Attention deficit hyperactivity disorder (ADHD), a common mental disorder in children, affects 7.2% of those aged under 18 around the world. These children may still suffer from ADHD as they age.
ADHD is diagnosed using criteria in a document known as the DSM-5. These include symptoms such as hyperactivity, inattention, and impulsivity. Researchers are increasingly aware that ADHD is also accompanied by self-control issues, which affect the ability to regulate feelings.
As an example, 2.1% of children diagnosed with ADHD also suffer from a mood disorder such as depression. 27.4% of these children have anxiety disorders. Many of these children also display verbal or violent aggression.
The previously unstudied aspects of ADHD are now providing new insights into the brain activity of someone with ADHD, raising hope for improved treatment.
ADHD can have a major impact on the mental health of a child, their wellbeing, and their educational achievement. This can also affect parents, siblings, and other children.
What is the neural connection between ADHD and emotion? In our new study, published in Nature Medicine with colleagues at Fudan University in China, we identified a general brain basis—that we call the Neuro Psychopathological Factor (NP factor)—underlying symptoms of multiple mental health disorders, from depression to ADHD.
We discovered, by combining neuroimaging data with cognitive and genetic data, that a number of mental disorders may be related to “synaptic pruning”, a genetically determined problem.
The process occurs during childhood and involves removing extra synapses. These are brain structures that assist brain cells in transmitting electrical or chemical signals.
It is possible that this problem with pruning could be the underlying reason why ADHD children often also have other mental disorders. It leads to a delayed development of our prefrontal cortex, which controls our emotions and behavior. People with ADHD may struggle to control their emotions.
A delay in the development of the prefrontal cortex could also explain why ADHD children often suffer from cognitive deficits such as difficulties with executive functions, for example, planning, self-monitoring, self-control, and working memory. Children with anxiety and depression also have these symptoms. Which is the ultimate cause of the problem?
A recent, large study of 11,876 children aged 9–12 provides an important clue. We found at the University of Cambridge that children with ADHD symptoms had cognitive deficits related to attention problems, not emotions.
Attention problems are only present in children with anxiety or depression symptoms. It seems one way to help children with ADHD and mood disorders develop cognitively is to improve their attention.
Treatments
You can also learn about ADHD by studying the side effects of the medications used to treat the condition. The most common pharmacological medication for ADHD is methylphenidate, or Ritalin.
Methylphenidate works by increasing the three chemicals that are present in the brain, namely dopamine and serotonin. Noradrenaline boosts attention and reduces impulsivity. Dopamine improves learning, motivation, working memory, and attention. Serotonin has been shown to reduce symptoms associated with anxiety and depression.
ADHD can cause delayed development of the prefrontal cortex. This is shown in blue. Wikipedia, CC BY-SA
We know quite a bit about the areas of the mind that these drugs are targeting. The dopamine system is a multi-regional brain system.
In one study, methylphenidate improved attention, which was linked to increased dopamine levels in the ventral striatum of the brain (a region associated with motivation and reward). The dopamine circuit is likely to be important in ADHD.
Another study found that methylphenidate increased blood flow in the parietal and prefrontal cortices, important areas for executive functions. This study suggests that methylphenidate can improve cognitive control. Frontal areas are associated with this.
This study also confirms our findings that ADHD is associated with delayed development of the prefrontal cortex. This makes it more difficult to exercise cognitive control.
A second study found that methylphenidate improved emotional symptoms significantly in adults with ADHD. We don’t yet know if methylphenidate works to control emotions in a top-down way via the prefrontal cortex, if it directly affects emotion processing, or if it’s a mixture of both.
It is becoming more apparent that the inability to regulate emotions is not just a co-occurring problem but a core ADHD symptom. Emotional dysregulation is a key target in treatment.
Cognitive-behavioral therapy is an effective treatment for low mood and problems with self-control. Children with ADHD should receive this treatment in combination with medication.
ADHD is on the rise.
Worldwide, the number of ADHD diagnoses is increasing. Methylphenidate prescriptions are also on the rise. According to the National Health Interview Survey (NHIS), the prevalence of ADHD in children and adolescents aged 4–17 has increased in the US over the last 20 years, from 6.1% to 10.2%.
A study in the UK estimated that the use of ADHD medication increased by nearly 800% between 2000 and 2015.
We are more distracted than ever, and we split our attention rather than focus on a single task. The prevalence of ADHD may increase in the future as coping mechanisms become less effective. People will seek help and receive a diagnosis.
