Depression in caregivers of demented patients is associated with altered immunity: impaired proliferative capacity, increased CD8+, and a decline in lymphocytes with surface signal transduction molecules (CD38+) and a cytotoxicity marker (CD56+ CD8+)

Abstract

SUMMARY Changes in relevant immune parameters, including function, were found to be associated with depression in elderly caregiver wives of demented patients. We studied the relationship between immune cell phenotype and T cell proliferative capacity of such caregivers to levels of stress and depression over the course of a support group intervention. The data indicate the strongest association between depression (of all stress parameters) and impaired T cell proliferative capacity. Depression was also most strongly (of stress parameters) associated with a shift in T cell populations with an increase in CD8+ T cells, and a reduced percentage of CD38+ cells in both CD8+ and CD4+ T cell populations. Since CD38 is a signal transduction factor, it was interesting that a decreased percentage of CD38+ cells correlated with impaired T cell function (proliferation). Another significant difference was the reduction in natural killer (NK) cells as well as the percentage of the CD56+ component of the CD8+ population. This latter subset is important in MHC-unrestricted cytotoxicity, and has been found expanded in healthy centenarians. This study shows that both chronic stress, and depression in particular, and age have deleterious effects on T cells, and together could significantly contribute to the higher risk of disease and mortality associated with being a caregiver of a demented individual.