Search

Apolipoprotein-E4 ( APOE -E4) is a major genetic risk factor for developing Alzheimer's disease (AD). The verbal fluency task (VFT), especially the subtask category fluency, has shown to provide a good discrimination between cognitively normal controls and subjects with AD. Interestingly, APOE -E4 seems to have no effect on the behavioral performance during a VFT in healthy elderly. Thus, the purpose of the present study was to reveal possible compensation mechanisms by investigating the effect of APOE -E4 on the hemodynamic response in non-demented elderly during a VFT by using functional near-infrared spectroscopy (fNIRS). We compared performance and hemodynamic response of high risk APOE -E4/E4, -E3/E4 carriers with neutral APOE -E3/E3 non-demented subjects ( N = 288; 70-77 years). No difference in performance was found. APOE -E4/E4, -E3/E4 carriers had a decreased hemodynamic response in the right inferior frontal junction (IFJ) with a corresponding higher response in the left middle frontal gyrus (MFG) during category fluency. Performance was correlated with the hemodynamic response in the MFG. We assume a compensation of decreased IFJ brain activation by utilizing the MFG during category fluency and thus resulting in no behavioral differences between APOE -groups during the performance of a VFT.

In Alzheimer's disease (AD), the degeneration of brainstem nuclei is different from major depression (MD). Thus, vagus somatosensory evoked potentials (VSEP) proposed for the functional assessment of brainstem nuclei should show prolonged latencies in AD but not in MD. In 55 AD patients, 57 MD patients and two age-matched control groups evoked potentials were recorded upon stimulation of the auricular branch of the vagus nerve. In the AD, not in the MD group, latencies were significantly longer as compared to controls. Thus, the method of VSEP could contribute to the important differential diagnosis of AD and MD in elderly patients.

The trail making test (TMT) is a widely applied diagnostic tool measuring executive functioning in order to discriminate between healthy and pathological aging processes. However, due to its paper-and-pencil nature it is difficult to adapt for functional brain imaging. Related neural underpinnings even in healthy aging are mostly unknown since no consistent administration for imaging is available. In this study a standardized implementation of the TMT for functional near-infrared spectroscopy (fNIRS) is proposed to investigate associated frontal cortex activation in healthy young (mean age 25.7 ± 3.02 years) and elderly adults (mean age 70.95 ± 3.55 years). The TMT consisted of a number condition (TMT-A), an alternating number and letter condition (TMT-B) as well as a control task. Behavioral results demonstrated that elderly participants performed slower but committed a similar number of errors compared to younger adults. The fNIRS results showed that particularly the TMT-B provoked bilateral activation in the ventro- and dorsolateral prefrontal cortex (vlPFC and dlPFC) as well as in premotor regions. Elderly participants displayed more significantly activated channels and a different activation pattern compared to younger participants especially manifesting in more bilateral dlPFC activation. In line with the hemispheric asymmetry reduction in elderly adults (HAROLD) model, the results were interpreted as an additional need for cognitive control resources in elderly participants. This study succeeded in implementing an appropriate version of the TMT for fNIRS and helps elucidating neural aging effects associated with this task., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Objective: Visuospatial deficits are among the first symptoms of Alzheimer disease (AD) and linked to lower activation in the superior parietal cortex as assessed with functional imaging. Near-infrared spectroscopy (NIRS) is an optical method to measure changes in the concentration of oxygenated hemoglobin and deoxygenated hemoglobin in the microvascular system of the cortex. Because of its advantages in measurement situation, NIRS has proven to be especially suited for investigating psychiatric patients. The aim of this study was to probe the activation of parietal regions in patients with AD, performing a visuospatial task by means of functional NIRS (fNIRS)., Methods: Thirteen patients with suspected mild AD and 13 healthy subjects comparable in age and gender were investigated while working on a modified version of the Benton Line Orientation Task., Results: During the spatial task, healthy subjects showed explicit parietal activation, whereas patients displayed only activation during the control task. Interestingly, there was no difference in visuospatial performance between the two groups., Conclusion: The results indicate that fNIRS is able to measure parietal activation deficits in patients with AD, which could be developed into an early detection method in the future.

Objective: Quantitative ultrasound of the calcaneus is used clinically for evaluating bone fracture risk, but its association with the mechanical properties at other skeletal sites is not well characterized. The objective was therefore to determine its predictive ability of the mechanical failure loads of the proximal femur and lumbar spine., Method: In 45 human cadavers (29 males and 16 females, aged 82.5 +/- 9.6 years), we determined the speed of sound, broadband ultrasonic attenuation (BUA) and the empirical stiffness index, using a commercial quantitative ultrasound scanner. The proximal femora and the fourth vertebral body were excised and loaded to failure in a testing machine., Results: Femoral failure loads ranged from 933 to 7000 N and those of the vertebrae from 1000 to 7867 N, their correlation being 0.51 in females and -0.08 in males. Forty percent of the variability of femoral, but only 24% of the variability of the vertebral fracture loads could be predicted with calcaneal speed of sound. In the femur, a combination of speed of sound and BUA improved the prediction (r2 = 50-60%), but not in the spine., Conclusions: The study provides experimental evidence that calcaneal quantitative ultrasound is capable of predicting mechanical failure at other skeletal sites and has potential to identify patients at risk from osteoporotic fracture. The different association of quantitative ultrasound with femoral and vertebral failure may result from the influence of the cortical bone and a higher microstructure-related similarity of the calcaneus and the femur.

The objective of the current study was to determine the correlation of spinal and femoral dual-energy X-ray absorptiometry (DXA) and calcaneal ultrasound, measured in situ with intact soft tissues, with the in vitro failure loads of lumbar vertebral bodies. Forty-nine cadavers with intact skin and soft tissues (32 men aged 82.1 +/- 9.0 years, 17 women aged 83.1 +/- 10.1 years) were examined. The bone mineral content (BMC), the projectional area, and the bone mineral density (BMD) of the lumbar spine and proximal femur were determined with DXA, and the ultrasonic properties of the calcaneus with quantitative calcaneal ultrasound. The fourth lumbar vertebra was then excised with adjacent intervertebral disks and its mechanical failure load determined, using a materials testing machine. Absolute fracture loads were significantly higher in men than in women, but they were similar after adjusting for body weight and height. Spinal DXA was significantly associated with vertebral failure load (r = 0.62 combined; r = 0.54 men; r = 0.58 women). Femoral DXA (r = 0.46) and calcaneal ultrasound (r = 0.48) showed somewhat lower correlation coefficients, with the speed of sound (SOS) being able to add predictive information in a stepwise regression model. Normalizing the vertebral failure loads to body weight and height reduced the correlations, with only spinal DXA yielding a significant relationship. Our data suggest that previous in vitro studies may have overestimated the association between spinal DXA and vertebral failure loads, presumably because measurements were performed on excised bones, but not in situ in the presence of soft tissue inhomogeneity. The results indicate that, even in a population of old age and under in situ conditions, spinal DXA may still be somewhat better than femoral DXA and calcaneal ultrasound in predicting vertebral failure loads.

The objective of this study was to determine experimentally the sex-specific correlation of femoral and lumbar DXA and calcaneal ultrasound, measured in situ, with the in vitro failure loads of the proximal femur. Fifty-eight cadavers with intact skin and soft tissues (34 male, aged 81.2 +/- 8.7 years; 24 female, aged 83.7 +/- 10.6 years) were examined. The bone mass of the proximal femur and the lumbar spine were determined using dual-energy X-ray absorptiometry and the ultrasonic properties of the calcaneus with quantitative ultrasound. Afterwards, the right femora were excised 18 cm distal to the minor trochanter, and their load to failure determined with a material testing machine. Femoral fracture loads were significantly higher in males than in females, both before and after correcting for body height and weight. Femoral neck bone mineral density (BMD) was significantly correlated with femoral failure loads (r = 0.65 all specimens, 0.57 males (0.64 after excluding trochanteric fractures) and 0.77 females; p < 0.001). The correlations with the ultrasonic Stiffness Index of the calcaneus were in a similar range (r = 0.67 all specimens, 0.48 males (0.64 after excluding trochanteric fractures) and 0.65 females; p < 0.001). The correlations between femoral failure loads and the spinal BMD were lower (r = 0.40, p < 0.01), particularly in males (r = 0.30, not significant). In contrast to previous experimental investigations on excised bones, our results are consistent with clinical studies that have reported that ultrasound and femoral DXA have a similar ability to predict the risk of hip fracture.