Caregiver Burden and Distress As Mediators in the Relationship between Behavioral and Psychological Symptoms in Persons with Alzheimer's Disease and Depression in Caregiver

Background/Purpose

Alzheimer’s disease (AD) is the most common neurodegenerative disease, and is a leading cause of dementia. Behavioral and psychological symptoms (BPS), also known as neuropsychiatric symptoms, represent a heterogeneous group of non-cognitive symptoms and behaviors occurring in persons with AD (PwAD). Behavioral changes in PwAD are often associated with negative outcomes for informal caregivers of PwAD such as depressive symptoms. Psychosocial factors also predict caregiver depression such as higher perceived level of burden and higher level of distress related to BPS. Guided by Pearlin’s Stress Process Model, the current study examines whether the relationship between BPS in PwAD and caregiver depression is mediated by caregiver burden and BPS-related distress.

Methods

Data were collected from the South Carolina AD Registry. The study sample was recruited in 2010, with 705 dyads of PwAD and informal caregivers completing the interview. PwAD in the sample were all enrolled in a Medicaid waiver program. Measures used in the study included CESD-R-10 (depression), NPI (BPS, caregiver distress), and 4-item screening version of Zarit Burden Interview (caregiver burden). Mediation effect was determined by procedures described by Baron and Kenny (1986). Sobel’s (1982) test of significance was performed to determine the extent to which a mediator contributed to the total effect on the dependent variable.

Results

The total effect of BPS on caregiver depression was significant on average (b = .11, p< .0001). NPI was significantly predictive of the hypothesized mediating variable, caregiver burden (b = .08, p< .0001). When regressing caregiver depression simultaneously on the BPS and caregiver burden, the result indicated that there were significant relationships between BPS and caregiver depression (b =.06, p< .0001), and between caregiver burden and caregiver depression (b =.78, p< .0001). Caregiver depression was predicted well by BPS and caregiver burden, with R² = .39 (p< .0001). By using the Sobel’s test, the indirect effect was 9.53 (p< .0001). While the direct path from BPS to caregiver depression was statistically significant, the effects of NPI on caregiver depression were partially mediated by caregiver burden.

Using the same steps, BPS was a significant predictor of caregiver distress (b = .41, p< .0001). When regressing caregiver depression simultaneously on the BPS and caregiver distress, the result indicated that the previously significant relationship between BPS and caregiver depression becomes non-significant (b = .00, p= .917). Caregiver distress was significantly associated with caregiver depression (b = .29, p< .0001). Caregiver depression was predicted well by BPS and caregiver distress, with R² = .27 (p< .0001). By using the Sobel’s test, the indirect effect was 7.58 (p< .0001). Therefore, there is almost complete mediation effect for caregiver distress in the relationship between NPI and caregiver depression.

Conclusions and Implications

The results indicated that severity of BPS in PwAD is associated with caregiver depression partially through BPS-related distress and caregiver burden. In order to reduce caregiver’s depression, intervention programs are recommended to increase focus on educating caregivers about handling behavioral changes in PwAD as well as reducing caregiver’s perceived level of burden related to caregiving.