HealthDay News — For older adults, depressive symptoms are associated with cognitive decline but appear independent of the neuropathologic hallmarks of dementia, according to a study published online in Neurology.

Robert S. Wilson, PhD, from the Rush Alzheimer’s Disease Center in Chicago, and colleagues conducted a clinical-pathologic cohort study involving 1,764 older persons without cognitive impairment at enrollment. The authors sought to examine the correlation between depressive symptoms and dementia. Participants completed annual clinical evaluations for a mean of 7.8 years, including depressive symptom assessment and cognitive function evaluation. During follow-up, 582 individuals died and underwent neuropathologic examination.

The researchers found that during follow-up there was a slight increase in the level of depressive symptoms. Incident mild cognitive impairment (developed by 52.2% of the cohort) correlated with higher level of depressive symptoms before onset, but not with the rate of post-diagnosis symptom change. A total of 17.9% of participants developed dementia; the level of depressive symptoms was higher before dementia onset and dementia onset correlated with more rapid decline in depressive symptoms.

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There was no correlation between any neuropathologic markers with levels of depressive symptoms or change in symptoms over time. After adjustment for neuropathologic markers, higher level of depressive symptoms correlated with more rapid global cognitive decline, accounting for 4.4% of the variation in decline that was not due to changes in neuropathologic markers. The association of neuropathologic markers with cognitive decline was not modified by depressive symptoms.

“In old age, depressive symptoms have an association with cognitive decline that is independent of the neuropathologic hallmarks of dementia,” the authors write.

Several authors disclosed financial ties to the pharmaceutical and biotechnology industries.