Mozley P D, Sadek A M, Alavi A, Gur R C, Muenz L R, Bunow B J, Kim H J, Stecker M H, Jolles P, Newberg A
The University of Pennsylvania, Philadelphia, 19104, USA.
Eur J Nucl Med. 1997 Jul;24(7):754-61. doi: 10.1007/BF00879663.
Some brain functions decline at a linear rate throughout adulthood. Others remain relatively stable until very late in the life cycle. This study characterized the effects of aging on the regional cerebral distribution of hexamethylpropylene amine oxime (HMPAO) in healthy human volunteers. The sample consisted of 26 men and 18 women with a mean age of 41.6+/-14.9 years (range: 19-73). Their past medical histories, physical examinations, and laboratory screening tests were normal. Single-photon emission tomography (SPET) scans of the brain were performed with a standardized acquisition and processing protocol on a triple-headed camera equipped with fan beam collimators. A 3-D restorative filter and a correction for uniform attenuation were applied before the images were reinterpolated in planes parallel to the line connecting the frontal and occipital poles. Mean counts per pixel were measured in multiple regions of interest (ROIs) within each hemisphere by custom fitting a set of templates to the images. The mean activity in each ROI was compared with the mean activity per pixel in the whole brain. Regression analyses were used to relate the activity ratios to age with both linear and nonlinear models. The relative concentration of radioactivity decreased significantly with age in most, but not all, gray matter structures. It increased in the white matter regions. The nonlinear model of aging fit the data significantly better than a straight line did. Most of the changes with age occurred during young adulthood. No further changes were detectable after the onset of middle age. The median breakpoint age at which the rate of change became negligible was 36.6 years. Aging significantly affects the relative uptake of HMPAO in healthy humans. It decreases in many gray matter regions and increases in most white matter regions. However, the changes do not appear to be linear. Most seem to occur during young adulthood before people reach their late thirties. The distribution then appears to remain relatively stable throughout middle age.
在整个成年期，一些脑功能以线性速率衰退。另一些则在生命周期的很晚阶段之前保持相对稳定。本研究描述了衰老对健康人类志愿者脑中六甲基丙烯胺肟（HMPAO）区域脑分布的影响。样本包括26名男性和18名女性，平均年龄为41.6±14.9岁（范围：19 - 73岁）。他们过去的病史、体格检查和实验室筛查测试均正常。使用标准化的采集和处理方案，在配备扇形束准直器的三头相机上对大脑进行单光子发射断层扫描（SPET）。在将图像重新插值到与连接额极和枕极的线平行的平面之前，应用三维恢复滤波器和均匀衰减校正。通过将一组模板自定义拟合到图像，在每个半球的多个感兴趣区域（ROI）中测量每像素的平均计数。将每个ROI中的平均活性与全脑每像素的平均活性进行比较。使用线性和非线性模型进行回归分析，以将活性比率与年龄相关联。在大多数但并非所有灰质结构中，放射性的相对浓度随年龄显著降低。在白质区域中则增加。衰老的非线性模型比直线模型对数据的拟合效果明显更好。大多数随年龄的变化发生在成年早期。中年开始后未检测到进一步变化。变化率变得可忽略不计的中位断点年龄为36.6岁。衰老显著影响健康人体内HMPAO的相对摄取。在许多灰质区域中降低，在大多数白质区域中增加。然而，这些变化似乎不是线性的。大多数变化似乎发生在人们三十多岁后期之前的成年早期。然后在整个中年期，分布似乎保持相对稳定。
