the only long term affect is the smoke inhalation. this alone is what seems to be negative affects of chronic smoking. however, this is more than enough to decrease performance. as for adhd, smoking will make you less anxious, but you are only drugging yourself, it doesn’t matter what way you drug yourself what you end up doing is masking symptoms. power drive helps as does eating every few hours and keeping junk food out of the diet. i have adhd too, but am managing it well now. i find i am very sensitive to food additives and when i eat clean the problems dissappear and i can manage my anxiety better. i smoke the herb too sometimes and it kills my appetite.
remember, when your body needs something it will tell you if you listen, or you can drug it out and ignore the problem like most people do.