Smoking, nicotine dependence and mental health among young adults: a 13-year population-based longitudinal study

To investigate prospectively the associations between daily smoking and nicotine dependence and anxiety, depression and suicide attempts. Data were from the Young in Norway Longitudinal Study. A population-based sample (n = 1501) was followed for 13 years from ages 13-27 years. Data were gathered on smoking patterns and nicotine dependence; and depression, anxiety and parasuicide. Extensive information on socio-demographic factors, parental and family conditions, parental rearing practices, educational career, conduct problems, alcohol problems and use of illegal substances was also collected. Young adults who were nicotine-dependent had clearly elevated rates of anxiety, depression and parasuicide. These rates declined after controlling for a previous history of mental health problems and potential confounding factors. After adjustment, nicotine dependence was still associated with anxiety, depression and parasuicide. There was also a significant association with later depression in the group of non-dependent daily smokers. Measures of reduced mental health did not predict later smoking initiation or the development of nicotine dependence. Mental health was reduced more seriously in nicotine-dependent smokers than in non-dependent smokers. These findings are consistent with the hypothesis that smoking, in particular nicotine dependence, influences mental health.