There is little evidence as to why this association exists; however, it has been hypothesized that those who are predisposed to smoking are also predisposed to suicide, that smoking causes health problems which subsequently make people want to end their life, and that smoking affects brain chemistry causing a propensity for suicide.
Premda je malo dokaza o razlozima postojanja te veze, postoji hipoteza da osobe sklone pušenju imaju predispoziciju za samoubojstvo, da pušenje izaziva zdravstvene poteškoće koje, pak, dovode do želje da si ljudi okončaju život te da pušenje utječe na kemijske procese u mozgu koji izazivaju sklonost počinjenju samoubojstva.