How strongly is delirium correlated with long-term cognitive decline: could it be a cause of cognitive impairment?
Delirium is an acute state of disorientation. Hypoactive delirium (listless, taciturn, mildly confused) more commonly presents than hyperactive delirium (anxious and agitated) in older adults. A recent study published in the Journal of the American Medical Association (Neurology) suggests that managing and reducing incidents of delirium as well as shortening their duration may be important for management long-term cognitive decline. Further, it suggests it is important for physicians to consider delirium as an independent risk factor for future long-term cognitive decline, both in surgical and nonsurgical patient populations.
New Meta-Analysis on Delirium’s Association with Cognitive Decline
Meta-analysis of 23 studies dating from 1965 to 2018 provided evidence that delirium was associated with long-term cognitive decline. Terry E. Goldberg, Ph.D. from the Columbia University Irving Medical Center and colleagues undertook a comprehensive literature review (3,562 patients who experienced delirium, with 6.9K controls) to investigate whether an episode of delirium remains an independent risk factor for long-term cognitive impairment.
For all patients, those who had experienced delirium were almost two and half times more likely to show cognitive decline up to 3 months later, compared with patients who had not. For the surgical patient group, the findings ran counter to the widely held perspective that post-operative delirium is not a risk factor for cognitive decline, but a byproduct of surgical anesthesia/compromise. The circumstances of the delirium (anesthesia, trauma, hypoxia, sepsis or respiratory failure, etc.) did not affect the probability of future cognitive decline. This appears to suggest that the underlying mechanisms of delirium “may be similar and possibly associated with inflammatory processes common to both surgical and nonsurgical contexts,” the study’s investigators noted.
“Causality cannot be confirmed because the studies were designed as observational in demonstrating associations,” Goldberg et al wrote. However, the analyses were consistent with the causal hypothesis. Future findings from “prospective randomized clinical trials, albeit difficult to implement, might help to resolve this issue.” The data suggest that additional research to yield reductions in delirium would, in turn, aid in improving post-delirium cognitive decline.
Assessing Delirium while Assessing Brain Health
Risk factors for episodes of delirium share much in common with the risks for chronic cognitive impairment, in general: history of dementia, sensory impairment, elderly, resident at a nursing care facility, and sepsis. What the Goldberg study suggests is that an episode of delirium, even if entirely explicable, could be regarded as incipient cognitive decline. A one-time assessment after an episode will be insufficient: ongoing testing and a monitoring protocol for the patient after a delirium episode is advisable for prevention and care of cognitive impairment.
As an example, prior to surgery, obtaining a baseline cognitive assessment on the chart will be useful for comparison, should post-op recovery include delirium. After such an episode, tracking and testing should be administered by care staff until discharge, and ongoing assessment beyond.
Delirium is an independent risk factor for long-term cognitive decline. As physicians check patients for “chemo fog” and other presentations of a delirious state, having a proven tool at hand for long-term assessment may be important to mitigate significant cognitive impairment later in life. Optimal identification of cognitive impairment within the primary care setting requires a very quick and user-friendly tool combining patients’ subjective impairments and cognitive testing. Our BrainCheck mobile screening platform is widely used, reimbursable, and efficient for providers, health systems and senior organizations
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Goldberg TE, Chen C, Wang Y, et al. Association of Delirium With Long-term Cognitive Decline: A Meta-analysis. JAMA Neurol. Published online July 13, 2020. doi: 10.1001/jamaneurol.2020.2273.