“These findings are exciting because they suggest depression truly is a risk factor for dementia, ” said researcher Robert S. Wilson, PhD, of Rush University Medical Center, Chicago. “And if we can target and prevent or treat depression and causes of stress, we may have the potential to help people maintain their thinking and memory abilities into old age.”
Dr. Wilson and colleagues studied 1,764 older adults over an average of eight years, annually evaluating them for depression as well as cognitive ability. During the course of the study, 680 participants died. Researchers performed autopsies on 582 to looks for plaques and tangles to identify dementia and other damage in the brain.
By the study’s end, 922 participants (52%) developed mild cognitive impairment, and 315 (18%) developed dementia. While both mild cognitive impairment and dementia were associated with higher levels of depression before diagnosis (after dementia onset, depression symptoms tended to decline rapidly), researchers found no relationship between the level of depressive symptoms and the amount of damage in the brain.
Dementia-related brain changes were also unrelated to how participants’ depression symptoms changed over time, researchers reported. Participants with mild cognitive impairment were no more likely than participants without mild cognitive impairment, researchers found, to experience a change in depression symptoms after diagnosis.
Overall, higher levels of depression symptoms were associated with a more rapid decline in cognitive impairment, researchers reported, “accounting for 4.4% of the variability in decline not attributable to the neuropathologic markers.”
1. Wilson RS, Capuano AW, Boyle PA, et al. Clinical-pathologic study of depressive symptoms and cognitive decline in old age. Neurology. 2014 July 30. [Epub ahead of print].
2. How is depression related to dementia? [press release]. American Academy of Neurology: Minneapolis; July 30, 2014.