ADHD is a neurodevelopmental disorder that begins in childhood and, for approximately 75% of children with ADHD, continues into adolescence, and over 50% continue to experience it in adulthood (1).  It is characterized by a persistent pattern of inattention and/or hyperactivity and impulsivity, and there are three different subtypes, or presentations, each with its own set of symptoms.  The three types of ADHD are Predominantly Inattentive, Predominantly Hyperactive/Impulsive, and Combined ADHD.

Predominantly Inattentive Presentation

This is commonly referred to as ADD and  involves difficulty in paying attention.  Symptoms included in this type include failing to give close attention to detail or making mistakes, difficulty sustaining attention, especially on tasks that are boring or complex that require sustained mental effort, and difficulty with planning, organizing, and following instructions.  Other symptoms include being easily distracted, in particular when they are spoken to directly where they may appear to not be listening, frequently losing necessary items for tasks and activities, and forgetfulness in daily activities. Individuals with symptoms of inattention often report a tendency to procrastinate and leave things until the last minute, for example, when deadlines force them to act.  Hyper-focus can also be an issue which is the term that refers to becoming so engrossed in things that are enjoyable and stimulating, such as video games, that it is at the expense of all else.  Girls are more frequently diagnosed with this type, and often later in life due to it being less obvious and more difficult to recognise by parents and teachers.  To be diagnosed with this type of presentation, for adolescents, over the age of 17, and adults, a minimum of 5 symptoms must be present for at least 6 months, from before the age of 12, and cause significant impairment in daily life.

Predominantly Hyperactive/Impulsive Presentation

This is the least common but the most recognised presentation of ADHD due to the obvious and often disruptive nature of hyperactivity and impulsivity seen in childhood.  Individuals with this presentation often have difficulty remaining still for any length of time, often fidget with their hands or feet, or squirm in their seat.  As children, they often run around or climb more than others however, as they become older, the symptoms may change over time and symptoms of hyperactivity become less.  Adolescents and adults often report that they feel restless and as though they are driven by a motor, and become agitated and bored easily.  Other symptoms include talking excessively, blurting out answers before the question has been completed, difficulty awaiting their turn, and interrupting others.  Overspending, overeating, and substance abuse can also become a problem for individuals who struggle with  poor impulse control.  As with the predominantly inattentive presentation, adolescents and adults must have 5 or more symptoms to meet the criteria for a diagnosis of ADHD Hyperactive/Impulsive presentation.


ADHD, Combined Presentation

This is the most common type of ADHD.  Individuals who meet the criteria for both inattentive and hyperactive/impulsive types are diagnosed as having this presentation.  



There is, as yet, no exact known cause of ADHD however, several factors have been identified as possible causes.  These include:


  • Genetics:  In the majority of cases there is a strong genetic link, with approximately 35% of children with ADHD have a parent or sibling who also has ADHD (2).  Frequently, a parent will seek an assessment for ADHD following their child having received a diagnosis, realising they also have struggled with similar problems throughout their life.


  • Differences in the Brain:  Research has found certain areas of the brain are smaller and develop slower in those with ADHD.  Also, other studies have found lower levels of the brain chemicals dopamine and norepinephrine in areas of the brain that control and regulate behaviour, emotions, working  memory, thinking, planning, and organizing (3).  Brain injuries, caused by trauma or illness, can also cause ADHD symptoms.


  • Environment: Other causes identified include substance use during pregnancy, i.e. exposure to nicotine and alcohol, exposure to high levels of lead during infancy and early childhood, and low birth weight (1).



ADHD is associated with the greatest range of comorbidities, with studies reporting that the majority of adults with ADHD have at least one other disorder.  The most common disorders seen in adults with ADHD include depression, anxiety, and substance use disorders.  When ADHD is undiagnosed or untreated, adults often report significant problems in their lives, affecting them academically, at work, and in their relationships.  Common problems include difficulty managing day to day activities such as paying bills, completing chores, forgetting appointments, inconsistent performance at school or work, leaving things until the last minute, and always being in a rush, losing or quitting jobs frequently, and having a sense of underachievement.  Unsurprisingly, feeling frustrated, stressed, and overwhelmed are frequent emotions which affect relationships and one’s self-esteem.  



An assessment for ADHD involves meeting with someone trained and qualified, and who has experience in ADHD, such as a psychologist, physician, or social worker.  A comprehensive evaluation includes conducting a detailed history of current and childhood symptoms from the individual as well as other sources, such as a parent or spouse, completion of symptom checklists, standardised behaviour rating scales for ADHD, and screening for other psychiatric disorders that can mimic, and be mistaken for ADHD.  


It is important to remember that ADHD is not something that starts in adulthood. Adults who suspect they may have ADHD must have experienced symptoms since before the age of 12 years and cause significant impairment in their life.   


If you think you may be suffering from ADHD and would like to explore this further, please contact me to arrange a free consultation to briefly discuss how I could be of help to you.



  1. Davids E, Gastpar M. Attention deficit hyperactivity disorder and borderline personality disorder. Progress in Neuro-Psychopharmacology and Biological Psychiatry 2005; 29:865-877.

  2. Blum, Kenneth, Amanda L. Chen, et al. "Attention-Deficit-Hyperactivity Disorder and Reward Deficiency Syndrome." Neuropsychiatric Disease and Treatment 4.5 (2008): 893–918. NCBI. Web.

  3. Biederman J. Attention-Deficit/Hyperactivity Disorder: A selective overview. Biol Psychiatry 2005; 57:1215-1220.

  4. "What Is Attention Deficit Hyperactivity Disorder?" National Institute of Mental Health. Web.