ADHD | What Is Happening Inside the Brain of Someone with ADHD?

Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder characterized by persistent patterns of inattention and/or hyperactivity-impulsivity that interfere with functioning or development. It is not a matter of willpower or a character flaw. The disorder manifests in three primary forms, known as presentations. The first is the Predominantly Inattentive Presentation, where individuals struggle with sustaining attention, organizing tasks, and following through on instructions. They are often forgetful in daily activities and easily distracted by external stimuli. The second is the Predominantly Hyperactive-Impulsive Presentation, which is marked by excessive physical movement, such as fidgeting or an inability to stay seated, and impulsive behaviors, like interrupting others or making hasty decisions without considering the consequences. The third is the Combined Presentation, where an individual exhibits a sufficient number of symptoms from both the inattentive and hyperactive-impulsive categories. The specific presentation can change over a person's lifetime as symptoms evolve with age and environmental demands.

The core of ADHD lies in the brain's structure and neurochemistry. Two elements are critical: the prefrontal cortex and the neurotransmitter dopamine. The prefrontal cortex is the brain's executive control center, responsible for regulating attention, planning, decision-making, and moderating social behavior—a set of skills known as executive functions. In individuals with ADHD, this brain region often shows delayed maturation and reduced activity. Dopamine is a chemical messenger crucial for the brain's reward and motivation systems; it plays a significant role in how we experience pleasure and maintain focus. The prevailing theory is that the dopamine system in the ADHD brain is inefficient. This dysregulation means that the signals related to reward and focus are not transmitted effectively, making mundane tasks feel unengaging and difficult to start or complete, while novel and highly stimulating activities can capture attention intensely, a phenomenon sometimes referred to as hyperfocus.

ADHD does not suddenly develop in adulthood. It is, by definition, a neurodevelopmental disorder, which means its origins are in childhood, and symptoms must be present before the age of 12 for a formal diagnosis. However, it is common for the disorder to be overlooked or misdiagnosed during childhood. This is particularly frequent in individuals with the inattentive presentation, who may be less disruptive and whose struggles might be misinterpreted as laziness or lack of intelligence. In adulthood, the demands of higher education, career, and family management can overwhelm coping mechanisms that were sufficient in a more structured childhood environment, leading to the symptoms becoming more apparent and problematic, which prompts the individual to seek a diagnosis for the first time.

ADHD presentation varies significantly between men and women, largely due to a combination of neurobiological differences and societal expectations. Historically, the diagnostic model for ADHD was based on research in young, hyperactive boys. As a result, boys are more frequently diagnosed with the hyperactive-impulsive type. Girls and women, on the other hand, are more likely to present with inattentive symptoms. These include being easily distracted, disorganized, and forgetful. Because these symptoms are less outwardly disruptive, they are often missed by parents and teachers. Consequently, women with ADHD are often diagnosed later in life and may also have developed comorbid conditions like anxiety and depression as a result of years of misunderstood struggles.

Rejection Sensitive Dysphoria (RSD) is not a formal diagnosis but is a term used to describe an extreme emotional sensitivity and pain triggered by the perception of being rejected, teased, or criticized by important people in one's life. It is considered a common and debilitating aspect of ADHD. This response is not just simple emotional sensitivity; it is a severe, instantaneous, and overwhelming emotional pain that can be difficult to manage. The neurological underpinning is thought to be linked to the same dopamine dysregulation that affects attention. The brain's emotional response network becomes intensely activated by a perceived social slight, leading to either an immediate external outburst of anger or an internal collapse into a state of severe depression and hopelessness. Individuals with ADHD may develop people-pleasing behaviors or avoid social situations entirely to prevent triggering these painful episodes.