Cognitive impairment in patients with renal failure is associated with multiple-infarct dementia

Patients undergoing long-term renal replacement therapy (such as dialysis) have an increased risk for significant cognitive impairment, which may result in memory problems and subsequently missed attendance at dialysis. The aim of this study was to try to identify any abnormalities of cerebral perfusion that could explain a patient's cognitive impairment and to determine if the pattern of these abnormalities would suggest a cause.

17 patients (13 men; mean age, 60 years; age range, 29-74 years) in end-stage renal failure or on dialysis had SPECT imaging 10 minutes after injection of 550 MBq (15 mCi) Tc-99m HMPAO. Two of the patients had a history of previous stroke. Other risk factors for stroke were noted in most of the patients (hypertension in 10 patients, smoking or former smoking in 10 patients, and cardiac atherosclerosis in 7 patients). In all patients, attenuation correction was applied and the images were reconstructed into three sets of orthogonal slices. Activity in the frontal and temporal lobes was compared by quantification against the ipsilateral and contralateral cerebellum.

Discrete cortical defects consistent with infarcts were seen in 14 patients. The mean right and left frontal-to-cerebellar ratio was 0.837 (SD, 0.09) and 0.837 (SD, 0.08), respectively. This was not significantly different from the right and left temporal-to-cerebellar ratios of 0.843 (SD, 0.07) and 0.848 (SD, 0.07), respectively. Both were within normally accepted ranges.

Patients in end-stage renal failure who also had cognitive impairment appear to have a high number of cortical defects consistent with infarcts (suggesting a multiple-infarct type of dementia). There was no evidence of Alzheimer-type dementia.