Effects Of Age-related Decline Research Articles

Autonomic regulation and maze-learning performance in older and younger adults

There is growing evidence that centrally modulated autonomic regulation can influence performance on complex cognitive tasks but the specificity of these influences and the effects of age-related decline in these systems have not been determined. We recorded pre-task levels of respiratory sinus arrhythmia (RSA; an index of phasic vagal cardiac control) and rate pressure produce (RPP; an index of cardiac workload) to determine their relationship to performance on a cumulative maze learning task. Maze performance has been shown to reflect executive error monitoring capacity and non-executive visuo-motor processing speed. Error monitoring was predicted by RSA in both older and younger adults but by RPP only in the older group. Non-executive processes were unrelated to either measure. These data suggest that vagal regulation is more closely associated with executive than nonexecutive aspects of maze performance and that, in later life, pre-task levels of cardiac workload also influence executive control.

Factors affecting the progression of diabetic nephropathy and its complications: A single-center experience in Saudi Arabia

BACKGROUND AND OBJECTIVES:One out of five Saudi diabetics develops end-stage renal disease (ESRD). Factors associated with progressive loss of renal function have not been extensively studied and reported in our community. We sought to evaluate the pattern and progression in glomerular filtration rate (GFR) and investigate the potential risk factors associated with progression to diabetic nephropathy (DN) among Saudi patients.DESIGN AND SETTING:Hospital-based retrospective analysis of type 2 diabetic patients seen between January 1989 and January 2004 at Security Forces Hospital and King Saud University in Riyadh, Saudi Arabia.PATIENTS AND METHODS:DN was defined as persistent proteinuria assessed by urine dipstick [at least twice for at least two consecutive years and/or serum creatinine >130 μmol/L; and/or GFR <60 mL/min/1.73m2].RESULTS:Of 1952 files reviewed, 621 (31.8%) met the criteria for DN, and 294 (47%) were males. The mean (SD) age of the patients at baseline was 66.9 (11.4) years, and mean duration of diabetes was 15.4 (7.5) years. GFR deteriorated from a baseline value of 78.3 (30.3) mL/min/1.73m2 to 45.1 (24.1) mL/min/1.73m2 at the last visit, with a mean rate of decline in GFR of 3.3 mL/min/year. Progression of nephropathy was observed in 455 (73.3%) patients, with 250 (40.3%) patients doubling their first–hospital-visit serum creatinine level in a mean of 10.0 (6.0) years. At the end of the study, 16.5% of the cohort developed ESRD and were dialyzed. GFR >90 mL/min/1.73m2 at the first hospital visit; duration of diabetes >10 years; persistent proteinuria; systolic blood pressure >130 mm Hg; and presence of retinopathy were significant markers associated with progression of nephropathy.CONCLUSION:Diabetic nephropathy tends to be progressive among Saudis, with GFR deteriorating at a rate of 3.3 mL/year and with a doubling of serum creatinine level in 40.3% of patients in 9.9 years.