- 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
- "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
- "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
- 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
- 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."