Kidney Function, Cognitive Impairment, and Trajectories: A Longitudinal Biracial Study.

BACKGROUND

Chronic kidney disease (CKD) is associated with incident cognitive impairment (ICI) and disproportionately affects older adults and Black persons.

OBJECTIVE

To determine (1) whether age or race differences exist in the association of CKD and ICI and (2) whether cognitive trajectories differ in people with and without CKD.

DESIGN

Nationwide cohort study.

PARTICIPANTS

A total of 22,435 Black and White adults age ≥ 45 years without baseline cognitive impairment.

MEASUREMENTS: Creatinine-cystatin C-based eGFR and albumin-to-creatinine ratio (ACR). Six-item screener (SIS) of global cognition every 6 months, three cognitive domain tests (memory, semantic, and letter fluencies) every 2 years for 10 years. Logistic regression for risk of CI and latent growth curve models for trajectory analysis.

RESULTS

Participants were 56% female, 37% Black, 56% hypertensive, and 19% had diabetes. Overall, 13% (n = 2959) developed ICI over 10 years. In mid-life (age 45- < 65), the OR (95% CI) of ICI for eGFR < 45 vs eGFR ≥ 90 was 1.9 (1.2, 3.0); in late-life (≥ 65), the OR was 0.9 (0.7, 1.1), p interaction < 0.001. For ACR > 300 vs ACR < 10, in mid-life and late-life, the ORs were 1.6 (1.0, 2.6) and 1.0 (0.7, 1.4), p interaction 0.02. Compared to those with eGFR ≥ 60, eGFR < 60 was associated with lower initial cognitive domains scores, worse in mid-life than late-life, but the slopes did not differ. Compared to ACR < 30, ACR ≥ 30 had lower initial cognitive domain scores, which were similar in mid and late-life, and a steeper decline for memory scores. No differences by race were observed.

CONCLUSIONS

Kidney disease was more strongly linked to cognitive impairment in mid-life than in late-life. Albuminuria was associated with steeper decline in memory function, especially in mid-life.

PRIMARY FUNDING SOURCE: NIGMS.