Cognition in chronic kidney disease: a systematic review and meta-analysis

Abstract

BackgroundCognitive impairment is common in people with chronic kidney disease (CKD) and associated with increased morbidity and mortality. Subtle changes can impact engagement with healthcare, comprehension, decision-making, and medication adherence. We aimed to systematically summarise evidence of cognitive changes in CKD.MethodsWe searched MEDLINE (March 2016) for cross-sectional, cohort or randomised studies that measured cognitive function in people with CKD (PROSPERO, registration number CRD42014015226). The CKD population included people with eGFR < 60 mL/min/1.73 m2, not receiving renal replacement therapy, in any research setting. We conducted a meta-analysis using random effects, expressed as standardised mean differences (SMD) with 95% confidence intervals (CI). Outcomes were performance in eight cognitive domains. Bias was assessed with the Newcastle-Ottawa Scale (NOS).ResultsWe identified 44 studies reporting sufficient data for synthesis (51,575 participants). Mean NOS score for cohort studies was 5.8/9 and for cross-sectional 5.4/10. Studies were deficient in NOS outcome and selection due to poor methods reporting and in comparison group validity of demographics and chronic disease status. CKD patients (eGFR < 60 mL/min/1.73 m2) performed worse than control groups (eGFR ≥ 60 mL/min/1.73 m2) on Orientation & Attention (SMD –0.79, 95% CI, –1.44 to –0.13), Language (SMD –0.63, 95% CI, –0.85 to –0.41), Concept Formation & Reasoning (SMD –0.63, 95% CI, –1.07 to –0.18), Executive Function (SMD –0.53, 95% CI, –0.85 to –0.21), Memory (SMD –0.48, 95% CI, –0.79 to –0.18), and Global Cognition (SMD –0.48, 95% CI, –0.72 to –0.24). Construction & Motor Praxis and Perception were unaffected (SMD –0.29, 95% CI, –0.90 to 0.32; SMD –1.12, 95% CI, –4.35 to 2.12). Language scores dropped with eGFR (<45 mL/min/1.73 m2 SMD –0.86, 95% CI, –1.25 to –46; 30 mL/min/1.73 m2 SMD –1.56, 95% CI, –2.27 to –0.84). Differences in Orientation & Attention were greatest at eGFR < 45 mL/min/1.73 m2 (SMD –4.62, 95% CI, –4.68 to –4.55). Concept Formation & Reasoning differences were greatest at eGFR < 45 mL/min/1.73 m2 (SMD –4.27, 95% CI, –4.23 to –4.27). Differences in Executive Functions were greatest at eGFR < 30 mL/min/1.73 m2 (SMD –0.54, 95% CI, –1.00 to –0.08).ConclusionsCognitive changes occur early in CKD, and skills decline at different rates. Orientation & Attention and Language are particularly affected. The cognitive impact of CKD is likely to diminish patients’ capacity to engage with healthcare decisions. An individual’s cognitive trajectory may deviate from average.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-016-0745-9) contains supplementary material, which is available to authorized users.

Mild cognitive impairment in older adults with pre‐dialysis patients with chronic kidney disease: Prevalence and association with physical function

“…This underlines the importance of identifying individuals with MCI and provide effective interventions to those in a reversible stage of cognitive dysfunction. In addition, an association between renal function and MCI was confirmed in patients with CKD; thus, targeted screening for MCI in this clinical population is important.…”

“…More recently, CKD has also been identified as a risk factor for declining cognitive function and dementia, even at moderate stages of CKD . Poor cognitive function has been linked to poor health literacy, poor medication adherence, worse physical and mental health, and greater morbidity and mortality . In addition, CKD‐related cognitive impairment affects healthcare decision‐making .…”

Population-Based Cohort Study on Dementia Risk in Patients with Type 1 Diabetes Mellitus

“…Furthermore, orientation, attention, and language are affected. The cognitive impact of CKDs is likely to diminish the capacity of patients to engage with healthcare decisions [13]. Considering the high prevalence of hypertension, heart disease, and CKDs in patients with type 1 DM, these comorbidities could contribute to the link between type 1 DM and dementia.…”

Screening of Cognitive Impairment in the Dialysis Population: A Scoping Review

“…One of the reasons for the recommendation against routine screening is that the majority of older people with mild cognitive impairment do not progress to dementia or that their cognitive function may even improve. However, there is compelling evidence that cognitive impairment occurs early in ESKD [64] and that people on dialysis have worse cognition than the general population [5,64]. Further, in a recent study of dialysis patients with cognitive impairment, there is evidence that cognition declines faster, with effects on the decision-making capacity [68].…”

“…The differences in inclusion and exclusion criteria, depending on the purpose of the study, may also explain the variable prevalence. While the prevalence of cognitive impairment in people on dialysis is not clear, 2 systematic reviews found that people with ESKD with or without dialysis consistently had lower scores, indicating a high likelihood of cognitive impairment [5,64]. …”