In this post, I will share with you my research findings about the association of smoking with depression and anxiety disorders. I conducted this research during my PhD and tested ~ 3000 participants in the Netherlands.
Previous research has indicated a strong association of smoking with mental illness, especially depression and anxiety disorders, and a two-way association has been found, that is, (i) people who feel depressed/ anxious normally start smoking in order to alleviate their depressed feelings, and (ii) people who start smoking subsequently develop depression and anxiety disorders.
In my research, I selected those participants (age 18-65 years) who were not depressed / anxious when they started smoking. I split the participants in 2 groups, (i) early onset smokers, those who started smoking BEFORE the age of 15 years, and (ii) late onset smokers, those who started smoking AFTER the age of 15 years.It was found that for the early-onset smokers, it took less time to develop a mental illness as compared to the late onset smokers.
I think, the reason of this association might be that the young brain is still under development and may be more likely to be affected with nicotine.
If you want to read in detail, you can read my article here