B-CRF : neurological complications
F-08 : Neurological complications
The prevalence, severity, and association with HbA1c and
fibrinogen of cognitive impairment in chronic kidney disease
Ulla K Seidel1, Janine Gronewold1, Michaela Volsek2, Olga Todica1, Andreas Kribben2,
Heike Bruck2 and Dirk M Hermann1
Kidney International (2014) 85, 693–702
1Department of Neurology, University Hospital Essen, Essen, Germany
2Department of Nephrology, University Hospital Essen, Essen, Germany
Correspondence: Dirk M. Hermann, Department of Neurology, University Hospital Essen,
Hufelandstr. 55, 45122 Essen, Germany. Email: dirk.hermann@uk-essen.de
ABSTRACT
Cognitive impairment is a frequent finding in patients with chronic kidney disease (CKD). We
examined cognitive performance in a prospective study of 119 patients with CKD stages 3–5
(including dialysis) and 54 control patients of the same age without CKD but with similar
vascular risk profiles. Analysis included a comprehensive test battery evaluating memory,
information processing speed, executive function, language, and visuoconstructive function,
in addition to depression and anxiety. Thirty percent of patients with CKD had cognitive
deficits (one or more s.d. below control patient performance). Cognitive deficits (T-value
related to published norm values) were mild but significantly decreased to 48.8 in patients
with stage 3–5 CKD not requiring hemodialysis and 47.2 in patients with stage 5D disease
requiring hemodialysis, compared with 51.5 in control patients. Linear regressions among
patients with CKD (forced entry strategy) showed that age (β=−0.50 per s.d.), HbA1c
(β=−0.18 per s.d.), and fibrinogen (β=−0.18 per s.d.) predicted cognitive performance.
Interestingly, HbA1c discriminated cognition in all age groups, while fibrinogen differentiated
cognition particularly in patients over 70 years of age. Thus, our cross-sectional study
suggests the severity of cognitive impairment in CKD is mild. As such, longitudinal studies
are required to further characterize the role of cognitive deficits in CKD.
Keywords: cognition; executive function; memory; vascular risk factor
COMMENTS
Chronic kidney disease (CKD) is a worldwide growing health problem that is found in 23–
35% of adults above 64 years. CKD is frequently associated with cognitive deficits. In
previous studies, 17–50% of CKD patients exhibited impairments in memory, executive
functioning, information processing, or language abilities, depending on CKD stage.2, 3, 4, 5
In end-stage renal disease requiring hemodialysis, >85% of patients had memory, executive
function, or language deficits
It is well established that cognitive deficits are most pronounced in advanced CKD stages. It
has been hypothesized that cognitive impairment results from microvascular dysfunction that
is related to the patients’ vascular risk profiles.
To characterize neuropsychological deficits in CKD, the authors prospectively and
comprehensively studied cognitive performance in 119 patients with CKD stages 3–5 and
compared the results with 54 control patients of the same age without CKD with similar
vascular risk profile
Memory and cognition were studied through a battery of 10 tests that evaluated memory,
information processing speed, executive function, language, and visuoconstructive abilities.
Global cognitive performance, which was evaluated using z-scores computing means for all
10 tests, was significantly worse in stage 3–5 (−0.6±0.8) and stage 5D (−0.5±0.9) patients
compared with control (0.0±0.6) patients. To evaluate predictors of neuropsychological
deficits, univariate and multivariable linear regressions were computed for the whole cohort
(both control and CKD patients), in which the factors age, gender, education, CKD stage,
systolic blood pressure, dyslipidemia, glycated hemoglobin (HbA1c), smoking, body mass
index, brain–derived natriuretic peptide, fibrinogen, depression, anxiety, IMT, ABI, and
history of coronary heart disease, stroke/TIA, and peripheral vascular disease were inserted
either alone or in different combinations
In a multivariable regression (forced entry strategy), in which the factors age, gender,
education, and CKD stage were included, the factors age (β=−0.48 per s.d.; P<0.001),
education (β=0.23 per s.d.; P=0.001), and CKD stage (β=−0.24 per s.d.; P<0.001) were the
predictors of global cognitive performance.
When the vascular risk factors and the inflammation marker fibrinogen or vascular risk
factors, the inflammation marker fibrinogen, depression, and anxiety were also inserted into
the regression analysis, HbA1c turned out as an additional cognitive predictor.
Taken together, this study suggests that associated vascular risk factors and inflammatory
responses rather than the severity of renal disease influence cognitive performance in CKD
patients. Longitudinal studies are warranted to further characterize the role of cognitive
deficits in CKD.
Pr. Jacques CHANARD
Professor of Nephrology