Quit Smoking, Quit Depression

June 17, 2014

Researchers have made bold claims about cigarette smoking leading to depression.

It has long been known that smokers have higher rates of depression than nonsmokers, but researchers from the University of Otago in New Zealand investigated the link further, and say they have found a causal relationship.

The team took figures from over 1,000 men and women aged 18, 21 and 25 years. Smokers had more than twice the rate of depression.

Using a computer modeling approach, their analysis supported a pathway in which nicotine addiction leads to increased risk of depression.

“The best-fitting causal model was one in which nicotine dependence led to increased risk of depression,” the researchers said. They suggest two possible routes, one involving common risk factors, and the second a direct causal link.

According to the researchers, this evidence is consistent with the conclusion that there is a cause and effect relationship between smoking and depression in which cigarette smoking increases the risk of symptoms of depression.

The researchers say that relief from negative mood due to smoking depends on the situation rather than nicotine intake. These results challenge the common assumption that smoking, and nicotine in particular, broadly alleviates negative effect.

One major factor must be the smoker’s expectations. These were investigated by a team at the University of Montana. They write, “Expectancies about nicotine’s ability to alleviate negative mood states may play a role in the relationship between smoking and depression.”

They asked 315 undergraduate smokers to complete a survey, which supported the theory. Smokers believed that “higher levels of tobacco smoking will reduce negative emotions.” This expectation fully explained the link relationship between depressive symptoms and smoking.

Despite what you may think, cigarettes don’t boost your mood. Two questionnaires filled out three years apart by 4,800 daily smokers showed that smokers who’d quit since the first survey were a lot happier by the second.

Could the link between tobacco smoking and depression actually be due to other substance dependencies? Stopping smoking is associated with long-term improvements in mental health, debunking the myth that smoking is stress relieving.

So it seems that the evidence is stacked against nicotine as a mood lifter, despite widely-held beliefs to the contrary.