Which types of ADHD are common in adults?

Attention-Deficit/Hyperactivity Disorder (ADHD) in adults often presents differently than in children. Studies have shown that the combined type, which includes both inattention and hyperactivity/impulsivity, is the most common in adults. In fact, 62% of adults with ADHD fall into this category.

Interestingly, hyperactive or impulsive behaviors, which are more noticeable in children, tend to evolve as they grow older. Adults are less likely to exhibit these hyperactive traits, but impulsivity, manifesting as restlessness and hasty decision-making, remains common. This change over time is significant, as many children with hyperactive/impulsive ADHD eventually show symptoms of the combined type in adulthood.

The combined type of ADHD not only is more common in adults but also tends to have more severe symptoms. A comparative study of ADHD subtypes showed that inattention is more pronounced in the combined subtype (ADHD-C) compared to the inattentive subtype (ADHD-I).

This difference in symptom severity can greatly impact the lives of adults with ADHD. For instance, adults with the combined type are more likely to experience educational difficulties and mental health challenges, including dysthymia and substance abuse. Additionally, the ADHD-C subtype is closely linked with antisocial behavior and its consequences.

Another crucial aspect to consider is the higher risk of other psychiatric conditions in adults with combined ADHD. This subtype is often accompanied by a variety of co-occurring disorders. Clinical assessments have shown that adults with the combined subtype of ADHD have a higher rate of conduct disorder, antisocial disorder, major depression, and even an increased incidence of psychosis. These findings underscore the complexity and the significant impact that ADHD can have on an adult's life, beyond the primary symptoms of the disorder itself.

In summary, understanding the nuances of ADHD subtypes in adults is crucial. The combined type is the most common and often comes with greater challenges, including more severe symptoms and a higher risk of additional psychiatric conditions. By recognizing these patterns, we can better support and manage ADHD in adults.