Nicotine dependence vs. daily smoking as a meaningful variable: implications for clinical and epidemiological psychiatric studies.

Objective: As an indication of potential psychopathology, our aim was to compare, in a non-psychiatric sample, the variables associated to daily smoking with those associated to nicotine dependence. We also compared dependent and non-dependent smokers on these variables and on the age of onset of daily smoking (AODS).

Method: A sample of 290 persons aged 18 or older, recruited in a family medical clinic, were interviewed to inquire about their tobacco, caffeine, alcohol, and illegal drugs consumption, and on their practice of physical exercise. Psychiatric morbidity was assessed with the General Health Questionnaire (GHQ-28) and defined by a score>6. They also were questioned on their use of psychotropic medication and previous suicide attempt. The smokers answered the Fagerström Test for Nicotine Dependence (FTND) and the question on their age of onset of daily smoking (AODS).

Results: In comparison with non-dependent smoking, nicotine dependence was associated with current use of psychotropic medication, psychiatric morbidity, previous suicide attempt, and earlier AODS. Logistic regression analyses showed that nicotine dependence was associated with antecedents of suicide attempt and primary or lower education as well as with high caffeine use and the regular use of illegal drugs; in contrast, daily smoking showed a significant association with high caffeine use, the regular use of illegal drugs and lack of physical exercise.

Conclusions: In terms of psychopathology or behavioral disturbance-particularly attempting suicide-nicotine dependence adds significant information as opposed to the simple daily smoking, with important implications in clinical and epidemiological psychiatric studies.