Immune-inflammatory markers in patients with seasonal affective disorder: effects of light therapy.
BACKGROUND
There is increasing evidence that an activation of the immune-inflammatory system is involved in the pathophysiology of depressive disorders. The purposes of this study were to (1) compare immune-inflammatory markers in patients with seasonal affective disorder (SAD) with those in matched normal controls; and (2) examine the effects of light therapy on the immune-inflammatory markers in patients with SAD.


METHODS
Plasma concentrations of interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R) and soluble IL-2 receptor (sIL-2R) were measured in 15 patients with SAD and 15 age- and sex-matched normal controls. Of the 15 patients, 14 had repeated blood sampling for these variables following 2 weeks of light therapy.


RESULTS
We found that patients with SAD had significantly increased IL-6 levels compared to normal controls (P<0.0005). There was a trend toward increased sIL-2R in patients with SAD (P=0.09). There was no significant difference in sIL-6R level between the two diagnostic groups (P=0.18), but the product term (IL-6xsIL-6R) was significantly higher in patients with SAD than that in normal control controls (P<0.0003). Furthermore, all 14 patients who completed the study improved with 2 weeks of light therapy and nine of them (64%) had 50% reduction in score of the Hamilton Depression Rating Scale-SAD version post-treatment compared to baseline. However, the initially increased immune markers in SAD patients were not significantly altered by the therapeutic light therapy.


CONCLUSIONS
This study was limited to a small sample size and other immune inflammatory markers should be measured for further evidence of immune activation in seasonal depression.


CONCLUSIONS
Our results of increased IL-6, IL-6xsIL-6R, and sIL-2R in patients with SAD suggest an activation of the immune-inflammatory system in winter depression, which is not altered by 2 weeks of successful light therapy.
Graduate Institute of Cell and Molecule Biology, Taipei Medical College, Taipei, Taiwan, ROC.
S J
SJ
Leu
I S
IS
Shiah
L N
LN
Yatham
Y M
YM
Cheu
R W
RW
Lam
D000328:Adult; D015415:Biomarkers / Q000032:analysis; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007249:Inflammation; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D010789:Phototherapy; D015375:Receptors, Interleukin-2 / Q000097:blood*; D019947:Receptors, Interleukin-6 / Q000097:blood*; D016574:Seasonal Affective Disorder / Q000276:immunology* / Q000628:therapy*
D015415:Biomarkers; D015850:Interleukin-6; D015375:Receptors, Interleukin-2; D019947:Receptors, Interleukin-6