Changes in Cognition and Mortality in Relation to Exercise in Late Life: A Population Based Study

BACKGROUND: On average, cognition declines with age but this average hides considerable variability, including the chance of improvement. Here, we investigate how exercise is associated with cognitive change and mortality in older people and, particularly, whether exercise might paradoxically increase the risk of dementia by allowing people to live longer. METHODS AND PRINCIPAL FINDINGS: In the Canadian Study of Health and Aging (CSHA), of 8403 people who had baseline cognition measured and exercise reported at CSHA-1, 2219 had died and 5376 were re-examined at CSHA-2. We used a parametric Markov chain model to estimate the probabilities of cognitive improvement, decline, and death, adjusted for age and education, from any cognitive state as measured by the Modified Mini-Mental State Examination. High exercisers (at least three times per week, at least as intense as walking, n = 3264) had more frequent stable or improved cognition (42.3%, 95% confidence interval: 40.6-44.0) over 5 years than did low/no exercisers (all other exercisers and non exercisers, n = 4331) (27.8% (95% CI 26.4-29.2)). The difference widened as baseline cognition worsened. The proportion whose cognition declined was higher amongst the high exercisers but was more similar between exercise groups (39.4% (95% CI 37.7-41.1) for high exercisers versus 34.8% (95% CI 33.4-36.2) otherwise). People who did not exercise were also more likely to die (37.5% (95% CI 36.0-39.0) versus 18.3% (95% CI 16.9-19.7)). Even so, exercise conferred its greatest mortality benefit to people with the highest baseline cognition. CONCLUSIONS: Exercise is strongly associated with improving cognition. As the majority of mortality benefit of exercise is at the highest level of cognition, and declines as cognition declines, the net effect of exercise should be to improve cognition at the population level, even with more people living longer

Mediterranean-climate streams and rivers: geographically separated but ecologically comparable freshwater systems

Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers

Thirty years experience with heart valve surgery: isolated aortic valve replacement.

BackgroundThirty years have elapsed since the commencement of open-heart surgery in South Australia. A retrospective study was performed to evaluate mortality and complication rates and to identify factors associated with poor outcomes in all patients who underwent prosthetic aortic valve replacement during this period.MethodsQuestionnaires and personal contact have been used to generate a combined database of pre-operative and post-operative information and long-term follow-up on 1322 patients who underwent isolated prosthetic aortic valve replacement at the Cardio-Thoracic Surgical Unit of the Royal Adelaide Hospital between 1963 and 1992.ResultsComplete survival follow-up data were obtained for 94% (1241) of the patients. The Bjork-Shiley valve was used in 66% (875) of the patients, a Starr-Edwards prosthesis in 31% (412), a St Jude prosthesis in 2% (26), and only 0.7% (9) bioprosthetic valves were inserted. The hospital mortality rate for the 30-year period was 2.9%. Progressively older and less fit patients have undergone surgery in recent years. The long-term survival of patients with aortic stenosis and aortic incompetence was not significantly different. Long-term survival was significantly shorter for patients with higher New York Heart Association (NYHA) functional classifications, and for patients in pre-operative atrial fibrillation. Pre-operative dyspnoea was significantly improved following aortic valve replacement. The rates of postoperative haemorrhagic and embolic complications were low by comparison with other published series.ConclusionsAortic valve replacement can be performed with low hospital mortality and complication rates, and significant symptomatic improvement can be expected. Aortic valve recipients have a favourable prognostic outcome compared with an age- and sex-matched population, and risk factors that determine long-term survival can be identified pre-operatively