Comorbidity and the rate of cognitive decline in patients with Alzheimer dementia

Abstract

This study aimed to investigate the impact of comorbidity on cognitive and functional decline in patients with Alzheimer dementia (AD). One hundred and two AD outpatients examined at the Psychiatry Department of the CF2 Polyclinic in Bucharest, Romania and re-evaluated after 2 years. Comorbidity was rated using the Cumulative Illness Rating Scale for Geriatrics (CIRS-G). Baseline mean age (SD) was 75.4 (8.2) years, median CDR (range) was 2 (1-3), and mean MMSE (SD) 14.2 (4.9). MMSE declined to 11.2 (4.8) during follow-up. Baseline mean total CIRS-G score (SD) was 13.8 (5.4), median number of endorsed categories (range) was 8 (1-14), and mean severity index (SD) 1.9 (0.4). Main comorbidity areas were cardiovascular, ear, nose and throat, genitourinary, musculoskeletal/integument, and neurological. Severity of comorbidity increased with dementia severity (p <0.001). Baseline comorbidity was related to increased rate of cognitive decline; truncated regression coefficients (p-values) were 0.01 (0.02) for CIRS-G total score, and 0.15 (0.006) for severity index (controlled for age, sex, education, and AD treatment). Faster cognitive decline was associated with faster functional decline: OR (95% CI) was 5.2 (1.9-13.6) for increased rate of ADL change and 3.8 (1.0-14.1) for increased rate of IADL change (controlled for age, sex, education, AD medication, and comorbidity). Comorbidity tended to increase functional decline; however, the associations were not statistically significant. In this group of patients with AD, comorbidity increased the rate of cognitive decline. Considering comorbidity instead of focusing on separate conditions may be more helpful in managing AD.