Causes of death associated with Alzheimer disease: variation by level of cognitive impairment before death

Abstract

Objective: To describe causes of death for patients with Alzheimer disease (AD) and other dementing illnesses enrolled in a population-based Alzheimer disease patient registry (ADPR) and to describe the variation in causes by the level of cognitive impairment before death in probable AD cases.

Setting: The ADPR enrolls and diagnoses newly recognized potential dementia cases occurring in a large, stable health maintenance organization. To date, 654 cases have been enrolled and followed annually to monitor cognitive decline and verify initial diagnosis.

Design: Longitudinal descriptive study.

Patients: ADPR enrollees who have died.

Measurements: Death certificates were obtained for all who died (total n = 104, probable AD = 55); reported causes of death were reviewed by a physician to determine the underlying cause. AD patients were categorized according to their Mini-Mental State Exam score (cognitive impairment) within 12 months of death as (a) mildly (21+), (b) moderately (15-20), or (c) severely (0-14) impaired, and underlying cause and all reported causes of death for each group were tabulated.

Main results: Among probable AD patients, pneumonia and AD were most often recorded on death certificates when cognitive impairment within the year prior to death had reached the severe level; heart disease, stroke, and other common causes of death predominated in AD patients who were less cognitively impaired.

Conclusions: When AD cases were followed from first diagnosis to death, the causes of death varied by level of cognitive impairment. Illnesses potentially amenable to treatment caused death at all levels of disease, but more so early in the course of AD. Cognitive impairment may make patients less able to recognize and report symptoms of medical problems, thereby complicating efforts to intervene.