Accuracy of collateral source reports in very mild to mild dementia of the Alzheimer type.

OBJECTIVES

To examine the reporting accuracy of collateral sources (knowledgeable informants) regarding very mild and mild dementia of the Alzheimer type (DAT) and to identify characteristics associated with collateral source accuracy.

DESIGN

Secondary data analysis of initial visits of individuals enrolled in a longitudinal study of healthy aging and Alzheimer disease.

SETTING

Urban Alzheimer disease research center.

PARTICIPANTS

Pairs of 515 individuals with very mild (n = 203) or mild (n = 312) DAT and their collateral sources.

MEASUREMENTS

Collateral sources were asked separately during a semistructured interview by experienced clinicians to report current ability of the individual with DAT in memory, orientation, and judgment and problem solving. The clinical performance of the individuals with DAT in these domains was compared with these predictions.

RESULTS

Collateral sources were consistently and significantly accurate in reporting the cognitive capabilities of individuals with very mild and mild DAT. Although all types of collateral sources performed significantly better than chance, individual variables that correlated with collateral source accuracy included spousal relationship; living with the individual with DAT; frequent exposure to the individual; and age, education level, sex and dementia severity of the individual with DAT.

CONCLUSION

Collateral sources are accurate in reporting the cognitive capabilities of individuals with DAT, even in the very mild stage of dementia.