Physical Predictors of Cognitive Performance in Healthy Older Adults:A Cross-Sectional Analysis

<p>There is ample evidence that physical and cognitive performance are related, but the results of studies investigating this relationship show great variability. Both physical performance and cognitive performance are constructs consisting of several subdomains, but it is presently unknown if the relationship between physical and cognitive performance depends on subdomain of either construct and whether gender and age moderate this relationship. The aim of this study is to identify the strongest physical predictors of cognitive performance, to determine the specificity of these predictors for various cognitive subdomains, and to examine gender and age as potential moderators of the relationship between physical and cognitive performance in a sample of community-dwelling older adults. In total, 98 men and 122 women (average age 74.0 +/- 5.6 years) were subjected to a series of performance-based physical fitness and neuropsychological tests. Muscle strength, balance, functional reach, and walking ability (combined score of walking speed and endurance) were considered to predict cognitive performance across several domains (i.e. memory, verbal attention, visual attention, set-shifting, visuo-motor attention, inhibition and intelligence). Results showed that muscle strength was a significant predictor of cognitive performance for men and women. Walking ability and balance were significant predictors of cognitive performance for men, whereas only walking ability was significant for women. We did not find a moderating effect of age, nor did we find support for a differential effect of the physical predictors across different cognitive subdomains. In summary, our results showed a significant relationship between cognitive and physical performance, with a moderating effect of gender.</p>

Specialized edaphic niches of threatened copper endemic plant species in the D.R. Congo: implications for ex situ conservation

Background and aims: Copper (Cu) rich soils derived from rocks of the Katangan Copperbelt in the south-eastern Democratic Republic of Congo (DRC) support a rich diversity of metallophytes including 550 heavy metal tolerant; 24 broad Cu soil endemic; and 33 strict Cu soil endemic plant species. The majority of the plant species occur on prominent Cu hills scattered along the copperbelt. Heavy metal mining on the Katangan Copperbelt has resulted in extensive degradation and destruction of the Cu hill ecosystems. As a result, approximately 80 % of the strict Cu endemic plant species are classified as threatened according to IUCN criteria and represent a conservation priority. Little is known about the soil Cu tolerance optimum of the Cu endemic plant species. The purpose of this study was to quantify the soil Cu concentration (Cu edaphic niche) of four Cu endemic plant species to inform soil propagation conditions and microhabitat site selection for planting of the species in Cu hill ecosystem restoration. Methods: The soil Cu concentration tolerance of Cu endemic plant species was studied including Crotalaria cobalticola (CRCO); Gladiolus ledoctei (GLLE); Diplolophium marthozianum (DIMA); and Triumfetta welwitschii var. rogersii (TRWE-RO). The in situ natural habitat distributions of the Cu endemic plant species with respect to soil Cu concentration (Cu edaphic niche) was calculated by means of a generalised additive model. Additionally, the seedling emergence and growth of the four Cu endemic plant species in three soil Cu concentrations was tested ex situ and the results were compared to that of the natural habitat soil Cu concentration optimum (Cu edaphic niche). Results: CRCO exhibited greater performance on the highest soil Cu concentration, consistent with its calculated Cu edaphic niche occurring at the highest soil Cu concentrations. In contrast, both DIMA and TRWE-RO exhibited greatest performance at the lowest soil Cu concentration, despite the calculated Cu edaphic niche occurring at moderate soil Cu concentrations. GLLE exhibited equal performances in the entire range of soil Cu concentrations. Conclusions: These results suggest that CRCO evolved via the edaphic specialization model where it is most competitive in Cu hill habitat with the highest soil Cu concentration. In comparison, DIMA and TRWE-RO appear to have evolved via the endemism refuge model, which indicates that the species were excluded into (i.e., took refuge in) the lower plant competition Cu hill habitat due to their inability to effectively compete with higher plant competition on normal soils. The soil Cu edaphic niche determined for the four species will be useful in conservation activities including informing soil propagation conditions and microhabitat site selection for planting of the species in Cu hill ecosystem restoration. © 2016 Springer International Publishing Switzerlan