ADHD has always been considered a children's disorder, but increasingly in the last 25 years, adults have been diagnosed and medicated for this problem. By definition, this disorder cannot appear suddenly in adults. Rather, if an adult is newly diagnosed with ADHD, the syndrome is viewed as the adult component of a childhood disorder that was never diagnosed. Although symptoms can be caused by other events such as a head injury, hyperthyroidism (high levels of thyroid hormone) or seizure disorders, true ADHD appears during early childhood.
Some individuals with adult AD/HD had more severe symptoms as children that persisted across time. Others (e.g., individuals who are very bright) may have found ways to compensate for their symptoms when they were young, but experience more challenges as they tackle living independently, pursuing a career, raising a family, and other common adult life stages.
ADHD significantly interferes with adults' ability to function in all arenas of their lives; work, home, school, and social interactions. The most common negative outcome of adult ADHD is underachievement. As adults, these individuals are often better able than children to recognize that they are different than others. However some people who have lived with ADHD their entire lives may not realize that these symptoms are indicative of a mental disorder, rather than a problem with motivation, trying hard, or any other negative comments that they may have heard throughout their lives.
Age of onset
According to DSM diagnostic criteria, ADHD develops in childhood, with at least some symptoms present prior to age 7. Estimates of children whose symptoms continue into adulthood range up to 60%.
Prevalence rates for adults with ADHD are not as clear as they are for children, but estimates suggest that 1 to 5% of American adults have some form of the disorder, including people whose symptoms are significantly reduced, but not fully in remission (i.e., have not disappeared completely). Although more males than females have the disorder in childhood, the numbers seem to even out by adulthood.