You may have the Hyperactive-Impulsive presentation (or the Combined one), which is relatively rare among adults. I have the other one of the three (Inattentive), and I wouldn't say it raises my impulsivity, though I guess it's hard to know. The meds literally saved my life and career, but I also almost exclusively take them when working or in lowkey social situations so it's hard to say what they might do when, like, rock climbing or whitewater boating or something.

I suppose impulsivity in terms of working on what I should be working on instead of going into some rabbit hole is a type of impulsivity, and that's certainly decreased! I wouldn't call the former state "fun" though... more like "shameful", "irrational", and "distressing". Personally -- YMMV.

Anyway: yes that's plausible, as this review found pretty strong evidence of increased mortality from injury. Still, I'd personally say it's unlikely for two major reasons:

1. Presumably most injury deaths happen to adults, which are relatively quite unlikely to have the HI presentation.

2. There's just so many plausible causes of injuries, especially in a society with cars. The inclusion of "intentional injury" also introduces a factor that's no doubt strongly corellated with socioeconomic status (i.e. being murdered/manslaughtered), another very plausible cause.