Smoking has been associated with many psychological symptoms and psychiatric disorders (Hughes 1999; Kalman et al. 2005). One explanation of this association has been that those destined to become smokers have pre-existing or “latent” psychiatric or psychological problems and use nicotine to “self-medicate” to abate these (Markou & Kenny 2002). Several epidemiological and biological lines of evidence support this hypothesis (Markou & Kenny 2002). The above section outlined data on how nicotine could improve mood. Nicotine also reliably improves performance in non-humans (Heishman 1998) and, in preliminary studies improves Alzheimer’s (Newhouse et al. 2004) and attention-deficit disorders (Levin et al. 2001) in never-smokers. Nicotine also may alleviate cognitive defects in schizophrenia (Dalack et al. 1998). The self-medication explanation would at first appear to predict smokers should have less suicide since they are treating their depression, schizophrenia, etc with smoking. However, typically this explanation posits that nicotine is an inadequate medication, and thus, suicide is still greater in those who smoke.
