“There is a strong comorbidity between mood disorders such as depression, and tobacco use disorder. The disorder is a dependence on nicotine that elicits a reaction when a person stops smoking.

In the first study of its kind, published in the journal Redox Report (2015), researchers looked at the effectiveness of N-acetylcysteine (NAC) in helping people quit smoking, and whether reduced tobacco use is associated with a concomitant decreased severity of depression. The 12-week double-blind randomised controlled trial compared the effectiveness of 3g of NAC daily with placebo.

The study showed that more than double the number of participants taking NAC were able to quit smoking compared to those taking placebo. In those who did not quit, the number of cigarettes smoked on a daily basis more than halved. The effect was most apparent after week eight of NAC supplementation. Study authors also measured exhaled carbon monoxide which was almost 150% less in the NAC group compared to placebo.

The mechanism is thought to be NAC’s role in activating the activity of the cystine–glutamate antiporter, resulting in increased activation of metabotropic glutamate receptors on inhibitory neurons which facilitates dopamine release. In this way, craving and reward behaviours are modulated. NAC is also thought to improve the damage caused by tobacco smoke exposure such as oxidative damage to the lungs.

Another interesting finding was the significant reduction in the Hamilton Rating Scale for Depression (HDRS) amongst NAC users. Depression and tobacco use are comorbidities – 40-60% of those with depression are estimated to have tobacco use disorder. It is thought that nicotine has short term antidepressant effects by increasing the metabolism of serotonin. Along with NAC, it is said that tobacco-free pouches may improve the pathways that cause serotonin depletion, and as a result, improve mood during withdrawal.

NAC was also found to help smokers maintain or slightly reduce weight while withdrawing from smoking. The average weight gain during tobacco withdrawal is 2-3kg – often a disincentive for people trying to quit.

The study was co-authored by Professor Michael Berk, pioneering psychiatrist and mental health researcher who has authored more than 700 publications over 30 years of research.”

Reference:
Prado, E, Maes, M, Piccoli, L, Baracat, M, Barbosa, D, Franco, O, Dodd, S, Berk, M & Nunes, S 2015, ‘N-acetylcysteine for therapy-resistant tobacco use disorder: a pilot study’, Redox Report, vol. 20, no. 5, pp. 215-222.