A long-running study in Wisconsin followed children who had been diagnosed as hyperactive into adulthood, checking in when they were about 27 years old (135 of 158 original cases and 75 of 81 community comparisons took part, and most were male). The team looked at emotional impulsiveness, meaning traits like impatience, quick anger, easy frustration, over-reacting, temper loss, and being touchy or easily excited.
Adults whose ADHD had persisted reported more of these emotional traits (mean 4.4) than those whose ADHD had faded (mean 2.6) or the community comparison group (mean 1.5). Emotional impulsiveness also lined up with problems in everyday life on its own, on top of attention and hyperactivity problems. Across the whole sample, inattention explained the largest share of self-rated overall impairment (38%), while emotional impulsiveness added a further 9.4% and hyperactivity-impulsivity added 2.5%. Emotional impulsiveness added its own weight in 7 of 10 major life areas.
The authors note the findings are correlational and cannot show cause, partly because much of the information came from the same people rating themselves. The group was mostly male, and preparation of the paper was partly funded by Shire Pharmaceuticals.
Source: Barkley R, Fischer M. The Unique Contribution of Emotional Impulsiveness to Impairment in Major Life Activities in Hyperactive Children as Adults. Journal of the American Academy of Child & Adolescent Psychiatry (2010). doi:10.1016/j.jaac.2010.01.019