Smoking Linked to Depression and Anxiety in MS: Review Study

Quitting smoking appears to ease anxiety, but not depression

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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An illustration of smoking cigarettes.

Smoking tobacco products is associated with a higher prevalence of depression and anxiety among multiple sclerosis (MS) patients, according to a recent systematic review.

Across the evaluated studies, current smoking was linked to a 1.3–2.3 times higher prevalence of depression, and about a 1.2 times higher rate of anxiety.

Quitting smoking appeared to ease anxiety levels, whereas depression tended to persist despite smoking cessation.

Still, differences between the studies, including how smoking, anxiety, and depression were measured, make the findings more difficult to interpret.

“Future prospective studies with uniform measurements of smoking and validated tools and consistent cut-offs for depression and anxiety to confirm suggested relationships between current-smoking and former-smoking and depression and anxiety are advised,” researchers wrote.

The study, “The association between tobacco smoking and depression and anxiety in people with multiple sclerosis: A systematic review,” was published in Multiple Sclerosis and Related Disorders.

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Smoking linked to greater likelihood of developing MS, disability progression

A well-established link exists between smoking and MS, with current smoking being linked with a greater likelihood of developing the disease and to greater disability progression in people with MS. Smoking is also associated with a higher risk of a relapsing-remitting disease course converting to secondary progressive MS, and quitting smoking has been linked to slower MS progression.

Anxiety and depression are highly prevalent symptoms in the MS population, although “under-recognized and under-treated,” according to the researchers. Limited evidence suggests that tobacco use may be linked to the presence of anxiety and depression in MS, but the relationship remains unclear.

To clarify the potential link, a team of researchers in Australia conducted a systematic review of published studies that assessed smoking, depression, and anxiety in MS. The goal was to determine among MS patients whether current or former smokers were at an increased risk of anxiety and depression compared with non-smokers.

A total of 13 publications, covering 12 individual studies, were included in the review.

Of them, eight were cross-sectional, meaning the relationship was evaluated at a single point in time, while three were prospective, in which individuals were followed over time. One study was retrospective, where participants reported about their past, and one comprised both retrospective and prospective components.

All of the studies used a quantitative self-report tool to assess depression and/or anxiety that was validated for the MS population. Questionnaires included the Hospital Anxiety and Depression Scale, the 9-item Patient Health Questionnaire (PHQ), the 2-item PHQ, the Beck Depression Inventory, and the State-Trait Anxiety Inventory.

Of 12 studies that examined a relationship between current smoking and depression, nine identified a positive association between them.

One study found 2.3 higher prevalence of depression in smokers

For example, one large, international cross-sectional study found the prevalence of depression to be 2.3 times higher in current smokers compared with non-smokers. In another prospective study from the U.K., depression increased at a significantly faster rate over a four-year period in MS patients who currently smoked compared with those who never smoked.

Across all the studies that identified a relationship, the rates of depression were found to be 1.3–2.3 times higher in current smokers than in non-smokers.

The relationship between smoking and depression could be related to the immunomodulatory and inflammatory effects of consuming tobacco, the researchers suggested, noting that smoking might negate the immune-modulating effects of some disease-modifying therapies.

Regarding anxiety, four out of five studies — one cross-sectional study and three prospective studies — found a relationship between the condition and smoking among MS patients.

In general, smoking was associated with about a 20% higher risk of anxiety.

This review contributes to a growing body of literature linking smoking with adverse health outcomes in [people with MS].

Smoking cessation appears to have different effects on anxiety and depression

Interestingly, stopping smoking appeared to have different effects on anxiety and depression. While one study found that stopping smoking did not significantly improve depression, another study showed it helped to decrease anxiety.

“Collectively, these studies suggest biopsychosocial mechanisms underlying the smoking-depression and smoking-anxiety relationships may be different,” the researchers wrote.

Overall, “this review contributes to a growing body of literature linking smoking with adverse health outcomes in [people with MS],” the team wrote.

It also provides support for efforts to increase awareness about the risks of smoking.

“Future interventional research is required to determine the efficacy of psychological therapies for smoking cessation,” the researchers wrote.

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