Objective: To study the relationship between subjective memory complaints, cognitive functioning, and clinical diagnosis of dementia.
Design: Cross-sectional, total-population survey.
Measurements: A two-phase study was done. All 2368 were screened by Mini-Mental State Examination (MMSE). Then the 314 who screened positive and a sample of 354 who screened negative were examined clinically (by examining the subject and interviewing an informant) for DMS-III-R criteria for dementia, Clinical Dementia Rating (CDR) scale for severity of dementia and the presence of memory complaints or depressed mood.
Setting: An area in Stockholm, Sweden.
Participants: All inhabitants of the area (2368) born in 1912 or before, living at home or in institutions.
Results: A greater percentage of informants reported marked memory impairment than did the subjects themselves. Neither the informants' nor the subject' reports differed according to the type of dementia, but they differed clearly according to the stage of dementia. Informants reported memory impairment more frequently as dementia severity increased, while the subjects' complaints of marked memory impairment were most common in mild-moderate dementia. Furthermore, non-demented subjects with marked complaints performed more poorly on the MMSE. Subjects with depressed mood were also more likely to complain about their memory, both in the demented and non-demented groups.
Conclusion: Our data show the validity of the informants' reports about the subjects' memory deficits. Moreover, the study confirmed the clinical impression that the patient's own complaints should not be ignored, as subjects in the mild stage of dementia often have some insight into their own memory deficit. However, depressed individuals may underestimate their own memory, and individuals with moderate-severe dementia may overestimate theirs.