Gazdzinski Stefan, Kornak John, Weiner Michael W, Meyerhoff Dieter J
Center for Imaging of Neurodegenerative Diseases, San Francisco Veterans Administration Medical Center, University of California San Francisco, San Francisco, CA 94121, USA.
Ann Neurol. 2008 May;63(5):652-7. doi: 10.1002/ana.21377.
Obesity and being overweight during adulthood have been consistently linked to increased risk for development of dementia later in life, especially Alzheimer's disease. They have also been associated with cognitive dysfunction and brain structural alterations in otherwise healthy adults. Although proton magnetic resonance spectroscopy may distinguish between neuronal and glial components of the brain and may point to neurobiological mechanisms underlying brain atrophy and cognitive changes, no spectroscopic studies have yet assessed the relationships between adiposity and brain metabolites.
We have utilized magnetic resonance imaging and proton magnetic resonance spectroscopic imaging data from 50 healthy middle-aged participants (mean age, 41.7 +/- 8.5 years; 17 women), who were scanned as control subjects for another study.
After adjustment for age and sex, greater body mass indices (BMIs) correlated with: (1) lower concentrations of N-acetylaspartate (spectroscopic marker of neuronal viability) in frontal (p = 0.001), parietal (p = 0.006), and temporal (p = 0.008) white matter; (2) lower N-acetylaspartate in frontal gray matter (p = 0.01); and (3) lower concentrations of choline-containing metabolites (associated with membrane metabolism) in frontal white matter (p = 0.05).
These results suggest that increased BMI at midlife is associated with neuronal and/or myelin abnormalities, primarily in the frontal lobe. Because white matter in the frontal lobes is more prone to the effects of aging than in other lobes, our results may reflect accelerated aging in individuals with high levels of adiposity. Thus, greater BMI may increase the odds of developing an age-related disease, such as Alzheimer's disease.
成年期肥胖和超重一直与晚年患痴呆症尤其是阿尔茨海默病的风险增加有关。它们还与原本健康的成年人的认知功能障碍和脑结构改变有关。尽管质子磁共振波谱可以区分大脑的神经元和胶质细胞成分，并可能指出脑萎缩和认知变化背后的神经生物学机制，但尚无波谱研究评估肥胖与脑代谢物之间的关系。
我们利用了来自50名健康中年参与者（平均年龄41.7±8.5岁；17名女性）的磁共振成像和质子磁共振波谱成像数据，这些参与者是作为另一项研究的对照对象接受扫描的。
在对年龄和性别进行校正后，较高的体重指数（BMI）与以下情况相关：（1）额叶（p = 0.001）、顶叶（p = 0.006）和颞叶（p = 0.008）白质中N-乙酰天门冬氨酸（神经元活力的波谱标志物）浓度较低；（2）额叶灰质中N-乙酰天门冬氨酸较低（p = 0.01）；（3）额叶白质中含胆碱代谢物（与膜代谢相关）浓度较低（p = 0.05）。
这些结果表明，中年时BMI升高与神经元和/或髓鞘异常有关，主要发生在额叶。由于额叶白质比其他脑叶更容易受到衰老的影响，我们的结果可能反映了肥胖个体的加速衰老。因此，较高的BMI可能会增加患与年龄相关疾病如阿尔茨海默病的几率。
