed, which conditions it is most often confused with, how clinicians distinguish ADHD from other disorders, and when you should consider seeking an ADHD assessment in the UK.
What Is ADHD?
Attention Deficit Hyperactivity Disorder (ADHD) is a lifelong neurodevelopmental disorder that affects how the brain regulates attention, behaviour and executive functioning.
Although ADHD is often associated with hyperactivity, many people experience symptoms that are less obvious, particularly adults and women.
Common ADHD symptoms include:
• Difficulty concentrating
• Easily becoming distracted
• Forgetfulness
• Poor organisation
• Difficulty prioritising tasks
• Impulsivity
• Restlessness
• Emotional dysregulation
• Chronic procrastination
• Difficulty managing time
These symptoms usually begin during childhood, although they may not become noticeable until later in life when work, university or family responsibilities increase.
One of the defining features of ADHD is executive dysfunction, which affects the brain’s ability to plan, organise, remember information and complete tasks efficiently.
Because these symptoms overlap with many other conditions, ADHD can sometimes be mistaken for a mental health disorder rather than recognised as a neurodevelopmental condition.
Why ADHD Is Commonly Misdiagnosed
ADHD is one of the most frequently misunderstood neurodevelopmental conditions.
Many of its symptoms overlap with anxiety, depression, bipolar disorder and other conditions, meaning people are sometimes treated for the wrong diagnosis before ADHD is recognised.
Rather than focusing on a single symptom, clinicians look at:
• When symptoms first appeared
• Whether symptoms have been present since childhood
• How symptoms affect daily life
• Whether symptoms occur across different settings, such as home, school or work
• Whether another condition better explains the symptoms
This process is known as differential diagnosis and is essential for distinguishing ADHD from other conditions that may present in similar ways.
It is also important to recognise that ADHD can exist alongside other mental health conditions. Some people have both ADHD and anxiety, ADHD and depression, or ADHD and bipolar disorder, requiring treatment for more than one condition.
ADHD Misdiagnosed as Depression
Depression is one of the conditions most commonly confused with ADHD because several symptoms overlap.
Both conditions may involve:
• Difficulty concentrating
• Low motivation
• Fatigue
• Problems completing everyday tasks
• Reduced productivity
• Poor memory
However, there are important differences.
Depression is primarily a mood disorder characterised by persistent sadness, hopelessness, loss of enjoyment, changes in appetite and disrupted sleep.
ADHD, on the other hand, is characterised by lifelong difficulties with attention, organisation, impulsivity and executive functioning that usually begin in childhood.
Someone with ADHD may feel frustrated because they struggle to complete tasks despite wanting to do them, whereas a person experiencing depression often loses interest or enjoyment in activities they previously found rewarding.
It is also possible to have both ADHD and depression. Living with undiagnosed ADHD for many years can contribute to low self-esteem, chronic stress and an increased risk of developing depression.
A comprehensive assessment helps determine whether symptoms are caused by ADHD, depression or both.
ADHD Misdiagnosed as Anxiety
ADHD and anxiety disorders frequently occur together, making diagnosis more complex.
Both conditions can cause:
• Difficulty concentrating
• Restlessness
• Racing thoughts
• Sleep problems
• Feeling overwhelmed
• Irritability
The key difference lies in why these symptoms occur.
People with anxiety typically struggle to concentrate because their attention is dominated by excessive worry, fear or anxious thoughts.
People with ADHD are usually distracted by multiple thoughts, external stimuli or difficulties regulating attention, regardless of whether they are feeling anxious.
Many adults with undiagnosed ADHD develop anxiety over time as they attempt to cope with missed deadlines, forgetfulness and organisational difficulties. Our comparison of ADHD vs anxiety explains this pattern in more detail.
As a result, anxiety may be diagnosed first while the underlying ADHD remains unrecognised.
For some individuals, both ADHD and an anxiety disorder are present and require treatment.
ADHD vs Bipolar Disorder
ADHD and bipolar disorder share certain characteristics, particularly impulsive behaviour and emotional dysregulation, which can sometimes lead to confusion.
However, they are distinct conditions.
Bipolar disorder involves episodes of depression and episodes of mania or hypomania. During manic episodes, individuals may experience:
• Elevated mood
• Increased energy
• Reduced need for sleep
• Racing thoughts
• Increased confidence
• Risk-taking behaviour
These episodes occur for defined periods before mood returns to baseline or changes again.
In contrast, ADHD symptoms such as inattention, impulsivity and executive dysfunction are generally consistent throughout life rather than occurring in episodes.
Although mood changes can occur in ADHD, they are usually short-lived and triggered by events or frustration rather than prolonged mood episodes.
A specialist assessment is often required to distinguish ADHD from bipolar disorder, and in some cases both conditions may exist together.
What Else Can ADHD Be Mistaken For?
Although anxiety, depression and bipolar disorder are among the most common conditions associated with ADHD misdiagnosis, several other conditions may also present with similar symptoms.
These include:
Autism Spectrum Disorder (ASD)
ADHD and autism frequently occur together, and both can affect attention, social interaction and emotional regulation. Our guide to ADHD vs autism explains the key differences and overlaps. However, autism is characterised by persistent differences in social communication, sensory processing and repetitive behaviours.
Post-Traumatic Stress Disorder (PTSD)
People living with PTSD may experience poor concentration, emotional dysregulation, hypervigilance and sleep disturbances that can resemble ADHD.
A detailed history helps determine whether symptoms began after a traumatic event or have been present since childhood.
Sleep Disorders
Poor sleep, obstructive sleep apnoea and chronic insomnia can all cause:
• Poor concentration
• Memory difficulties
• Fatigue
• Irritability
• Reduced attention
Treating the sleep disorder may significantly improve these symptoms.
Thyroid Disorders
Both overactive and underactive thyroid conditions can affect concentration, mood, energy levels and memory.
Blood tests may be used during an assessment to rule out physical health conditions that could explain ADHD-like symptoms.
Chronic Stress and Burnout
Long-term stress and burnout may lead to forgetfulness, reduced concentration, mental fatigue and difficulty completing tasks.
Unlike ADHD, these symptoms usually develop later in life and are linked to prolonged stress rather than being present since childhood.
Why ADHD Is Frequently Misdiagnosed in Women
For many years, ADHD was considered a condition that primarily affected young boys who displayed obvious hyperactive and impulsive behaviours. As a result, many girls and women with ADHD were overlooked because their symptoms often present differently.
Women are more likely to have predominantly inattentive ADHD, where symptoms include difficulty concentrating, forgetfulness, disorganisation and internal restlessness rather than physical hyperactivity. Our full guide to ADHD in girls and women explores these symptoms in more depth. These symptoms are often less disruptive in classroom or workplace settings, making them easier to miss.
Many women also develop masking behaviours, consciously or unconsciously working harder to hide their difficulties. They may rely on extensive lists, reminders or perfectionism to compensate for executive functioning challenges. While these coping strategies can help them appear organised, they often come at the cost of exhaustion, stress and burnout.
Hormonal changes during puberty, pregnancy, the menstrual cycle and menopause can also influence ADHD symptoms, making them more noticeable at different stages of life.
Because of these factors, women are frequently diagnosed with conditions such as anxiety, depression or chronic stress before ADHD is recognised.
If lifelong attention difficulties have persisted despite treatment for anxiety or depression, an ADHD assessment may help identify the underlying cause.
ADHD Misdiagnosis in Adults
Although ADHD begins in childhood, many people are not diagnosed until adulthood.
Some adults have developed coping strategies that help them manage their symptoms, while others may have been labelled as disorganised, lazy or forgetful rather than assessed for ADHD.
As responsibilities increase through university, careers, finances and family life, these coping mechanisms may no longer be enough. Everyday demands can make ADHD symptoms much more noticeable.
Common signs of undiagnosed ADHD in adults include:
• Frequently missing deadlines
• Difficulty organising work or household responsibilities
• Forgetting appointments
• Losing important items regularly
• Difficulty starting or finishing tasks
• Chronic procrastination
• Poor time management
• Restlessness
• Emotional impulsivity
• Difficulty maintaining focus during conversations or meetings
Many adults seek help for anxiety, depression or burnout without realising that ADHD may be contributing to these difficulties.
Receiving the correct diagnosis can help individuals better understand their experiences and access appropriate treatment and support.
Erectile Dysfunction Explained
Erectile dysfunction is one of the core features of ADHD and is often responsible for many of the day-to-day challenges people experience.
Executive functions are the brain’s management system, helping us to plan, organise, remember information, regulate emotions and complete tasks efficiently.
When executive functioning is affected, people may experience:
• Difficulty planning ahead
• Poor organisation
• Forgetting instructions
• Losing track of time (time blindness)
• Difficulty prioritising tasks
• Frequently switching between activities
• Trouble completing projects
• Emotional dysregulation
• Feeling overwhelmed by simple tasks
Executive dysfunction is frequently mistaken for laziness or a lack of motivation. In reality, many people with ADHD know exactly what they need to do but struggle to begin or complete tasks because of differences in how their brain regulates attention and motivation.
Understanding executive dysfunction is often the key to recognising why ADHD may have been overlooked or mistaken for another condition.
The Impact of ADHD Misdiagnosis
Receiving an incorrect diagnosis can affect nearly every aspect of a person’s life.
Without recognising ADHD, individuals may continue to struggle with attention, organisation and emotional regulation despite receiving treatment for another condition.
Some of the consequences of ADHD misdiagnosis include:
Inappropriate Treatment
Treatments such as antidepressants or anti-anxiety medication may improve symptoms of depression or anxiety if these conditions are present, but they do not directly treat the core symptoms of ADHD.
This can leave people wondering why they continue to experience difficulties with focus, organisation and executive functioning.
Ongoing Academic and Workplace Challenges
Without appropriate support, ADHD can continue to affect performance at school, university or work.
Individuals may struggle with:
• Meeting deadlines
• Managing workloads
• Completing long-term projects
• Staying organised
• Maintaining productivity
These ongoing difficulties can impact confidence and career progression.
Emotional Wellbeing
Living for years with undiagnosed ADHD may contribute to:
• Low self-esteem
• Feelings of frustration
• Chronic stress
• Anxiety
• Depression
Many people blame themselves for difficulties that are actually related to untreated ADHD.
Relationship Difficulties
ADHD symptoms can also affect personal relationships.
Forgetfulness, impulsivity, emotional sensitivity and organisational challenges may create misunderstandings with partners, family members and colleagues, as explored in our guide to how ADHD affects adult relationships.
Receiving the correct diagnosis often helps individuals better understand these challenges and develop strategies to improve communication and daily functioning.
How ADHD Is Diagnosed in the UK
Diagnosing ADHD involves much more than completing a questionnaire.
A comprehensive assessment considers an individual’s current symptoms, developmental history and how those symptoms affect daily life.
Healthcare professionals typically assess:
• Childhood behaviour and school experiences
• Current symptoms
• Family history
• Medical history
• Mental health history
• Functional difficulties at work, education or home
Clinicians also consider whether another condition could better explain the symptoms or whether ADHD exists alongside another diagnosis.
Standardised assessment tools and structured clinical interviews are commonly used to support the diagnostic process.
Because ADHD shares symptoms with several other conditions, differential diagnosis is an essential part of every assessment.
NHS vs Private ADHD Assessment
In the UK, adults can access ADHD assessments through the NHS or private healthcare providers.
NHS Assessment
Assessment through the NHS usually begins with a referral from a GP, as outlined in NHS guidance on ADHD.
Waiting times vary considerably depending on location and can extend to several months or, in some areas, considerably longer due to increasing demand.
Private ADHD Assessment
Private assessments often provide significantly shorter waiting times, allowing individuals to receive a comprehensive evaluation more quickly. Our guide to the value of private GP-led ADHD assessment explains what this route involves.
Following diagnosis, clinicians can discuss treatment options, lifestyle strategies and, where appropriate, medication.
When choosing a private provider, it is important to ensure the assessment is carried out by appropriately qualified clinicians using recognised diagnostic criteria.
When Should You Seek an ADHD Assessment?
You may benefit from an ADHD assessment if you have experienced lifelong difficulties with attention, organisation or impulsivity that affect your education, work or relationships.
Consider seeking an assessment if:
• You have struggled with concentration since childhood.
• You frequently forget appointments or lose important items.
• Anxiety or depression treatment has not fully explained your symptoms.
• You experience significant difficulties with organisation or time management.
• A close family member has ADHD.
• Your symptoms affect your work, education or personal relationships.
• You recognise yourself in common signs of adult ADHD.
Receiving an accurate diagnosis can provide clarity, help explain longstanding challenges and allow access to evidence-based treatment and support tailored to your needs.
Final Thoughts
ADHD is a complex neurodevelopmental disorder that can present differently from person to person. Because many of its symptoms overlap with conditions such as anxiety, depression and bipolar disorder, receiving an accurate diagnosis is essential for accessing the right treatment and support.
For many adults, particularly women, years of coping with undiagnosed ADHD can lead to frustration, low self-esteem and unnecessary emotional distress. A comprehensive assessment that considers childhood history, current symptoms and the possibility of co-existing conditions can help identify the underlying cause of these challenges.
If you recognise many of the symptoms discussed in this guide or feel that previous diagnoses have not fully explained your experiences, seeking a professional ADHD assessment may provide the clarity and support you need to move forward with confidence. Read one patient’s story of finding the right ADHD treatment to see what this can look like in practice.
Book a Private ADHD Assessment
At Private Medical Clinic, we provide comprehensive ADHD assessments for adults carried out by experienced clinicians. Our assessments are designed to identify ADHD accurately while carefully considering other conditions that may present with similar symptoms.
We offer:
• Comprehensive ADHD assessments
• Short waiting times
• Experienced clinicians
• Personalised treatment recommendations
• Ongoing support where appropriate
If you are concerned that your symptoms may have been misdiagnosed or would like greater clarity about your mental health, book an ADHD assessment today and take the first step towards understanding your symptoms.
