The role of sustained positive mental health in aging successfully is also of great interest, as it is a potentially modifiable factor. There appears to be an association between age and depressive symptoms. Older adults often experience clinically significant depressive symptomatology, even though they may not meet criteria for major depressive disorder. Often, these nonmajor forms of depression are classified as “subthreshold depression” or “subsyndromal depression.” The prevalence of subthreshold depression ranges from 8.8% to 21.3% (Vahia et al., 2010). Subthreshold depression is associated with numerous negative outcomes. These include increased healthcare utilization, risk of future major depressive disorder, suicide, disability, as well as declines and overall functioning and health-related quality of life (Vahia et al. 2010). In cohorts of older adults, higher prevalence of depressive symptoms also appears to be associated with increased incidence of cognitive impairment (i.e., both mild cognitive impairment and dementia).
Vahia, I. V., Meeks, T. W., Thompson, W. K., Depp, C. A., Zisook, S., Allison, M., ... & Jeste, D. V. (2010). Subthreshold depression and successful aging in older women. The American Journal of Geriatric Psychiatry, 18(3), 212-220.