Symptom Patterns and Comorbidity in the Early Stages of Alzheimer's Disease

OBJECTIVE: To learn whether patients with early Alzheimer's disease tend to under-report or over-report symptoms and to compare their comorbidity with non-demented patients. DESIGN: Case Control Study in a population-based dementia registry. SETTING AND PATIENTS: Three groups of subjects (mean age 76) were enrolled from an HMO base population: 154 cases had clinically diagnosed probable Alzheimer's disease, 92 subjects were found to be not demented although they had complaints of cognitive impairment, and another 129 cognitively intact controls were enrolled after frequency-matching for age and sex. MEASUREMENTS AND RESULTS: Medical records were examined for the 2 years prior to enrollment. Symptoms suggestive of cognitive impairment were evident 7.8 months prior to enrollment (median 6 months) in 95% of cases, in 77% of the not demented subjects, and in 6% of controls. After corrections for multiple comparisons, only symptoms of cognitive impairment were more frequent in cases, whereas several common symptoms not suggestive of cognitive impairment (eg, gastrointestinal discomfort, joint pain, vision problems) occurred more often in controls and the not demented group, even though comorbidity was similar among all three groups (Charlson Index mean scores: case = 0.7, not demented = 0.7, control = 0.5). CONCLUSIONS: Persons with Alzheimer's disease do complain of symptoms clearly related to cognitive impairment early in the course of illness, but may under-report common symptoms not suggestive of cognitive impairment, even though their comorbidity is similar to patients without dementia.