Older depressed adults with a high volume of white matter hyperintensities (WMH) are more at risk for functional decline than both older adults who have not been diagnosed with depression and older adults with low volumes of WMH, according to a study.
At the beginning of this research project 381 individuals aged 60 years and older responded to the Duke Depression Evaluation Schedule’s questions about their functional limitations. This same group, which comprised 244 patients with major depression and 137 individuals who had never been depressed (the controls), also underwent magnetic resonance imaging to identify their total volume of WMH (periventricular and deep white) at baseline. The median length of follow-up for the study’s participants was 5 years, with some individuals having been studied for as many as 16 years.
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“We estimated linear mixed models to measure the associations between white matter lesion volume [seen through brain imaging as hyperintensities] at baseline and change in functional status over time for each participant, controlling for age, sex, race, years of education, [Mini-Mental State Exam] score, and self-reported hypertension at the time of study enrollment,” said Dr. Celia F. Hybels and her colleagues of the department of psychiatry and behavioral sciences, Duke University Medical Center, Durham, N.C.
Those study participants who were both depressed and had a higher volume of WMH at baseline were at greatest risk for functional decline. As for the group of individuals who had never been depressed, the ones with a higher WMH volume at the beginning of the study “had a more accelerated rate of functional decline,” compared with the others in the control group. In contrast to the depressed patients with a higher volume of WMH at baseline, the depressed patients with a lower WMH volume at baseline appeared to experience functional decline at a similar rate as those in the control group with lower WMH volume.
This study found that “depression is a modifier in the association between WMH and functional decline in older adults, which suggests one pathway by which older depressed adults develop disability. Those older adults with increased WMH volume who were also depressed had a sharper increase in the number of limitations over time, compared with older adults with a lower volume of WMH who were also depressed and with older adults without a history of depression. That depression is a moderator in the association between white matter pathology and functional decline suggests a unique contribution of depression,” the researchers said.
The researchers suggested that follow-up studies use physical performance to measure the functional status of individuals instead of self-report.
Read the study in The American Journal of Geriatric Psychiatry (doi: 10.1016/j.jagp.2015.03.001).