Info

Figure 4. NK activity across the four cf fee tor- to- target cell ratios in controls subjects (x), primary alcoholics (closed circles), primary alcoholics with secondary depression {open circles), depressed patients (closed triangles). and depressed patients with histories of alcohol abuse (open triangles).

40:1 20:1 10:1 5:1 EffectonTarget Cell Ratio

Figure 4. NK activity across the four cf fee tor- to- target cell ratios in controls subjects (x), primary alcoholics (closed circles), primary alcoholics with secondary depression {open circles), depressed patients (closed triangles). and depressed patients with histories of alcohol abuse (open triangles).

3.3.3. Tobacco dependence. In view of the prevalence of tobacco dependence in depressed subjects (Breslau et al., 1998) and the possible influence or cigarette smoking on immune function (Ferson, Edwards, Lind, Milton, & Hersey, 1979), it is also important to examine whether cigarette smoking moderates the relationship between depression and immunity. However, only a few studies concerned with immune alterations in depressed subjects have assessed smoking histories (Irwin et al., 1990b; Andreoli, Keller, Rabaeus, Marin, Bartlett, & Taban, 1993). While neither study found that smoking histories correlated with immune function in depressed subjects, the lack of a relationship between quantity of cigarette use and NK activity is not surprising due to a rather restricted range of cigarette use in the depressed subjects with most reporting moderate (1-2 packs per day) consumption. To our knowledge, no study has evaluated whether there is a possible interaction between depression and smoking on enumerative- and functional measures of immunity.

We recently examined the influence of current cigarette smoking on total white blood cells, numbers of major immune cell classes, and NK activity in depressed subjects and in controls (Jung & Irwin, 1998). In a large series of previously described subjects (n = 245), depressed subjects, and controls were stratified on the basis of nonsmoking and current smoking status. Values of total white blood cell counts and differentia! and of NK activity were compared in the four groups.

For total white blood cell count, depressed subjects showed on the average higher numbers of total cells than controls, and smokers had elevated total white blood cell counts as compared to nonsmokers. In addition, there was a significant interaction between depression and smoking on total cell counts. Depressed smokers had higher numbers of white blood cells than depressed nonsmokers and control nonsmokers and smokers. No effect for smoking or interaction between depression and smoking was found for percentages of neutrophils, lymphocytes, or monocytes.

For NK activity, there was a significant effect for depression. Depressed subjects showed on the average lower values of NK activity than controls. However, pairwise comparisons demonstrated that the difference between depressed subjects and controls was due to the marked reduction of NK activity in the depressed smokers as compared to the depressed nonsmokers.

It did not appear that the immunologic changes found in depressed smokers were due to the simple effects of smoking. Controls who were current smokers showed white blood cell counts and levels of NK activity that were similar to those found in control nonsmokers. Furthermore, there was no correlation between amount of smoking and NK activity in either the control- or depressed smokers, a finding consistent with previous studies of smoking populations (Meliska, Stunkard, Gilbert, Jensen, & Martinko, 1995).

These data have several implications. First, smoking status is a critical variable to assess in studies examining the relationship between depression and immunity. The combined effects of depression and smoking appear to predict changes in numbers of white blood cells and NK activity independent of the effects of depression and smoking alone. Due to the interaction between depression and smoking on total white blood cell counts and NK activity, inconsistent findings are likely to be reported if different studies have samples of depressed subjects who differ in the prevalence of smoking. Cigarette use alone and/or in combination with depression might also contribute to the suppression of other nonspecific measures of immune function such as mitogen-induced lymphocyte proliferation. Moreover, cigarette smoking is associated with immune activation (Mendall, Patel, Asante, Ballam, Morris, Strachan, Camm, & Northfield, 1997) and it is important to address whether smoking status alters the reported the relationship between depression and increases in serum levels of inter-leukin-6 and acute phase proteins.

The health implications of reduced NK activity in depressed smokers are uncertain. However, there is evidence that depression might interact with other characteristics such as cigarette smoking to impact health, rather than there being a unitary link between depression and cancer. In a 12-year follow-up of 2264 adult men and women, depressed mood was found to interact with cigarette smoking, and together depressed mood and cigarette smoking were associated with a marked increase in the relative risk of cancer (Linkins & Comstock, 1990). As compared to the risk seen in never smokers who were without depressed mood, smokers with depressed mood as measured by elevated scores on the Clinical Epidemiological Scale for Depression had a relative risk of 18.6 for cancers at sites associated with smoking and a relative risk of 2.9 for cancers at sites not associated with smoking. In contrast, smokers who were without depressed mood showed only a relative risk of 4.2 for cancers at sites associated with smoking and no increase in relative risk of cancers at sites not associated with smoking.

Anxiety and Depression 101

Anxiety and Depression 101

Everything you ever wanted to know about. We have been discussing depression and anxiety and how different information that is out on the market only seems to target one particular cure for these two common conditions that seem to walk hand in hand.

Get My Free Ebook


Post a comment