Speed of Processing and Depression Affect Function in Older Adults with Mild Cognitive Impairment

Objectives To evaluate the effect of depression and cognition on function in older adults with amnestic and nonamnestic mild cognitive impairment (aMCI and nonaMCI) . Design The study uses baseline data from the National Alzheimer's Coordinating Center . Setting Data were collected at multiple Alzheimer's Disease Centers in the United States . Participants The sample included a total of 3,117 individuals with MCI, mean age = 74.37 years, SD: 9.37 (aMCI, n = 2,488; non-aMCI, n = 629) . Measurements The 10-item Pfeffer Functional Activities Questionnaire assessed function . Results Depressive symptoms (Geriatric Depression Scale), memory impairment (Logical Memory II), and processing speed decrements (Digit Symbol Substitution Test) were significantly associated with functional impairment (p  . Conclusions The findings show that processing speed is central to the effect that depression and executive dysfunction have on functional impairment in cognitively impaired older adults. Future studies are needed to better understand the physiologic underpinnings in age-related and disease-specific decrements in processing speed, and to address the problems in the assessment of processing speed in clinical samples .