Table 1.
Serum Biomarkers of Immune System and Inflammation Extracted From Blood Samples in 30 Studies
| Study | Caregivers | Controls | Biomarkers | Category | Potential bias |
|---|---|---|---|---|---|
| 1. Kiecolt-Glaser et al. (1987) | 34 dementia | 34 demographically matched | % helper T lymphocytes | Immune | Moderate |
| % NK cells | Immune | ||||
| % suppressor T | Immune | ||||
| % total T lymphocytes | Immune | ||||
| EBV VAC | Immune | ||||
| Helper/suppressor ratio | Immune | ||||
| 2. Reese et al. (1994) | 50; 25 dementia, 25 stroke | 25 noncaregivers | % CD3 | Immune | Moderate |
| % CD4 | Immune | ||||
| % CD8 | Immune | ||||
| % leukocytes | Immune | ||||
| % NK cells | Immune | ||||
| 3. Irwin et al. (1997) | 100 dementia, spouses only | 33 volunteers | NK activity | Immune | Low |
| 4. Mills et al. (1997) | 27 dementia, spouses only | 10 matched volunteers | CD16 count | Immune | Moderate |
| CD4 count | Immune | ||||
| CD8 count | Immune | ||||
| 5. Cacioppo et al. (1998) | 27 dementia, spouses only, women only | 37 controls | Cell Prolif to Con A | Immune | Moderate |
| Cell Prolif to PHA | Immune | ||||
| NK cell cytotoxicity | Immune | ||||
| 6. Scanlan, Vitaliano, Ochs, Savage, and Borson (1998) | 81 dementia, spouses only | 82 age- and gender-matched spouses of persons without dementia | %CD4 | Immune | Low |
| %CD8 | Immune | ||||
| 7. Vitaliano et al. (1998) | 80 dementia, spouses only | 85 age- and gender-matched spouses of persons without dementia | NK activity | Immune | Low |
| 8. Lutgendorf et al. (1999) | 18 dementia, women only | 15 noncaregiving (and nonmoving) women | IL-6 | Inflammation | Moderate |
| 9. Bauer et al. (2000) | 49 dementia, spouses only | 67 “closely matched” controls | Cell Prolif to PHA | Immune | Low |
| IL-2 | Inflammation | ||||
| 10. Stowell, Kiecolt-Glaser, and Glaser (2001) | 61 dementia | 78 “comparison” participants | % CD3 | Immune | Moderate |
| % helper T cells | Immune | ||||
| % T (suppressor/cytotoxic) | Immune | ||||
| Log Con A | Immune | ||||
| Log PHA | Immune | ||||
| Helper/suppressor ratio | Immune | ||||
| 11. Vedhara et al. (2002) | 41 multiple sclerosis, spouses only | 62 noncaregiving controls | IFN-γ | Inflammation | Low |
| IL-4 | Inflammation | ||||
| 12. Provinciali et al. (2004) | 38 caregivers of home health care patients, nonspouses only | 37 age- and sex-matched controls | % CD16 | Immune | Minimal |
| % CD56 | Immune | ||||
| NK activity | Immune | ||||
| 13. Vitaliano, Persson, Kiyak, Saini, and Echeverria (2005) | 123 dementia, spouses only | 117 noncaregiving spouses | CRP | Inflammation | Low |
| WBC | Inflammation | ||||
| 14. Graham et al. (2006) | 113 dementia, spouses only | 101 controls | CRP | Inflammation | Moderate |
| IL-6 | Inflammation | ||||
| 15. von Kanel et al. (2006) | 116 dementia, spouses only | 54 noncaregivers | CRP | Inflammation | Low |
| D-dimer | Inflammation | ||||
| IL-6 | Inflammation | ||||
| 16. Aschbacher et al. (2007) | 51 dementia, spouses only, women only | 27 noncaregiving women | % Aggregates | Inflammation | Low |
| 17. Damjanovic et al. (2007) | 38 dementia | 38 age- and gender-matched controls | B cell (CD19) count | Immune | Low |
| CD4 count | Immune | ||||
| CD8 count | Immune | ||||
| GM-CSF | Inflammation | ||||
| IFN-γ | Inflammation | ||||
| IL-2 | Inflammation | ||||
| IL-4 | Inflammation | ||||
| IL-6 | Inflammation | ||||
| IL-8 | Inflammation | ||||
| Monocyte (CD14) | Immune | ||||
| NK cell | Immune | ||||
| 18. Miller et al. (2008) | 11 glioblastoma (brain tumor) caregivers | 10 matched controls | IL-1 | Inflammation | Moderate |
| 19. Segerstrom, Schipper, and Greenberg (2008) | 14 dementia | 30 controls | IL-6 | Inflammation | Low |
| 20. Rohleder, Marin, Ma, and Miller (2009) | 18 glioblastoma (brain tumor) caregivers | 19 matched controls | CRP | Inflammation | Moderate |
| IL-6 | Inflammation | ||||
| 21. Fonareva, Amen, Zajdel, Ellingson, and Oken (2011) | 20 dementia | 20 noncaregivers free of “any major stress” | CRP | Inflammation | Low |
| IL-6 | Inflammation | ||||
| TNF-α | Inflammation | ||||
| 22. Kiecolt-Glaser et al. (2011) | 58 dementia | 74 noncaregivers | IL-6 | Inflammation | Moderate |
| TNF-α | Inflammation | ||||
| 23. Gouin, Glaser, Malarkey, Beversdorf, and Kiecolt-Glaser (2012) | 53 dementia | 77 noncaregivers | CRP | Inflammation | Minimal |
| 24. von Kanel, Mausbach, et al. (2012) | 93 dementia, spouses only | 43 married controls | Endothelin-1 | Inflammation | Low |
| IC adhesion | Inflammation | ||||
| IL-8 | Inflammation | ||||
| IFN-γ | Inflammation | ||||
| Plasminogen activator inhibitor | Inflammation | ||||
| Serum amyloid A | Inflammation | ||||
| TNF-α | Inflammation | ||||
| VC adhesion | Inflammation | ||||
| 25. von Kanel, Mills, et al. (2012) | 118 dementia, spouses only | 51 controls | IL-10 | Inflammation | Low |
| IL-12 | Inflammation | ||||
| 26. Wong et al. (2013) | 55 caregivers of multiple conditions, spouses only | 61 age- and sex-matched noncaregivers | % B lymphocyte | Immune | Minimal |
| % cyto T | Immune | ||||
| % NK | Immune | ||||
| % T helper | Immune | ||||
| % T suppressor | Immune | ||||
| % total T cell | Immune | ||||
| 27. Kang and Marks (2014) | 49 adult child caregivers | 914 noncaregivers | Inflammatory composite | Inflammation | Minimal |
| 28. Kim and Ferraro (2014) | 313 caregivers of “day-to-day activities” | 1477 noncaregivers | CRP | Inflammation | Minimal |
| 29. Miller et al. (2014) | 33 glioblastoma (brain tumor) caregivers | 47 controls “without major stressors … during the previous year” | CRP | Inflammation | Moderate |
| NF-κB | Inflammation | ||||
| 30. Bevans et al. (2016) | 20 stem cell transplant caregivers | 20 noncaregivers | IL-6 | Inflammation | Low |
| TNF-α | Inflammation |
Notes: CRP = C-reactive protein; IFN = interferon; IL = interleukin; NF-κB = nuclear factor kappa B; NK = natural killer; TNF = tumor necrosis factor; WBC = white blood cell; EBV VAC = Epstein-Barr virus capsid antigen; GM-CSF = Granulocyte-macrophage colony-stimulating factor; PHA = phytohemaglutinin; VC = Vascular Cellular.