Combination of Delirium and Dementia Linked to High Rate of Cognitive Decline

According to a new study, delirium is associated with accelerated cognitive decline in patients with dementia-related pathological processes.

The study included harmonized data of 987 individual brain donors from 3 observational cohort studies performed from January 1, 1985 through December 31, 2011. There were 682 women included in the study (69%).
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Investigators performed neuropathologic assessments and were masked to the clinical data. Researchers used random-effects linear regression to model and assess the interactions between delirium and the pathologic burden of dementia. Outcomes were measured using the Mini-Mental State Examination scores (MMSE) from 6 years before death to time of death to determine changes in the mental states of participants.

The mean age at death was 90 years, and the mean MMSE score was 24.7 points.

Overall, 279 individuals had delirium and worse initial MMSE scores, (-2.8 points). Cognitive decline attributable to delirium was -0.37 MMSE points per year. Decline attributable to the pathologic processes of dementia was −0.39 MMSE points per year.

The interaction between delirium and the pathologic processes of dementia resulted in the greatest cognitive decline, contributing an additional −0.16 MMSE points per year.

“Therefore, individuals with delirium and high dementia pathologic burden had estimated rates of decline of −0.35 points (base rate), −0.37 points (attributable to delirium), −0.39 points (attributable to pathologic burden), and −0.16 points (attributable to interaction), which equals 1.27 points per year,” the researchers stated.

Their findings are the first to demonstrate the effects of delirium and the pathologic processes of dementia on cognitive decline. Patients with both delirium and pathologic processes of dementia have greater cognitive decline per year than patients with either delirium or with dementia alone.

“Our findings indicate that clinicians need to be alert to older people’s cognitive changes during acute episodes and in follow-up across all settings and therefore support wider implementation of best practice in delirium prevention,” the researchers concluded.

—Melissa Weiss

Reference:

Davis DH, Muniz-Terrera G, Keage HAD, et al. Association of delirium with cognitive decline in late life: a neuropathologic study of 3 population-based cohort studies [published online January 18, 2017]. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2016.3423.