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Depressive symptoms linked to cognitive decline

New study results published in Neurology suggest that depressive symptoms are linked to cognitive decline.

“Studies have shown that people with symptoms of depression are more likely to develop dementia, but we haven’t known how the relationship works,” Robert S. Wilson, PhD, a neuropsychiatrist at the Rush Alzheimer’s Disease Center in Chicago, said in a press release. “Is the depression a consequence of the dementia? Do both problems develop from the same underlying problems in the brain? Or does the relationship of depression with dementia have nothing to do with dementia-related pathology?”

Wilson and colleagues evaluated 1,764 adults aged at least 50 years without cognitive impairment to determine whether a link exists between dementia. Participants were followed up for an average of 7.8 years.

Overall, depressive symptoms increased over time (P<.001).

More than half (52.2%) of participants developed mild cognitive impairment during follow-up. These participants were commonly older and more educated at baseline compared with those who did not develop mild cognitive impairment.

Dementia developed in 17.9% of participants during follow-up. Compared with those who did not develop dementia, those who did were older and more depressed at baseline.

“Depressive symptoms were associated with rates of cognitive decline, and after adjustment for postmortem markers of six types of dementia-related pathology, huger levels of depressive symptoms during the study period remained associated with faster rates of cognitive decline, accounting for 4.4% of the variability in rates of cognitive decline not attributable to neuropathologic burden,” the researchers wrote.

They added that the results add to previous studies “by showing that depressive symptoms have an association with cognitive decline that is independent of the neuropathologic conditions most strongly linked to late-life cognitive decline and dementia.”

Disclosure: See the study for a complete list of the researchers’ financial disclosures.