Uric acid within the "normal" range predict 9-year cardiovascular mortality in older individuals. The InCHIANTI study.

BACKGROUND AND AIMS: Increased uric acid levels correlate with cardiovascular disease and cardiovascular/overall mortality. To identify a uric acid threshold above which cardiovascular mortality rises, we studied the relationship between uric acid concentration and overall/cardiovascular mortality. METHODS AND RESULTS: We analyzed data from the InCHIANTI study, a cohort study of Italian community-dwelling people with 9 years of follow-up. We selected a sample of 947 individuals over 64 years of age, free from cardio-cerebrovascular disease and with available uric acid measurement at baseline. The sample was divided according to plasma uric acid tertiles. The Hazard ratio (HR) for mortality was calculated by multivariate Cox proportional hazard model. Mean age of participants was 75.3 ± 7.3 years; the mean value of uric acid was 5.1 ± 1.4 mg/dl. Over 9-years of follow-up, 342 (36.1%) participants died, 143 deaths (15.1%) were due to cardiovascular disease. Subjects with higher uric acid concentrations presented a higher cardiovascular mortality [II (4.6-5.5 mg/dl) vs I (1.8-4.5 mg/dl) tertile HR: 1.98, 95%C.I. 1.22-3.23; III (≥5.6 mg/dl) vs I tertile HR: 1.87, 95%C.I. 1.13-3.09]. We found a non-linear association between uric acid concentrations and cardiovascular mortality with the lowest mortality for values of about 4.1 mg/dl and a significant risk increment for values above 4.3 mg/dl. CONCLUSION: In community-dwelling older individuals free from cardio-cerebrovascular events, the lowest 9-year cardiovascular mortality was observed for uric acid values far below current target values. If confirmed, these data might represent the background for investigating the efficacy of uric acid levels reduction in similar populations.

Computerized cognitive training and brain derived neurotrophic factor during bed rest: mechanisms to protect individual during acute stress.

Acute stress, as bed rest, was shown to increase plasma level of the neurotrophin brain-derived neurotrophic factor (BDNF) in older, but not in young adults. This increase might represent a protective mechanism towards acute insults in aging subjects. Since computerized cognitive training (CCT) is known to protect brain, herein we evaluated the effect of CCT during bed rest on BDNF, muscle mass, neuromuscular function and metabolic parameters. The subjects that underwent CCT did not show an increase of BDNF after bed rest, and showed an anti-insular modification pattern in metabolism. Neuromuscular function parameters, already shown to beneficiate from CCT, negatively correlated with BDNF in research participants undergoing CCT, while positively correlated in the control group. In conclusion, BDNF increase can be interpreted as a standardized protective mechanism taking place whenever an insult occurs; it gives low, but consistent preservation of neuromuscular function. CCT, acting as an external protective mechanism, seems to modify this standardized response, avoiding BDNF increase or possibly modifying its time course. Our results suggest the possibility of differential neuroprotective mechanisms among ill and healthy individuals, and the importance of timing in determining the effects of protective mechanisms.

Brain-derived neurotrophic factor plasma levels: relationship with dementia and diabetes in the elderly population.

The mechanisms linking diabetes and cognitive impairment/dementia, two common conditions of elderly people, are not completely known. Brain-derived neurotrophic factor (BDNF) has antidiabetic properties, and reduced circulating BDNF was associated with dementia. We investigated the relationship between plasma BDNF levels, dementia, and diabetes in a sample of 164 community-dwelling elderly individuals, including 50 participants with vascular dementia, 44 with late onset Alzheimer's disease, 23 with cerebrovascular disease not dementia, and 47 controls (C). Presence/absence of diabetes was registered; new diagnoses of diabetes were made by the American Diabetes Association criteria. BDNF plasma levels were measured by ELISA. Both diagnosis of dementia and diabetes were associated with lower BDNF plasma values compared with the respective controls; moreover, dementia and diabetes correlated with BDNF plasma levels, independent of possible confounders. A progressive reductions of BDNF plasma levels from C (383.9 ± 204.6 pg/mL), to cerebrovascular disease not dementia (377.1 ± 130.2), to vascular dementia (313.3 ± 114.8), to late onset Alzheimer's disease (264.7 ± 147.7) was observed, (late onset Alzheimer's disease vs C, p: .03; late onset Alzheimer's disease vs cerebrovascular disease not dementia, p: .002). Demented patients affected by diabetes had the lowest BDNF mean levels (264.9 pg/mL) among individuals enrolled in this sample, suggesting the existence of a "synergistic" effect of dementia and diabetes on BDNF levels.