Assessing Cognition in CKD Using the National Institutes of Health Toolbox.

Key Points: Participants with CKD had detectable cognitive deficits in fluid cognition, dexterity, and total cognition. Sex differences in cognition exist in people with CKD.

Background: CKD is largely an age-related clinical disorder with accelerated cognitive and cardiovascular aging. Cognitive impairment is a well-documented occurrence in midlife and older adults with CKD and affects multiple domains. We examined cognition function and potential sex differences in cognition in adults with CKD.

Methods: We included 105 individuals (49.5% women) with CKD stage 3b–4 (eGFR, 15–44 ml/min) from the Bicarbonate Administration in CKD Trial (NCT02915601). We measured cognitive function using the National Institutes of Health Toolbox Cognition Battery, which assesses cognitive and motor measures, such as executive function, attention, memory, and dexterity. All study measures were collected and analyzed at the study baseline.

Results: The mean (SD) age and eGFR were 61±12 years and 34.9±9.8 ml/min per 1.73 m. Overall, when compared with the National Institutes of Health Toolbox reference population, participants scored, on average, below the 50th percentile across all cognitive domain tests and the dexterity test. Total cognition scores were also below the 50th percentile. Participants with stage 4 CKD had significantly lower fluid cognition scores compared with those with CKD stage 3b (-estimate −5.4 [95% confidence interval, −9.8 to −0.9]; = 0.03). Female participants with CKD performed significantly better on the episodic memory tests and dexterity tests (dominant and nondominant pegboard tests) and had higher crystallized cognition scores, on average, compared with male participants.

Conclusions: Participants with CKD had detectable cognitive deficits in fluid cognition, dexterity, and total cognition. In addition, sex differences in cognitive measures were found among people with CKD.