To estimate the glomerular filtration rate (GFR) in relation to the chronic stress of dementia caregiving and major transitions in the caregiving situation.
We longitudinally assessed 119 people serving as caregivers for their spouses with Alzheimer’s disease and 58 noncaregiving controls for a period of up to 3 years (mean of 2.8 assessments per participant). At baseline, the mean (standard deviation [SD]) age of all participants was 74.5 (7.5) years. Random regression models with fixed and time-variant effects for psychosocial factors, risk factors of chronic kidney disease, and caregiving transitions were used to evaluate changes over time in estimated GFR.
The change in GFR did not differ between caregivers and controls during follow-up (p = .77). Further analyses revealed that GFR declined disproportionately after placement of the spouse in a nursing home at 3 months after placement (−4.9 [2.2] mL/min per 1.73 m2; p = .03). Post hoc analyses showed that this effect was stronger in caregivers with hypertension compared with those without hypertension (−5.7 [3.1] versus −2.4 [3.4] mL/min per 1.73 m2), as well as in caregivers with diastolic blood pressure (BP) levels at 1 SD above the mean than in those with diastolic BP levels at 1 SD below the mean (−8.3 [2.9] versus −1.4 [2.7] mL/min per 1.73 m2).
Kidney function did not differ between caregivers and controls over time. However, GFR had impaired at 3 months after a major caregiving transition. Because the effect of placement of the spouse with Alzheimer’s disease on the decline in GFR was moderated by BP, it might be confined to caregivers who experience increased sympathetic activation after placement.
From the Division of Psychosomatic Medicine (R.v.K.), Department of General Internal Medicine, Inselspital, Bern University Hospital; and University of Bern (R.v.K.), Bern, Switzerland; and Departments of Psychiatry (B.T.M., J.E.D., P.J.M., T.L.P., S.A.-I., I.G.), Medicine (M.G.Z.), and Family and Preventive Medicine (M.A.), University of California, San Diego, La Jolla; San Diego Joint Doctoral Program in Clinical Psychology (S.K.R., E.A.C.), San Diego State University/University of California, San Diego, California.
Address correspondence and reprint requests to Roland von Känel, MD, Division of Psychosomatic Medicine, Department of General Internal Medicine, Inselspital, Bern University Hospital, CH-3010 Bern, Switzerland. E-mail: email@example.com
The study was supported by the National Institutes of Health/National Institute on Aging through award AG 15301 to Dr. Grant. Additional support was provided through award AG 03090 to Dr. Mausbach and AG 08415 to Dr. Ancoli-Israel.
Received for publication April 27, 2011; revision received September 16, 2011.