Background: Studies have linked low blood pressure (BP) with adverse outcomes in CKD. Hypertension is treated to reduce cardiovascular events, however this may compromise cerebral perfusion by excessive lowering of blood pressure.

Objectives: To examine the relationships between ambulatory BP with cognitive performance.

Methods: 80 patients >65 years with CKD were recruited and were assessed using a range of neuropsychological tests. Scores were compared to daytime ambulatory BP. Linear correlations and multivariate regression analysis were used to measure associations. Results were recorded for those with a history of cardiovascular disease (CVD).

Results: 16 patients had a history of CVD. Mean age was 75.7 years (SD 5.8) and 75% were male. Mean BP was 123/70mmHg (SD 14.0/18.0). Univariate correlations showed an increase in BP was positively correlated with cognitive scores. Increasing systolic (B0.35 CI 0.11,0.6 p<0.01) and mean arterial BP (B0.72 CI 0.33,1.12 p<0.01) were predictive of improved Digit-Symbol Substitution test after correcting for age, while increasing systolic (B0.52 CI 0.16,0.89 p<0.01) and mean arterial BP (B0.77 CI 0.15,1.4 p=0.02) was predictive for improved Test of Every Day Attention (Map 1^st min). Although diastolic BP was associated with MMSE (p=0.01), this was not significant when corrected for IQ.

Conclusion: Our results show that in patients with CVD an increase in BP was associated with better scores on tests of global cognition, attention and speed of processing. This raises the possibility that elderly people with CKD and cardiovascular disease may be vulnerable to cognitive impairment with aggressive lowering of blood pressure.