Poor physical performance and dementia in the oldest old: the 90+ study.

OBJECTIVE: To examine the cross-sectional relationship between physical performance and dementia in the oldest old (those ≥ 90 years of age). DESIGN: Cross-sectional study. SETTING: The 90+ Study is a population-based, longitudinal, epidemiologic study of aging and dementia performed at the University of California, Irvine, from January 1, 2003, through November 30, 2009. PARTICIPANTS: A total of 629 participants from The 90+ Study were included in the study. The mean age was 94 years, and most (72.5%) were women. MAIN OUTCOME MEASURES: All-cause dementia, based on Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria, was the main outcome measure. The independent variables were physical performance measures, including 4-m walk, 5 chair stands, standing balance, and grip strength, each scored from 0 to 4 (0, unable to perform; 4, best performance). Odds of dementia in relation to the physical performance measures were estimated by logistic regression after adjustment for age and sex. RESULTS Poor physical performance in all measures was significantly associated with increased odds of dementia (P< .001). Odds ratios for every unit decrease in physical performance score were 2.1 for 4-m walk, 2.1 for chair stands, 1.9 for standing balance, and 1.7 for grip strength. CONCLUSIONS: We found a strong cross-sectional relationship between poor physical performance and dementia in people 90 years and older. Our findings suggest that dementia is a complex neurodegenerative process that may affect physical performance and cognition. Additional research is necessary to determine the temporal relationship between poor physical performance and cognitive dysfunction.

Reproducibility of quantitative tractography methods applied to cerebral white matter.

Tractography based on diffusion tensor imaging (DTI) allows visualization of white matter tracts. In this study, protocols to reconstruct eleven major white matter tracts are described. The protocols were refined by several iterations of intra- and inter-rater measurements and identification of sources of variability. Reproducibility of the established protocols was then tested by raters who did not have previous experience in tractography. The protocols were applied to a DTI database of adult normal subjects to study size, fractional anisotropy (FA), and T2 of individual white matter tracts. Distinctive features in FA and T2 were found for the corticospinal tract and callosal fibers. Hemispheric asymmetry was observed for the size of white matter tracts projecting to the temporal lobe. This protocol provides guidelines for reproducible DTI-based tract-specific quantification.