Muscle strength, postural balance, and cognition are associated with braking time during driving in older adults.

BACKGROUND: Despite the well-known declines in driving performance with advancing age, there is little understanding of the specific factors that predict changes in key determinants such as braking time. OBJECTIVES: The aims of this study were to determine the extent to which age, muscle strength, cognition and postural balance are associated with braking performance in middle-aged and older adults. METHODS: Male and female middle-aged adults (n=62, age=39.3±7.1years) and older adults (n=102, age=70.4±5.8years) were evaluated for braking performance, as well as in several motor and cognitive performance tasks. The motor evaluation included isokinetic ankle plantar flexor muscle strength, handgrip strength, and postural balance with and without a cognitive task. The cognitive assessment included the Mini Mental State Examination. Braking performance was measured using a driving simulator. RESULTS: Older adults exhibited 17% slower braking time, lower strength, and poorer performance in the postural balance (p<0.001). For both older and middle-aged adults, significant correlates of braking time included performance in the postural balance tests, muscle strength, and cognitive function. However, after full model adjustment, only postural balance and cognitive function were significantly associated. CONCLUSION: Muscle strength, postural balance, and cognition are associated with braking time, and may affect the safety of and driving performance in older adults. These findings may help to inform specific targeted interventions that could preserve driving performance during aging.

Pro198Leu polymorphism affects the selenium status and GPx activity in response to Brazil nut intake.

Selenoproteins play important roles in antioxidant mechanisms, and are thus hypothesised to have some involvement in the pathology of certain types of dementia. Mild cognitive impairment (MCI) and Alzheimer's disease (AD) are both thought to involve impaired biological activity of certain selenoproteins. Previously, supplementation with a selenium-rich Brazil nut (Bertholletia excelsa) has shown potential in reducing cognitive decline in MCI patients, and could prove to be a safe and effective nutritional approach early in the disease process to slow decline. Here, we have conducted a pilot study that examined the effects of a range of single nucleotide polymorphisms (SNPs) in genes encoding the selenoproteins glutathione peroxidase (GPX1) and selenoprotein P (SEPP) in response to selenium supplementation via dietary Brazil nuts, including selenium status, oxidative stress parameters and GPX1 and SEPP gene expression. Our data suggest that GPX1 Pro198Leu rs1050450 genotypes may differentially affect the selenium status and GPx activity. Moreover, rs7579 and rs3877899 SNPs in SEPP gene, as well as GPX1 rs1050450 genotypes can influence the expression of GPX1 and SEPP mRNA in response to Brazil nuts intake. This small study gives cause for larger investigations into the role of these SNPs in both the selenium status and response to selenium dietary intake, especially in chronic degenerative conditions like MCI and AD.