Compared to other killers from a public health standpoint, ADHD is bad. Smoking, for example, reduces life expectancy by 2.4 years, and if you smoke more than 20 cigarettes a day you’re down about 6.5 years. For diabetes and obesity it’s a couple of years. For elevated blood cholesterol, it’s 9 months. ADHD is worse than the top 5 killers in the U.S. combined.
Having ADHD costs a person nearly thirteen years of life, on average. Barkley adds, And that’s on top of all the findings of a greater risk for accidental injury and suicide…About two-thirds of people with ADHD have a life expectancy reduced by up to 21 years.
This is from Edward M. Hallowell and John J. Ratey in their book ADHD 2.0