ADHD is estimated to affect around 3-5% of adults worldwide.

But what is ADHD, and how does it affect a person?

ADHD stands for attention deficit hyperactivity disorder. It’s a neurodevelopmental disorder and a life-long condition affecting the brain and its executive functioning.

In many cases, ADHD is identified in childhood. However, ADHD going undiagnosed until adulthood occurs more often than you might think. And while the symptoms of ADHD may improve with age, some people may continue to face ADHD-related challenges in their adult life.

That said, ADHD is highly-treatable. With the proper support, medication, and management strategies, adults with ADHD can flourish.

Signs and Symptoms of ADHD

Symptoms of ADHD present differently in different people. The signs of ADHD tend to be easier to observe in children compared to adults.

Research has shown that ADHD symptoms may become more internalized with age.[1] For instance, a young boy with ADHD may display obvious hyperactive behaviors, such as fidgeting, trouble sitting still, or staying quiet.

Meanwhile, an adult with ADHD may not show predominant hyperactive behaviors. Instead, they may simply feel restless all the time or struggle with patience.[1]

The signs and symptoms of ADHD can generally be divided into two categories: inattention and hyperactivity/impulsivity.

Symptoms of Inattention in ADHD

The main signs of inattentiveness in adult ADHD include the following:[2]

  • Overlooking details and making careless mistakes
  • Having trouble staying focused
  • Easily distracted by surrounding stimuli or unrelated thoughts
  • Trouble listening, even when directly spoken to
  • Failing to finish tasks, work, or chores
  • Struggling to organize tasks and activities due to poor time management
  • Avoiding tasks that need prolonged focus
  • Misplacing things needed for work or daily activities
  • Forgetting to do certain tasks, chores, or errands

Symptoms of Hyperactivity/Impulsivity

ADHD may lead to symptoms of hyperactivity and impulsivity as follows:[2]

  • Fidgeting and tapping hands or feet
  • Leaving seat when inappropriate (such as in meetings)
  • Feeling restless
  • Unable to stay quiet when needed
  • Always on the go and “difficult to keep up with”
  • Talking excessively
  • Completing people’s sentences or interrupting others in conversations
  • Struggling to wait their turn
  • Intruding into other people’s activities and conversation

The two lists above don’t cover all the possible symptoms of ADHD.

The ADHD iceberg depicts the reality of living with this disorder. The visible part of the iceberg – obvious symptoms – are part of ADHD.

However, unseen challenges, such as ADHD paralysis and time blindness, are no less real. These symptoms may be hidden beneath the water, affecting work, relationships, and mental health.

Types of ADHD

ADHD does not affect everyone in the same way, and there’s no one-size-fits-all treatment plan. However, ADHD can be split into three subtypes, each with different predominant symptoms.

  • Predominantly inattentive ADHD: This type of ADHD presents with more symptoms of inattention, such as difficulty focusing, poor organization, overlooking details, and losing important things. The individual shows enough symptoms of inattention (but not hyperactivity/impulsivity) to meet the diagnostic criteria of ADHD for at least 6 months.[2] This form of ADHD is often referred to as ADD.
  • Predominantly hyperactive/impulsive ADHD: This ADHD subtype presents with more symptoms of hyperactivity/impulsivity, such as fidgeting, talking excessively, or having trouble waiting their turn. There are enough symptoms of hyperactivity or impulsivity (but not inattention) to meet the diagnostic criteria of ADHD for at least 6 consecutive months.[2]
  • Combination type ADHD: The individual shows enough symptoms of both inattention and hyperactivity/impulsivity to meet the diagnostic criteria of ADHD for 6 or more months.[2] This is the most common type of ADHD.

Other than these three ADHD types, ADHD can also be classified based on how significantly it impacts your daily activities. In general, ADHD can be divided into the following levels:[2]

  • Mild: Just enough symptoms present to make a diagnosis. The symptoms affect the person’s daily life in minor ways.
  • Moderate: A middle ground between mild and severe.
  • Severe: Many symptoms or a few particularly severe symptoms are present. Alternatively, this diagnosis may also be made if ADHD significantly affects how the person functions in social, school, or work settings.

ADHD Causes & The Role of Genetics

Though scientists have spent decades studying the causes of ADHD, they haven’t pinpointed its exact cause yet. However, research suggests that ADHD is likely due to a number of environmental and genetic factors rather than a single risk factor or “poor parenting.”[3]

Researchers have found that ADHD is highly heritable. This means that it can run in families. Based on research, having relatives with ADHD may increase your chances of having ADHD by 2-8 times.[3]

Though there is a strong genetic link, that doesn’t mean a child will inherit ADHD.

Scientists suggest that non-genetic factors such as environmental risks and chance events (random, unpredictable occurrences) also play a part.

For example, birth complications and exposure to certain toxins (like lead) during pregnancy may impact a person’s risk of developing ADHD. Drinking or smoking during pregnancy could also be a risk factor. However, more research is needed to confirm these findings.[3]

Any of the above factors may change certain aspects of the brain. The ADHD brain tends to show differences in structure, chemistry, and function, leading to the characteristic symptoms.

To sum it up, genetic and environmental factors may affect the structure, chemistry, or function of the brain, leading to symptoms of ADHD. Furthermore, research proves that ADHD is a real medical condition that affects the brain – and not just a “made-up disorder.”

ADHD Diagnosis, Evaluation, & Rating Scales

Getting a proper diagnosis is often life-changing. It opens the door for you to get the support and treatment you need to achieve your goals.

A blood test or brain scan cannot diagnose ADHD. However, a licensed mental healthcare professional will thoroughly evaluate you by assessing your symptoms and medical history.

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), is a professional handbook that provides clear guidelines for mental health professionals to diagnose ADHD.

According to the DSM-5, the following criteria must be met for a doctor to diagnose an adult with ADHD:[2]

  • The individual has five or more symptoms in either or both categories (inattention and hyperactivity/impulsivity).
  • These symptoms appear in two or more settings, such as work, school, or social activities.
  • It is evident that ADHD interferes with the individual’s functioning in work, school, or social settings.
  • The symptoms are not better explained by another psychotic or mental health condition, such as an anxiety or mood disorder.
  • Some symptoms were present before the age of 12.

Your healthcare professional will likely ask you a semi-structured set of questions that discusses your current symptoms and relevant struggles.

They may also conduct a review to check if any mental health disorders resembling ADHD are present or if you have a co-occurring condition.

Your doctor will also check whether any symptoms of ADHD were present in your childhood.[2]

They may request to see your old school reports or talk to someone who knew you well when you were a child, like a parent or a teacher. This helps them get the necessary information to make an accurate diagnosis.

Apart from asking you questions, your doctor’s evaluation may also include an ADHD rating scale. These rating scales help to identify adults with ADHD who may benefit from treatment by measuring symptoms such as inattention, restlessness, and impulsivity.[4]

One example is the Conners’ ADHD Rating Scale, which comes in different versions, including one specifically designed for adults.[4]

ADHD Treatment and Non-Pharmacological Management

Understandably, living with ADHD can be frustrating and challenging. The best way to manage ADHD is to get medical advice and treatment from a licensed mental health professional.

The most effective type of treatment for ADHD typically involves both medication and therapy.[5]

Stimulant medications are usually the first choice treatment as they work the best for most people. This type of medication helps to increase the levels of certain chemical messengers in the brain and regulate brain activity.[5]

Non-stimulant medications are another treatment option for those who don’t respond well to stimulant medications.[5]

Apart from medications, your healthcare team may recommend non-drug management options, such as the following:

  • ADHD coaching: Working with an ADHD coach empowers you to build strategies, structures, and skills to achieve your goals in an organized and timely manner. A coach can help you stay focused on your goals and address areas that need improvement, such as time management or planning.
  • Peer support groups: ADHD support groups are a great way to connect and mingle with like-minded people, share coping strategies, and exchange advice and encouragement. The ADDA virtual support groups make it easy for you to find a community online.
  • Cognitive behavioral therapy: CBT helps promote self-regulation and healthy behaviors, restructure unhelpful thinking patterns, and build essential skills like organization and time management.[5]

ADHD Doesn’t Define What You Can Achieve

Fortunately, ADHD can be effectively treated with medications and therapy.

The first step to positive change is getting a proper diagnosis from a trained healthcare professional. Once a diagnosis is made, your physician can recommend the most suitable treatment plan based on your symptoms and medical history.

Getting the support you need helps you prepare for challenges and effectively tackle them. This brings you closer to what you want to achieve in your work, school, and relationships.

Your ADHD doesn’t have to define you, your abilities, or the goals you can accomplish!

If you’re concerned that you or a loved one may have ADHD, check out ADDA’s ADHD test for adults. This checklist of symptoms helps you better understand the challenges and symptoms of ADHD and make an informed decision on what to do next.


[1] Mörstedt, B., Corbisiero, S., Bitto, H., & Stieglitz, R. D. (2015). Attention-Deficit/Hyperactivity Disorder (ADHD) in Adulthood: Concordance and Differences between Self- and Informant Perspectives on Symptoms and Functional Impairment. PloS one, 10(11), e0141342.

[2] Substance Abuse and Mental Health Services Administration. DSM-5 Changes: Implications for Child Serious Emotional Disturbance [Internet]. Rockville (MD): Substance Abuse and Mental Health Services Administration (US); 2016 Jun. Table 7, DSM-IV to DSM-5 Attention-Deficit/Hyperactivity Disorder Comparison. Available from:

[3] Thapar, A., Cooper, M., Jefferies, R., & Stergiakouli, E. (2012). What causes attention deficit hyperactivity disorder? Archives of disease in childhood, 97(3), 260–265.

[4] Taylor, A., Deb, S., & Unwin, G. (2011). Scales for the identification of adults with attention deficit hyperactivity disorder (ADHD): a systematic review. Research in developmental disabilities, 32(3), 924–938.

[5] Kolar, D., Keller, A., Golfinopoulos, M., Cumyn, L., Syer, C., & Hechtman, L. (2008). Treatment of adults with attention-deficit/hyperactivity disorder. Neuropsychiatric disease and treatment, 4(2), 389–403.

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