ADHD in Adults

The exact causes of ADHD are not fully understood, but it’s thought to come from a mix of genetics, brain differences, and life experiences. ADHD often runs in families, suggesting a hereditary component. 

Many adults do not receive a diagnosis until later in life because their ADHD symptoms were not identified or were attributed to other causes during childhood. Common reasons include:

Supportive Environment: Symptoms may be less obvious when children have strong support and structure at home or at school.

High IQ or Coping Skills: Children with high intelligence or effective coping strategies can mask difficulties, making ADHD harder to detect.

Well-Behaved or Non-Disruptive: Children who follow rules and are not disruptive may not raise concerns, even if they struggle internally.

Internalising Symptoms: Some children, particularly girls, may internalise symptoms, becoming perfectionistic, anxious, or withdrawn rather than hyperactive.

Gender Differences: ADHD affects girls and boys in similar numbers, but boys are often diagnosed earlier because they are more likely to show outwardly hyperactive or disruptive behaviour. Many girls and some boys mainly show inattentive signs or mask their difficulties making it more difficult to spot.

Parental ADHD: Parents who have ADHD or traits themselves may not recognise symptoms in their child, as behaviours can feel familiar or normal to them.

Delayed Recognition: ADHD symptoms often become more noticeable in adulthood when demands increase, such as managing work, relationships, and daily responsibilities.

In adulthood, symptoms can appear subtle, variable, or hidden by coping strategies which makes recognition more difficult:

Compensatory Support: Support from others such as a spouse, partner, or family member may take on responsibilities such as managing finances, keeping track of appointments, or handling household organisation. This can mask the individual’s difficulties, making them appear more functional than they are independently.

Well-Developed Coping Strategies: Many adults with ADHD consciously or unconsciously adapt by using reminders, alarms, or strict routines, which can disguise the underlying challenges.

High Achievement or Intelligence: Some individuals achieve academically or professionally despite significant effort, leading to the false assumption that ADHD cannot be present.

Diagnostic Over Shadowing and Co-morbidity: Sometimes ADHD can be difficult to spot as many of the symptoms overlap with other conditions this is called diagnostic overshadowing. It’s common to experience other mental health conditions that have overlapping symptoms alongside ADHD this is called co-morbidity.

Diagnostic Overshadowing and Co-morbidity

ADHD shares many symptoms with other mental health conditions, which can make it tricky to diagnose. For example, trouble focusing, restlessness, and forgetfulness can appear in both ADHD and anxiety. Similarly, difficulties with concentration, memory, or motivation may be seen in both ADHD and depression. Emotional dysregulation, impulsive behaviour, and self-harm can also occur in ADHD as well as in personality disorders.

When ADHD occurs alongside another condition, it can be harder to spot. This can be particularly challenging if a clinician has less experience with ADHD or mental health conditions in general. Subtle signs may be missed or mistaken for another disorder, which can delay diagnosis and access to the right support.

Childhood Evidence and Diagnostic Oversight

Establishing evidence of ADHD symptoms from childhood is an essential part of assessment, but this can be difficult for many adults. Parents or carers might not have recognised the signs at the time, and it can be hard to remember specific details years later. School reports can also vary a lot some include very little about behaviour or attention, which can make it seem like there was “no evidence” of ADHD in childhood.

If these factors are not carefully considered, clinicians may underestimate or overlook ADHD symptoms that were present in childhood, leading to uncertainty or missed diagnoses. National and clinical guidelines highlight that a diagnosis should not be refused solely because external childhood evidence is limited or unclear from other sources. If a person can describe their own early experiences clearly and consistently, that information can be just as valuable.

In 2013, the guidelines for diagnosing ADHD (known as the DSM-5 criteria) were updated to reflect new research and to make it easier to identify ADHD at any age. These changes also helped recognise that many people with ADHD may have been missed in childhood.

One key update was raising the age by which symptoms need to have started - from 7 years old to 12. Now, a person only needs to have shown some symptoms before age 12, and these symptoms don't need to cause major problems at the time.

For adults, the number of symptoms required for a diagnosis was lowered from six to five, making the criteria more realistic for how ADHD shows up later in life.

The update also placed some emphasis on related difficulties such as emotional dysregulation, which often go hand-in-hand with ADHD.

ADHD is often under-recognised in women as they are more likely to present as inattentive, and internalise their difficulties, leading to increased anxiety, perfectionism, or low self-esteem. Symptoms may also fluctuate or become more intense during periods of hormonal change, such as the menstrual cycle, pregnancy and the postnatal period, and menopause.

Why do ADHD Symptoms Feel Stronger During Hormonal Changes?

Hormones can have a big impact on how ADHD shows up day to day. Changes in oestrogen and progesterone levels such as during puberty, periods, pregnancy, or menopause can affect brain chemicals like dopamine and serotonin, which are linked to focus and mood. When these hormone levels fluctuate, many people notice their ADHD symptoms (like forgetfulness, restlessness, or emotional dysregulation) become more intense. Understanding this connection can help you plan ahead, adjust routines, and seek the right support when needed.

ADHD affects how the brain manages attention, impulses, and emotional control. While ADHD itself brings challenges such as distractibility, impulsivity, and restlessness, it is also commonly linked with other conditions, including addictions, anxiety, and low mood. Understanding these connections can help explain why some people with ADHD experience wider difficulties and highlight how the right support can make a real difference. 

People with ADHD are more likely to experience problems with addictive behaviours such as substance misuse, gambling, binge eating or impulsive spending. This is not about weakness or poor choices it’s rooted in the way the ADHD brain processes rewards and stimulation.

The brain’s dopamine system, which helps us feel motivated and satisfied, tends to be less active in ADHD. As a result, activities that give a quick rush of pleasure or excitement like drinking, spending, gambling, or eating can feel especially rewarding. Unfortunately, this can lead to unhealthy patterns as people try to manage boredom, stress, or emotional discomfort through these behaviours.

Impulsivity also plays a role. Acting before thinking makes it harder to stop once a behaviour starts, whether that’s “just one more drink” or another spin of the roulette wheel. Over time, this can develop into addiction if the underlying ADHD is not recognised and treated.

The Link Between ADHD and Offending Behaviour

People with ADHD often struggle with impulsivity, poor attention, and difficulty managing emotions. These challenges can sometimes lead to behaviours that increase the risk of offending, such as acting without thinking or struggling to follow rules. Research in the UK has shown that ADHD is more common among people in the criminal justice system than in the general population. Early identification, support, and appropriate treatment can reduce these risks and help individuals manage their behaviour more effectively.

Living with ADHD can be exhausting. Difficulties with organisation, concentration, and time management can lead to repeated setbacks, missed deadlines, strained relationships, or underachievement at work or school. Over time, these experiences can affect self-esteem and confidence, increasing the risk of anxiety and depression.

Many people with ADHD describe a constant sense of being “behind” or “not good enough,” which can fuel negative self-talk and worry. Emotional dysregulation, a common feature of ADHD, also means that emotions can feel intense and harder to manage. This combination often leads to periods of low mood, burnout, or chronic stress.

Many people with ADHD possess unique strengths that can be powerful assets in both personal and professional life. Creativity, curiosity, and originality often come naturally, allowing individuals to think outside the box and find fresh solutions where others might see limits.

People with ADHD can be highly energetic, enthusiastic, and passionate about the things that capture their interest, bringing focus, innovation, and drive to projects that inspire them. This intensity and adaptability can make them excellent problem-solvers and quick thinkers, particularly in fast-paced or dynamic environments.

Alongside creativity and energy, individuals with ADHD often show great resilience and empathy. Having navigated challenges related to attention and organisation, they tend to develop strong perseverance, emotional insight, and humour. Many thrive in roles that value flexibility, collaboration, and initiative. When supported with understanding, structure, and strategies that suit their strengths, people with ADHD can harness their unique way of thinking to achieve remarkable success and make meaningful contributions to their communities, workplaces, and relationships.