Reduced estimated glomerular filtration rate in Alzheimer's disease.
OBJECTIVE
Renal disease is increasingly regarded as an independent risk factor for vascular disease which in itself is believed to influence risk of AD. Alterations in amyloid homeostasis via reduced renal clearance of peripheral beta-amyloid (A|*beta*|) may represent another potential role for variation in renal function leading to increased risk of AD. We sought to examine estimates of glomerular filtration rate in AD and control groups.


METHODS
AD patients were randomly recruited from the Memory Clinic of the Belfast City Hospital (n = 83). Genomic DNA was extracted from peripheral leucocytes and was genotyped for Apolipoprotein E using standard methods. Using creatinine values, age and gender, estimated Glomerular Filtration Rates (eGFR) were calculated using the isotope dilution mass spectrometry (IDMS)-traceable Modification of Diet in Renal Disease (MDRD) Study equation (using the United Kingdom National External Quality Assessment Scheme (UKNEQAS) correction factor). IDMS eGFR values were then compared between AD and control groups.


RESULTS
Significant baseline differences in age, diastolic blood pressure, education level attained and APOE |*epsilon*|4 carriage were noted between cases and controls. The AD group had a significantly lower eGFR versus controls (69 vs 77 ml/min) which persisted after adjustment for possible confounders (p = 0.045).


CONCLUSIONS
This case-control analysis suggests that using a relatively accurate estimate of renal function, patients with AD have greater renal impairment than cognitively normal controls. This may reflect impaired renal clearance of peripheral A|*beta*| or be a marker of shared vascular processes altering cerebral and renal functioning.
Kerr
Enda
E
Queen's University of Belfast, School of Medicine, Belfast BT9 7BL, UK.
Craig
David
D
McGuinness
Bernadette
B
Dynan
Kevin B
KB
Fogarty
Damian
D
Johnston
Janet A
JA
Passmore
A Peter
AP
D000368:Aged; D000544:Alzheimer Disease / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D001057:Apolipoproteins E / Q000097:blood / Q000235:genetics; D016022:Case-Control Studies; D016001:Confidence Intervals; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007674:Kidney Diseases / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D008297:Male; D012307:Risk Factors; D014652:Vascular Diseases / Q000097:blood / Q000150:complications / Q000503:physiopathology*
D001057:Apolipoproteins E; D003404:Creatinine