Gratitude has been described as an adaptive evolutionary mechanism that is relevant to healthy psychological and interpersonal outcomes. Questions remain as to whether the presence and benefits of gratitude are consistent from young adulthood to old age; prior research has yielded mixed evidence. We examined the magnitude and direction of age differences in gratitude in three samples (combined N = 31,206). We also examined whether gratitude was associated with greater/lesser well-being at different periods in the life course. We found that the experience of gratitude was greatest in older adults and least in middle aged and younger adults. Further, we found that the associations between gratitude and subjective well-being remained relatively constant across the lifespan. Findings are discussed from a developmental perspective.

Findings support the dyadic biopsychosocial model of marriage and health indicating: (a) stress and relationship quality directly effect the cardiovascular system, (b) relationship quality moderates the effect of stress, and (c) the dyad rather than only the individual should be considered when examining marriage and health.

Findings highlight the complexity of relationship quality. Individuals appeared to benefit from aspects of both high- and low-quality spouse/partner relations but only under high levels of stress. Findings are inconsistent with traditional moderation hypotheses, which suggest that better quality ties buffer the stress-health link and lower quality ties exacerbate the stress-health link. Results offer preliminary evidence concerning how spousal ties "get under the skin" to influence physical health.

Results are discussed in light of the value of including personality in, and its contribution to, studies of activity engagement in later life. In addition, the need to acknowledge the complexity of the concept of activity engagement in future research is highlighted.