Haltia Lauri T, Viljanen Antti, Parkkola Riitta, Kemppainen Nina, Rinne Juha O, Nuutila Pirjo, Kaasinen Valtteri
Department of Neurology, University of Turku, P.O. Box 52, FIN-20521 Turku, Finland.
J Clin Endocrinol Metab. 2007 Aug;92(8):3278-84. doi: 10.1210/jc.2006-2495. Epub 2007 May 29.
Obesity is associated with several metabolic abnormalities. Recent studies suggest that obesity also affects brain function and is a risk factor for some degenerative brain diseases. The objective of this study was to examine the effects of weight gain and weight loss on brain gray and white matter structure. We hypothesized that possible differences seen in the brains of obese subjects would disappear or diminish after an intensive dieting period.
In part I of the study, we scanned with magnetic resonance imaging 16 lean (mean body mass index, 22 kg/m(2)) and 30 obese (mean body mass index, 33 kg/m(2)) healthy subjects. In part II, 16 obese subjects continued with a very low-calorie diet for 6 wk, after which they were scanned again. Regional brain white and gray matter volumes were calculated using voxel-based morphometry.
White matter volumes were greater in obese subjects, compared with lean subjects in several basal brain regions, and obese individuals showed a positive correlation between white matter volume in basal brain structures and waist to hip ratio. The detected white matter expansion was partially reversed by dieting. Regional gray matter volumes did not differ significantly in obese and lean subjects, and dieting did not affect gray matter.
The precise mechanism for the discovered white matter changes remains unclear, but the present study demonstrates that obesity and dieting are associated with opposite changes in brain structure. It is not excluded that white matter expansion in obesity has a role in the neuropathogenesis of degenerative brain diseases.
肥胖与多种代谢异常相关。近期研究表明，肥胖还会影响脑功能，是一些退行性脑病的危险因素。本研究的目的是探讨体重增加和体重减轻对脑灰质和白质结构的影响。我们假设，在经过一段强化节食期后，肥胖受试者大脑中可能出现的差异会消失或减小。
在研究的第一部分，我们对16名体重正常（平均体重指数，22kg/m²）和30名肥胖（平均体重指数，33kg/m²）的健康受试者进行了磁共振成像扫描。在第二部分，16名肥胖受试者继续进行极低热量饮食6周，之后再次进行扫描。使用基于体素的形态学测量方法计算脑白质和灰质的区域体积。
与体重正常的受试者相比，肥胖受试者在几个脑基底区域的白质体积更大，且肥胖个体脑基底结构的白质体积与腰臀比呈正相关。节食部分逆转了检测到的白质扩张。肥胖和体重正常的受试者之间区域灰质体积无显著差异，节食也未影响灰质。
所发现的白质变化的确切机制尚不清楚，但本研究表明，肥胖和节食与脑结构的相反变化有关。不排除肥胖中的白质扩张在退行性脑病的神经发病机制中起作用。
