Moderate to severe cognitive impairment is common and undiagnosed in hemodialysis patients. Further studies are needed to determine whether dialysis exacerbates the cognitive impairment attributable to underlying disease. Cognitive testing in hemodialysis patients before dialysis initiation and periodically may be warranted.

Background Prevalence of moderate to severe cognitive impairment among hemodialysis patients is more than double the prevalence in the general population. This study describes cognitive impairment occurrence in a peritoneal dialysis cohort compared with a cohort without chronic kidney disease (CKD). Study Design Cross-sectional study. Setting and Participants 51 English-speaking peritoneal dialysis patients from two urban dialysis units, compared with 338 hemodialysis patients from 16 urban dialysis units and 101voluntary controls without CKD from urban general medicine clinics. Predictor A 45-minute battery of nine validated neuropsychological tests (cognitive domains memory, executive function, language). Outcomes Mild, moderate, or severe cognitive impairment, classified according to a previously designed algorithm. Results Of the peritoneal dialysis cohort, 33.3% had no or mild, 35.3% moderate, and 31.4% severe cognitive impairment; corresponding values were 60.4%, 26.7%, and 12.9% of the non-CKD cohort, and 26.6%, 36.4%, and 37.0% of the hemodialysis cohort. A logistic regression model including age, sex, race, education, hemoglobin, diabetes, and stroke showed that only non-white race (P = 0.002) and education (P = 0.002) were associated with moderate to severe cognitive impairment in the peritoneal dialysis cohort. Compared with hemodialysis patients, more peritoneal dialysis patients had moderate to severe memory impairment (60% vs. 52%), but fewer had impaired executive function (one-third vs. one-half). Peritoneal dialysis was associated with a more than 2.5-fold increased risk of moderate to severe cognitive impairment compared with no CKD (OR, 2.58; 95% confidence interval 1.02-6.53), as was hemodialysis (OR, 3.16; 95% CI, 1.91-5.24), in an adjusted logistic regression model. Limitations Small sample size, participation rate somewhat low. Conclusions Similar to hemodialysis patients, two-thirds of peritoneal dialysis patients had moderate to severe cognitive impairment, enough to interfere with safely self-administering dialysis and adhering to complex medication regimens. These patients could benefit from cognitive assessment before and periodically after dialysis initiation.

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Driving after use of marijuana is almost as common as driving after use of alcohol in youth (P. M. O'Malley & L. D. Johnston, 2003). The authors compared college students' attitudes, normative beliefs and perceived negative consequences of driving after use of either alcohol or marijuana and tested these cognitive factors as risk factors for substance-related driving. Results indicated that youth perceived driving after marijuana use as more acceptable to peers and the negative consequences as less likely than driving after alcohol use, even after controlling for substance use. Results of zero-inflated Poisson regression analyses indicated that lower perceived dangerousness and greater perceived peer acceptance were associated with increased engagement in, and frequency of, driving after use of either substance. Lower perceived likelihood of negative consequences was associated with increased frequency for those who engage in substance-related driving. These results provide a basis for comparing how youth perceive driving after use of alcohol and marijuana, as well as similarities in the risk factors for driving after use of these substances.

Background The Brain in Kidney Disease (BRINK) Study aims to identify mechanisms that contribute to increased risk of cognitive impairment (CI) in chronic kidney disease (CKD) patients. We describe the rationale, design, and methods of the study and report baseline recruitment and cognitive function results. Study Design Longitudinal observational cohort study of the epidemiology of CI in CKD. The primary aim is to characterize the association between (a) baseline and incident stroke, white matter disease, estimated glomerular filtration rate (eGFR), inflammation, microalbuminuria, dialysis initiation, and (b) cognitive decline over 3 years in a CKD cohort with mean eGFR < 45 mL/min/1.73 m2. Setting & Participants Community-dwelling participants aged 45 years or older recruited from four health systems into two groups: reduced eGFR, defined as eGFR < 60 mL/min/1.73 m2 (non-dialysis-dependent), and control, defined as eGFR ≥ 60 mL/min/1.73 m2. Predictor eGFR group. Outcomes Performance on cognitive function tests and structural brain magnetic resonance imaging. Measurements Sequential cognitive and physical function testing, serum and urine biomarker measurement, and brain magnetic resonance images over 3 years. Results Of 554 participants, mean age was 69.3 years; 333, 88, and 133 had eGFR <45 (non-dialysis dependent, non-transplant), 45-<60, and ≥ 60 (controls) mL/min/1.73 m2, respectively. Mean eGFR in the reduced eGFR participants was 34.3 mL/min/1.73 m2. Baseline cognitive performance was significantly associated with eGFR in all domains except language. Participants with eGFR < 30 mL/min/1.73 m2 performed significantly worse than those with eGFR ≥ 30 mL/min/1.73 m2 on tests of memory, processing speed, and executive function. Participants with reduced eGFR overall scored worst on the Immediate Brief Visual-Spatial Memory Test-Revised. Limitations Healthy cohort bias, competing risk of death versus cognitive decline. Conclusions Cognitive function was significantly worse in participants with eGFR < 30 mL/min/1.73 m2. Future BRINK analyses will measure risk factors for cognitive decline using the longitudinal data.