Inclusion of an Informant Yields Strong Associations between Cognitive Complaint and Longitudinal Cognitive Outcomes in Non-Demented Elders

Abstract

Background:

The relation between the source of cognitive complaint and objective cognitive performance is not well understood.

Objective:

Examine self and informant cognitive complaint as predictors of objective cognitive and functional trajectory in non-demented elders.

Methods:

Participants from the National Alzheimer's Coordinating Center had a baseline diagnosis of normal cognition (NC; n = 6133, 72 ± 8 years, 68% female) or mild cognitive impairment (MCI; n = 3010, 74 ± 8 years, 55% female). Four independent groups defined cognitive complaint: no complaint, self-only complaint, informant-only complaint, or mutual complaint (both self and informant complaint). Linear mixed model regression analyses related complaint status (referent was no complaint) to cognitive and functional trajectories, adjusting for age, sex, race, education, and follow-up period.

Results:

Among NC participants, mutual complaint related to faster decline in global cognition (p < 0.0001), language (all p-values <0.0001), processing speed (p = 0.0002), and executive functioning (p = 0.0006). Informant-only complaint related to faster decline in global cognition (p = 0.0001) and processing speed (p = 0.0001). Self-only complaint related to greater decline in immediate (p < 0.0001) and delayed (p = 0.0005) episodic memory. In MCI, mutual complaint related to faster decline in global cognition (p < 0.0001), verbal episodic memory (all p-values <0.0001), language (all p-values <0.0001), and processing speed (all p-values <0.0006). Informant-only or self-only complaint associations with cognitive trajectory did not survive correction factor for multiple comparisons.

Conclusion:

Cognitive complaint appears to have clinical significance, as it is related to declines in objective cognitive performance over time. Mutual complaint was associated with the worst cognitive trajectory in both NC and MCI elders, highlighting the importance of incorporating an informant into evaluation of elders whenever feasible.