Previous research has demonstrated that the psychological morbidity experienced by informal caregivers is associated with increased vulnerability to infectious diseases, in particular influenza. A pragmatic trial was conducted to examine whether a stress management intervention (SMI) could reduce psychological morbidity and enhance the antibody response to influenza vaccination in the elderly, and whether changes in immune response of SMI participants were associated with hypothalamic-pituitary-adrenal (HPA) axis activity.
Forty-three elderly spousal carers of dementia patients and 27 non-carer controls were recruited. Sixteen carers were allocated to an 8-week SMI or a non-intervention condition (n = 27). The non-carers formed a no treatment, 'normal' comparison group. At the end of the SMI or its equivalent time period, all participants received an influenza vaccination. IgG antibody titres to the vaccine were measured 0, 2, 4 and 6 weeks post-vaccine.
There was evidence of elevated distress in both carer groups compared with non-carer controls throughout the SMI period, but no between-group differences in salivary cortisol. Immune responses to the vaccine revealed that 50% of SMI carers, 7% of non-intervention carers and 29% of non-carer controls produced a four-fold increase in antibody titre.
The immune response to influenza vaccination appears amenable to improvement through stress management, although the mechanisms underlying this effect remain unclear.