Disability in older adults across the continuum of cognitive decline: unique contributions of depression, sleep disturbance, cognitive deficits and medical burden.

Depressive symptoms account for a significant portion of the variance in disability, but other factors such as age, medical burden and sleep quality are also important contributors in older adults across the continuum of cognitive decline. The relative association of these variables with disability appears to differ for older (≥65 years) relative to younger (<65 years) participants. Given the relationship between disability and these risk factors, an integrative and multidisciplinary approach to risk reduction will likely be most effective, with potential carry over effects for physical and mental health.