Delirium is a strong risk factor for dementia and death in older people, a study published Wednesday found.
The risk of dementia being diagnosed was three times higher in hospitalized patients who had at least one episode of delirium compared with those who had not. Each additional delirium episode increased the risk by 20%, the report showed.
Previous research has suggested a link between dementia and delirium, but there has not been anything conclusive.
The study published in The BMJ detailed data from 626,467 participants in Australia who were aged more than 65 years and did not have dementia. The participants had been admitted to the hospital between 2009 and 2014. Of them, 55,211 had at least one episode of delirium and were matched to another 55,211 patients without delirium. The people were matched on factors such as age, sex, frailty status, reason for being in the hospital, length of stay in the hospital, and how long they stayed in the intensive care unit.
The researchers followed up on the participants for five years to see how many later received a diagnosis of dementia. During that time, 58% of them died, and dementia was diagnosed in 17% of them.
People with delirium had a 39% higher risk of death and three times the risk of receiving a dementia diagnosis compared with participants who didn’t experience delirium. The relationship between delirium and dementia was more significant in men compared with women, the data showed.
Although the findings don’t show that delirium causes dementia, the researchers pointed out that the study was large and had a substantial follow-up period.
“While our results are consistent with the hypothesis that delirium plays a causative part in dementia, they are not conclusive owing to the fundamental limitations of observational studies in determining causality,” the authors wrote. “Nevertheless, the results of this study provide valuable insights because prospective randomized controlled trials are unlikely to be conducted.”
