Effect of renal impairment on cognitive function during a 3‐year follow up in elderly patients with type 2 diabetes: Association with microinflammation

Abstract

Aims/IntroductionWe investigated the effect of renal impairment on cognitive function during a 3‐year follow up in elderly type 2 diabetic patients, and an association with microinflammation.Materials and MethodsFour cognitive function tests – Mini‐Mental State Examination (MMSE), word recall, Digit Symbol Substitution (DSS) and Stroop Color Word – were carried out in 67 patients. Renal impairment was defined as the presence of albuminuria and a decline in estimated glomerular filtration (eGFR) <60 mL/min/1.73 m2. Inflammatory markers, such as highly sensitive C‐reactive protein (hs‐CRP), tumor necrotizing factor‐α (TNF‐α), interleukin (IL)‐1β and IL‐6, were measured at baseline.ResultsAt baseline, cognitive decline was found in patients with renal impairment. The DSS test was independently associated with eGFR decline, whereas MMSE tended to be associated with albuminuria after adjusting for confounding factors. Regarding changes in cognitive function and renal impairment, changes in urinary albumin to creatinine ratios were strongly and independently associated with changes in word recall scores. In patients with persistent eGFR decline, there was a tendency toward a greater decrease in MMSE and DSS scores, whereas in those with newly detected albuminuria, there was a tendency toward a greater decrease in word recall scores. Increased baseline levels of hs‐CRP, TNF‐α and IL‐6 were associated with renal impairment and cognitive function, especially DSS tests, respectively. However, the increased levels were not independent predictors for cognitive decline.ConclusionsThe present study showed a reciprocal relationship between cognitive decline and renal impairment, especially progression of albuminuria. Thus, monitoring treatment using renal biomarkers will be important for preserving both renal and cognitive function.

Curious relationship between cognitive impairment and diabetic retinopathy

“…In addition, parallel changes in severity and improvement of chronic kidney disease and some cognitive functions have been reported in the recent subanalysis of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial 5 . In this regard, we reported that changes in albuminuria, but not eGFR, were strongly correlated with changes in word recall during a 3-year follow up in elderly diabetic patients 6 . However, in that study, a cross-sectional evaluation of an association between cognitive functions and albuminuria or eGFR produced different results from those of a longitudinal evaluation.…”

Chronic kidney disease‐related physical frailty and cognitive impairment: a systemic review

“…After adjusting for potential confounders, moderate renal insufficiency was associated with a 37% increased risk of dementia over a median 6 yr follow‐up in individuals without prevalent dementia (n = 3349) . A study of elderly type 2 diabetic patients with a 3‐year follow up showed that renal impairment was also related to cognitive decline . The reduction in the one‐year MMSE was higher in hemodialysis (HD) patients than elderly patients .…”

“…Another survey indicated that the high prevalence of WMH in HD, older age, female patients with high blood pressure was strongly associated with the presence of both PVH and DSWMH . Increased baseline levels of hs‐CRP, TNF‐α and IL‐6 were associated with renal impairment, cerebral SVD and cognitive function . Fibrinogen, an acute‐phase protein and inflammation marker, was elevated in CKD patients, which predicts cognitive performance in CKD and as a marker of late‐life CI .…”

“…33 A study of elderly type 2 diabetic patients with a 3-year follow up showed that renal impairment was also related to cognitive decline. 34 The reduction in the one-year MMSE was higher in hemodialysis (HD) patients than elderly patients. 35 The one-year incidence rate of multi-infarct dementia in aged HD patients was 7.4 times larger than that in the elderly general population.…”

“…61 Increased baseline levels of hs-CRP, TNF-α and IL-6 were associated with renal impairment, cerebral SVD and cognitive function. 34,62 Fibrinogen, an acute-phase protein and inflammation marker, was elevated in CKD patients, which predicts cognitive performance in CKD and as a marker of late-life CI. 63 The Kidney Disease Quality of Life-Cognitive Function Subscale (KDQOL-CF) was inversely correlated with the levels of IL-6, TNF-alpha and IL-10 in HD patients.…”