A new study in Boston has found growing evidence that for older patients, experiencing delirium after surgery may be linked to long-term cognitive decline, which is a known marker for Alzheimer's disease.
Delirium is a common, yet serious and often deadly disorder that affects as many as 50 percent of older people during the period of hospitalization and surgery. Experts from Boston say this disorder costs more than $164 billion annually.
And until now, the association between delirium and long-term mental decline has not been well-studied.
The new study — which was conducted by the Harvard Medical School in affiliation with Hebrew SeniorLife Institute for Aging Research (IFAR), the Beth Israel Deaconess Medical Center, Northeastern University and Brown University — evaluates the trajectory of both long-term and short-term cognitive decline in patients who suffered delirium in the course of 36 months after surgery.
The participants in the study, aged 70 years old and above, showed no signs of dementia and had to undergo surgery with a scheduled stay of three days long or more.
Findings Of The Study
Researchers discovered that delirium occurred in 134 out of 560 study participants.
In the end, both participants who experienced delirium and those who did not experience it had showed a significant cognitive decline during the first month, trailed by a recovery above baseline during the second month. Then, there was a slow decline for the succeeding 34 months.
However, the group who experienced delirium had a stronger decline at one month compared to the other group. The delirium group recovered after two months, but it had a more significant cognitive decline after the 60-day mark.
After 60 days, both the delirium and non-delirium group experienced cognitive decline on average, but the delirium group showed more.
When the research team compared the changes from baseline to 36 months, there had been no significant change in the non-delirium group, while there was a marked decline for the delirium group.
Possible Explanations
Researchers explained that the fact that both groups experienced cognitive decline during the first month and then returned to baseline at the second month possibly represent the immediate effects of hospitalization, anesthesia and surgery.
However, the rate of cognitive decline after the first month for the patients who suffered delirium may trigger a cascade of events that lead to progressive and long-term impacts.
It may also be that delirium is linked to a pre-existing higher rate of cognitive decline that cannot be detected at baseline. Whichever the case is, researchers say delirium may serve as a marker for the elderly with poor cognitive functions.
Details of the study are published in the journal Alzheimer's & Dementia.
Photo: Acy Varlan | Flickr
