Intellectual functioning in renal failure and chronic dialysis.

The research literature on intellectual functioning in uremia and maintenance hemodialysis for renal failure is critically reviewed. The most frequently assessed neuropsychological functions have been general intelligence, memory, and attentional processes. Studies have consistently found lowered performance IQ scores compared to verbal IQ scores in renal failure patients prior to dialysis onset, suggesting the presence of intellectual deficit due to cortical dysfunction. The role of intelligence in adjustment to dialysis has not been clearly explicated, due in part to methodological variations among studies. Several studies point to significant improvement in short-term memory both after onset of maintenance dialysis and from one day before to one day after an individual dialysis treatment session. Attentional functions appear to improve after onset of dialysis treatment as well, but small sample sizes limit the conclusiveness of the data on these cortical processes. Future research efforts should be aimed at correlating physiologic with neuropsychological data and at longitudinal study of intellectual functioning in dialysis patients.