Smoking And Depression
Subdue Immune System
By Twinkle Chisholm
If you have found yourself sitting along for hours on end, puffing on cigarettes and dwelling on why your life isn't where you think it should be you may understand the relationship between cigarettes and depression.
But more importantly, a new study has found that the combination of smoking and depression may weaken the immune system.
"It is the synergistic interaction between depression and smoking that seems to be important," says Michael Irwin, MD. He, along with Dr. Waymund Jung, conducted the research at the University of California, San Diego and the Veterans Affairs San Diego Healthcare System Administration Medical Center. The results of their research appear in the June issue of Psychosomatic Medicine.
The combination of depression and cigarette smoking contributes to an increased white blood cell count and the decline in the activity of natural killer (NK) cells. The NK cells are part of the immune system's first line of defense that helps to fight off tumors.
"In addition," says Irwin, "we know that depressed people tend to have high levels of stress hormones. These hormones have suppressive effects on some parts of the immune system and actually enhance other parts of the immune system. That's why some depressed patients get infectious diseases and others suffer from auto-immune disturbances which are caused by increased immune activity."
Two hundred and fifty four men participated in the study: 61 depressed moderate smokers, 46 depressed non-smokers, 127 non-depressed non-smokers and 11 non-depressed moderate smokers.
Researchers found that the depressed smokers had lower NK activity than did the depressed non-smokers. Those who were not depressed had similar levels of NK activity whether or not they smoked.
"We know that depressed patients smoke at an increased rate compared to the population at large," says Irwin. "In California for an example, many smokers, even those who only smoke about a pack a day, have a lifetime history of some psychiatric disorder."
Another way researchers tested the difference in the effect of nicotine on depressed and non-depressed people was to look at sleep alterations, such as their rapid eye movement. Rapid eye movements increased in the depressed people when they were given nicotine.
"The reaction was the opposite in the non-depressed patients, their rapid eye movement actually decreased when they were given nicotine," Irwin explained. "This was even true of people who were non-smokers."
Those who were depressed and showed the greatest sleep alterations tended to be those who are most likely to show the greatest change in immune system function.
"Depression itself may not be all that important when it comes to the immune system," says Irwin. "It seems that it is the combination of smoking and depression that is really critical.
Irwin sites the relative risk of cancer to those who are both depressed and smoke. "We know that smokers are at greater risk for some sorts of cancer, such as lunch, than the rest of the population. However, being depressed and smoking seems to increase the risk for cancers that are not typically linked to smoking, for example GI (gastrointestinal) cancer."
"It is not depression alone or smoking alone, it is the combination that is really important," says Irwin. "And the problem is compounded by the fact that it seems to be more difficult for depressed people to quit smoking that it is for those who are not depressed."