Is There a Relationship between Depression and Dementia?
A study by neuropsychiatric researchers at Rush University looked at and dementia and depression. The study is in the July 30, 2014, online issue of Neurology®, the journal of the American Academy of Neurology.
Up until now studies have shown that people with depression are more likely to develop dementia, but it hasn’t been clear how the relationship works. 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? This would suggest depression truly is a risk factor for dementia, and that if we can treat depression and causes of stress there may be the potential to help people maintain their thinking and memory.
The study involved 1,764 people. Participants were screened every year for 8 years for symptoms of depression, such as loneliness. A total of 680 people died during the study. Autopsies were performed on 582 of them to look for the plaques and tangles in the brain that are the signs of dementia along with any other brain damage.
Nine hundred twenty two (922) people, or 52 percent of the participants, developed the mild problems with memory and thinking that is often a precursor to Alzheimer’s. A total of 315 people, or 18 percent, developed dementia.
However, the researchers found no relationship between how much damage was found in the brain and the level of depression people had. There was also no relationship in the change in depression over time. In other words, overt damage in the brain is not directly related to the level of depression.
People who developed mild cognitive impairment were no more likely to have any change in depression than people without MCI. People with dementia were more likely to have a higher level of depression before the dementia started, but they had a more rapid decrease in depression after dementia developed. In other words, depression was an independent risk factor for dementia, but once dementia started there was a better improvement in that depression.
Having a higher level of depression was associated with more rapid decline in thinking and memory skills, accounting for 4.4 percent of the difference in decline that could not be correlated to the level of damage in the brain.
As is usual with the brain, things are more complex than they initially seem to be.