Delirium and Alzheimer Disease: A Dangerous Duo

A long-standing clinical pearl is that brain injury increases an individual’s vulnerability to the cognitive effects of certain medications and diseases (e.g., infection) and that when the offending agent is removed or the disease has been treated, the individual recovers. To learn whether this is true for delirium in patients with Alzheimer disease, researchers conducted a large prospective study of consecutive patients from a memory-disorders unit in a large academic hospital. The patients were diagnosed with probable or possible AD and were reassessed approximately every 6 months. Of 990 eligible patients, 72 had experienced episodes of delirium, diagnosed through in-hospital chart reviews, at time points allowing for determination of the postdelirium trajectory of cognitive decline; 336 patients without delirium episodes formed the comparison group.

Those with delirium were older (77 vs. 73), more likely to be male (54% vs. 41%), and more likely to have a family history of dementia (11% vs. 4%). Delirium patients also had less education (13 vs. 14 years), more comorbid illnesses (1.7 vs. 1.3), and a shorter duration of symptoms before AD diagnosis (2.6 vs. 3.2 years). The postdelirium group was less cognitively impaired than the nondelirium group. Subsequent analyses controlled for these group differences.

In the postdelirium group, the rate of cognitive decline (measured by a test of information, memory, and concentration) accelerated significantly within 6 months. This rate was approximately three times faster than in the nondelirium group.