Smoking and the course of anxiety and depression

Abstract

Smoking and nicotine dependence are associated with an onset or an increased severity of the symptoms of depression and anxiety disorders, and this association is well-established. However, the mechanisms underlying this association are not yet clear. In this thesis, we found that early-onset smokers have an early onset of an anxiety disorder. We also found that nicotine-dependent smokers have more severe symptoms of depression and anxiety than the other three groups, which are comparable in symptom severity. Moreover, the rate of improvement of symptoms in dependent smokers is slower than in the other groups. In a follow-up study with the same sample, we found that only those nicotine-dependent smokers have more severe symptoms of depression and anxiety who carry the Val66Val polymorphism of the BDNF gene. In individuals carrying the Val66Met genotype of the BDNF gene, there was no difference among the four smoking groups in symptoms severity. We further found that the levels of serum BDNF is higher in current smoking groups than in non-smoking groups. No association of nicotine dependence with serum BDNF was found. Finally, we investigated the moderating role of attentional control on smoking-related attentional bias, but no moderating effect was found. Smoking, Nicotine dependence, BDNFVal66Met, severity of depression/ anxiety, attentional control