I'm not sure we're disagreeing here? As I understand it, some people have a certain kind of distractable brain and there's an underlying brain chemistry implicated here which isn't something you develop in adulthood.
However, having this brain chemistry doesn't necessarily mean a person suffers impairments in daily life: impairments are highly situational.
I suppose - to the extent that the DSM-5 requires a fair level of impariment for someone to be diagnosed with ADHD - that it's technically correct to say people can develop this in adulthood: there it passes from a syndrome to an disorder. (Personally I feel it's kind of absurd not to have a name for the syndrome if it occurs in the absence of impariment due to life circumstances! Perhaps this will be "fixed" one day as psychology slowly becomes more quantitative.)
However, having this brain chemistry doesn't necessarily mean a person suffers impairments in daily life: impairments are highly situational.
I suppose - to the extent that the DSM-5 requires a fair level of impariment for someone to be diagnosed with ADHD - that it's technically correct to say people can develop this in adulthood: there it passes from a syndrome to an disorder. (Personally I feel it's kind of absurd not to have a name for the syndrome if it occurs in the absence of impariment due to life circumstances! Perhaps this will be "fixed" one day as psychology slowly becomes more quantitative.)
Thanks for the book suggestion!