Attention-Deficit/Hyperactivity Disorder (ADHD) is a Neurodevelopmental Disorder, with symptoms that begin during childhood and can persist across the lifespan.
Not all individuals with ADHD are diagnosed as children. The symptoms of ADHD are just one piece of the diagnostic picture and often, what prompts the assessment process is when someone (a parent, teacher, spouse, employer, or the individual) recognizes the impairment that symptoms are causing in daily life.
This can happen at different ages and life stages, depending on many factors (e.g., intelligence, temperament, academic skills, family and social support, learning environments, coping strategies, and many more).
The symptoms (and related impact) of ADHD often become most apparent during times of change or transition, when the demands placed on an individual may increase (e.g., entering high school or university, entering the workforce, starting a new job or starting a family) and they experience difficulty meeting expectations or demonstrating their potential. Many individuals also pursue an Attention Assessment after a family member has been diagnosed (e.g., a child or grandchild) and they see similar traits in themselves.