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

OBJECTIVE: This study aimed to investigate the impact of comorbidity on cognitive and functional decline in patients with Alzheimer dementia (AD). METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.