Why Are The Depressed Much More Likely To Smoke Cigarettes?
People diagnosed with some form of mental illness have steeply increased odds of smoking cigarettes. Doctors and researchers have proposed a range of underlying mechanisms to explain this connection between cigarette use and mental health issues. In a study published in April 2014 in the journal European Addiction Research, a team of Dutch researchers investigated how blood levels of a nicotine byproduct called cotinine affect any given person’s risks for having diagnosable problems with depression or an anxiety disorder.
Almost 20 percent of American adults have some form of diagnosable mental health problem. A similar percentage of the total adult population smokes cigarettes. However, current figures indicate that more than a third of U.S. adults with a mental illness diagnosis are smokers.
Additional Groups That Have A Greater Chance Of Smoking
In addition, researchers know that certain segments of the larger population of mentally ill adults have unusually heightened odds of being smokers, including younger individuals, those with relatively little educational achievement, people living in poverty and people with an Alaska Native or American Indian racial/ethnic background.
Explanations for the link between mental illness and smoking that have at least some scientific support include a tendency among people diagnosed with mental health problems to use cigarettes as a form of self-medication, an increased tendency toward mental illness among people who smoke and an increased tendency for smokers to use alcohol or other substances that carry their own separate mental health risks.
Nicotine And Cotinine
Nicotine is the addictive substance responsible for fostering the patterns of repeated cigarette use common among smokers. Any given cigarette contains roughly 1 to 2 mg of nicotine, the federal Centers for Disease Control and Prevention report. This nicotine travels through the bloodstream to the brain, where it produces its mind-altering and addiction-promoting effects. After producing these effects, the drug does not immediately leave the body.
Instead, it lingers in the bloodstream for a number of hours before breaking down into its main byproduct, cotinine. Cotinine stays in the body much longer than nicotine, and is therefore easier to trace. For this reason, in laboratory experiments, researchers commonly use the level of cotinine in a person’s bloodstream to track his or her involvement in cigarette use. While this byproduct always stays in the body longer than nicotine, the rate of cotinine processing varies from person to person.
How Smokers’ Cotinine Levels Affect Mental Illness
In the study published in European Addiction Research, researchers from three Dutch institutions explored the role of cotinine levels in determining which cigarette users have increased chances of developing diagnosable symptoms of major depression or another depressive disorder, or symptoms of any one of the conditions known collectively as anxiety disorders (panic disorder, general anxiety disorder, social phobia, etc.).
The data for this exploration came from 1,026 cigarette-using adults enrolled in a project called the Netherlands Study of Depression and Anxiety. All told, 692 of these cigarette users had active symptoms of a depressive disorder or an anxiety disorder. Another 190 study participants had a previously diagnosed case of depression or anxiety currently in remission, while the remaining 144 participants had no history of diagnosable depression or anxiety.
The researchers calculated the number of cigarettes smoked on a daily basis by each study participant, as well as the amount of cotinine found in the bloodstream after cigarette use occurred. After completing these calculations, they concluded that, for any given amount of cigarettes smoked, those individuals with relatively low levels of cotinine in their bloodstreams have the highest chances of experiencing diagnosable symptoms of anxiety or depression. The difference in cotinine levels is especially stark between those individuals currently affected by depression or anxiety and those individuals who have never had symptoms of these mental health problems.
The authors of the study published in European Addiction Research believe that smokers affected by a depressive disorder or an anxiety disorder may process the cotinine left over in their bloodstreams at a substantially faster pace than smokers not affected by depression or anxiety.
In turn, they believe that this faster cotinine processing may help provide an underlying reason for the relatively high daily cigarette intake among anxious and/or depressed smokers, as well as an underlying reason for the relatively poor smoking cessation outcomes for anxious and/or depressed cigarette users who try to quit.