Understanding ADHD

ADHD occurs in an average of 5-7% of people worldwide. Whilst the exact cause of ADHD is unknown it is believed to result from a combination of genetic, environmental, and neurological factors. 

ADHD starts during childhood but frequently persists throughout adolescence and adulthood. It is characterised by a pattern of inattentive, hyperactive and impulsive behaviour, and is often co-morbid with other psychiatric disorders. 

Patients with ADHD may have impaired academic, executive or social functions. Research indicates the strong genetic influence on ADHD with estimated heritability of 75%. 40-50% of children with ADHD have at least one parent with ADHD and 30% have a sibling with the condition.

ADHD is a neurodevelopmental disorder – it is the result of the brain developing differently during the key stages of development before they were born or as a very young child. It is not a mental illness. Causes of neurodevelopmental conditions include genetics, trauma at birth, infectious disease, nutritional factors, physical trauma and use of antibiotics whilst the brain is developing.

ADHD is a complex Neurological Disorder characterised by differences in the structure and activity in the brain. Certain brain cells are formed differently in the ADHD brain and the extensions that connect these brain cells with each other are negatively affected. The brain compensates for these differences, but the communication between brain cells remains suboptimal.

ADHD is a disorder of Self-Regulation and Executive Function. There are consistent patterns of below-normal levels and under-functioning of the neurotransmitters Dopamine, Noradrenaline, GABA, Glutamate and Serotonin in the ADHD brain. 

Neurotransmitters are chemical messengers in the brain which play a crucial role in transmitting signals between nerve cells, impacting various cognitive and emotional processes. 

• Dopamine is vital for reward, motivation and attention.
• Serotonin is involved in mood regulation and impulse control.
• Noradrenaline is crucial for attention and response inhibition.
• GABA plays a role in calming neural activity with low levels leading to anxiety and restlessness.
• Glutamate is involved in learning and memory.

An imbalance between GABA and Glutamate impacts various cognitive functions, including self-regulation.

Researchers at The National Institute of Mental Health (NIMH) have used PET scans on adults with ADHD and found there is reduced blood flow and activity levels in these brains when they were working on thinking tasks. In addition, the white matter that carries messages between neurons, is also smaller.

There are three types of ADHD:

• ADHD predominantly hyperactive and impulsive
• ADHD predominantly inattentive, without hyperactivity (previously referred to as ADD)
• ADHD combined type (hyperactive, impulsive and inattentive)

ADHD is the most treatable of all psychiatric conditions. Managing ADHD requires a multi-modal approach of behavioural interventions, psychoeducation and sometimes medication.