Symptoms across the Life-Span
It is important to note that the inattentive symptoms are more consistent across the lifespan, whereas, impulsivity and hyperactivity may become internalized or manifest differently in older adolescents and adults.
For example, the hyperactive child who is constantly in motion, may become the chronically restless adult, who cannot wait for others, speeds while driving, and is uncomfortably doing anything slowly and systematically. Overt motor activity may become verbal hyperactivity; they may often blurt things out and make inappropriate comments. Another issue is the child who impulsively leaves their seat during class, may become the reckless adult, who quits their job on a whim, spends money without thinking, is unprepared for meetings, or has difficulty resisting temptation.
Authors of the article: Kate Carr-Fanning and Conor Mc Guckin, the School of Education, Trinity College Dublin, 2012