Funded by the National Institute on Aging (NIH)
(Michele C. McDonnall, Ph.D, P.I.) firstname.lastname@example.org
A much larger proportion of older persons with dual sensory loss experience syndromal or subsyndromal depression compared to the general population. As depression is associated with reduced quality of life and the incidence of dual sensory loss is rising with the increasing life span in the United States, this presents an important public health concern in this country. The population of older persons who acquire dual sensory loss later in life has, to date, received little attention by researchers. For example, currently nothing is known about the longitudinal effects of acquiring dual sensory loss on depression. Also, we do not know why many older people with dual sensory loss experience depression or its symptoms, while many others do not experience negative effects in this area.
Determining the reason for these differences is important. Of particular importance is detecting reasons that are adaptable (i.e., ones that can be changed by the individual), as these factors may give individuals some ability to control their own outcomes. If factors are identified that can reduce the negative effect of dual sensory loss on depression, interventions could be developed to directly assess the ability of changes in these areas to decrease the psychological dysfunction associated with dual sensory loss. A first step in this direction is identifying adaptable factors that can reduce the negative effect of dual sensory loss on depression.
Given the lack of research with this population in this area, I will first investigate how acquiring a dual sensory loss affects symptoms of depression over time. After determining this, the ability of adaptable factors to moderate the relationship will be investigated. Therefore, the primary goals of this project are to:
- Determine the effects over time of acquiring a dual sensory loss on subsyndromal depression.
- Determine whether identified adaptable factors can moderate the negative effect of dual sensory loss on subsyndromal depression.
The factors that were tested as to their ability to moderate the relationship between subsyndromal depression (or depressive symptoms) and DSL were physical status and participation in productive activities, each of which will be measured with three variables. Health and Retirement Study (HRS) and Aging and Health Dynamics study (AHEAD) data (from years 1993, 1994, 1995, 1996, 1998, 2000, 2002, and 2004) was used to conduct the research. The sample included persons who self-reported development of a DSL during the course of data collection and a comparison group of persons without sensory loss matched on age (N=3,024). Hierarchical linear modeling was used to analyze the data. Individual growth curve models determined (a) the average rate of change in depressive symptoms, (b) the individual variability in change in depressive symptoms over time, and (c) the effects of physical status and participation in productive activities on trajectories of depressive symptoms for this population.
The following significant findings were obtained from this research:
- Development of a DSL was associated with an increase in depressive symptoms, both initially (at the first time reporting DSL) and over time. The increase over time was curvilinear, which was considered indicative of an adjustment process taking place. Having a pre-existing vision loss or hearing loss did not alter these effects, but a pre-existing vision loss was associated with higher initial depressive symptoms scores. The effect of DSL on depressive symptoms did not differ based on gender, race/ethnicity, or age.
- Although experiencing a DSL caused an increase in depressive symptoms initially and over time as expected, a large difference in depression scores between those who develop DSL and those without sensory loss occurred prior to the development of the DSL. This difference existed between the groups at the outset of the study, many years prior to the time the majority of participants developed DSL. This suggests that there may be significant pre-existing differences between the groups in other areas.
- Participation in three productive activities (employment, volunteer work, and informal helping) were each associated with a reduction in the experience of depressive symptoms for adults with DSL. However, the only productive activity that provided an extra benefit to persons with DSL (compared to the general population) was participating in volunteer work. The size of this effect was more than three times larger for persons with DSL than the general population.
- Three measures of physical status (vigorous physical activity, physical condition, and body mass index [BMI]) were found to moderate the effect of DSL on depressive symptoms. Each variable exhibited a larger effect for persons with DSL (compared to the comparison group); two of the variables also had a larger effect for these persons prior to the development of the DSL. Participation in vigorous physical activity resulted in a slight decrease in depressive symptoms among persons in the DSL group, both before and after they developed the DSL. Physical condition level predicted depressive symptoms for both the DSL group and the general population, but the effect was more than twice as large for the DSL group (again, both before and after they developed the DSL). BMI did not have the effect expected: instead of higher BMI being associated with greater levels of depressive symptoms, it was associated with lower levels of depressive symptoms for persons with a DSL, although the effect size was small. Post-hoc analyses utilizing weight categories (i.e., underweight, overweight, and obese) instead of continuous BMI were conducted; only the interaction between DSL and being underweight was a significant positive predictor of depressive symptoms, indicating that this is primarily where the effect of BMI on depressive symptoms originated.
The following publications were developed based on this research:
- McDonnall, M. C. (2009). The effects of developing a dual sensory loss on depression in older adults: A longitudinal study. Journal of Aging and Health, 21(8), 1179-1199.
- McDonnall, M. C. (2011). Physical status as a moderator of depressive symptoms among older adults with dual sensory loss. Rehabilitation Psychology, 56(1), 67-76.
- McDonnall, M. C. (2011). The effect of productive activities on depressive symptoms among older adults with dual sensory loss. Research on Aging, 33(3), 234-255.