“Many studies have found that older people with some depression are more likely to develop cognitive decline or dementia,” Robert S. Wilson said.
But there has been disagreement over whether depression actually contributes to cognitive decline or whether both are the result of other underlying problems, he told Reuters Health.
Wilson worked on the study at the Rush Alzheimer’s Disease Center in Chicago.
He and his coauthors analyzed data on 1,700 people over age 50 who initially had no cognitive problems and were followed for an average of eight years. Each year doctors evaluated participants’ depression symptoms and tested their thinking and memory skills.
About half of the original group developed mild cognitive impairment, which often comes before dementia, and 18 percent were diagnosed with dementia.
Participants who had more depression symptoms on their initial exams were more likely to experience cognitive decline.
Depression symptoms were also linked to dementia and to more rapid decline after a dementia diagnosis, according to results published in Neurology.
Almost 600 of the participants died during the study and their brains were examined postmortem.
Among those participants, depression was still associated with faster mental decline when amyloid plaques – considered the hallmarks of Alzheimer’s disease – and other neuropathological problems found on autopsy were taken into account.
“Late life dementia is a very complex disorder and there are many factors that contribute to it, and depression is one of those factors,” Wilson said.
Depression accounted for five percent of the variability in mental decline that couldn’t be attributed to other problems with the brain, he said.
Depression symptoms did not increase once cognitive decline started, and actually decreased once dementia was diagnosed. Depression itself is an organized process of the brain, and as brain function declines it is common for people to experience periods of unhappiness but it is rare that those periods are consistent, Wilson said. […]
Read the full story on Reuters.