Brain white matter expansion in human obesity and the recovering effect of dieting.

CONTEXT AND OBJECTIVE 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

[1]  Kristine Yaffe,et al.  Obesity in middle age and future risk of dementia: a 27 year longitudinal population based study , 2005, BMJ : British Medical Journal.

[2]  Deborah Gustafson,et al.  An 18-year follow-up of overweight and risk of Alzheimer disease. , 2003, Archives of internal medicine.

[3]  J T Kuikka,et al.  Regional cerebral blood flow during food exposure in obese and normal-weight women. , 1997, Brain : a journal of neurology.

[4]  Karl J. Friston,et al.  Voxel-Based Morphometry—The Methods , 2000, NeuroImage.

[5]  C. Bouchard,et al.  Role of Deep Abdominal Fat in the Association Between Regional Adipose Tissue Distribution and Glucose Tolerance in Obese Women , 1989, Diabetes.

[6]  W. Heindel,et al.  Dehydration confounds the assessment of brain atrophy , 2005, Neurology.

[7]  E M Reiman,et al.  Effect of satiation on brain activity in obese and lean women. , 2001, Obesity research.

[8]  R. Levy,et al.  Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. , 1972, Clinical chemistry.

[9]  Karl J. Friston,et al.  A Voxel-Based Morphometric Study of Ageing in 465 Normal Adult Human Brains , 2001, NeuroImage.

[10]  C M Burchfiel,et al.  Metabolic Cardiovascular Syndrome and Risk of Dementia in Japanese-American Elderly Men: The Honolulu-Asia Aging Study , 2000, Arteriosclerosis, thrombosis, and vascular biology.

[11]  P T Fox,et al.  Altered hypothalamic function in response to glucose ingestion in obese humans. , 1999, Diabetes.

[12]  R M Peshock,et al.  Prediction of total subcutaneous abdominal, intraperitoneal, and retroperitoneal adipose tissue masses in men by a single axial magnetic resonance imaging slice. , 1997, The American journal of clinical nutrition.

[13]  T. Wadden,et al.  Short- and long-term changes in serum leptin dieting obese women: effects of caloric restriction and weight loss. , 1998, The Journal of clinical endocrinology and metabolism.

[14]  E M Reiman,et al.  Differential brain responses to satiation in obese and lean men. , 2000, Diabetes.

[15]  F. Azizi,et al.  Is there an independent association between waist-to-hip ratio and cardiovascular risk factors in overweight and obese women? , 2004, International journal of cardiology.

[16]  G. Winocur,et al.  High-fat diets, insulin resistance and declining cognitive function , 2005, Neurobiology of Aging.

[17]  A. Pocai,et al.  Restoration of hypothalamic lipid sensing normalizes energy and glucose homeostasis in overfed rats. , 2006, The Journal of clinical investigation.

[18]  Stanley I. Rapoport,et al.  In vivo fatty acid incorporation into brain phosholipids in relation to plasma availability, signal transduction and membrane remodeling , 2001, Journal of Molecular Neuroscience.

[19]  Jean Logan,et al.  Brain dopamine and obesity , 2001, The Lancet.

[20]  B Lees,et al.  Body fat distribution, rather than overall adiposity, influences serum lipids and lipoproteins in healthy men independently of age. , 1995, The American journal of medicine.

[21]  M. Jensen,et al.  Treatment of obesity with diet/exercise versus pioglitazone has distinct effects on lipoprotein particle size. , 2006, Atherosclerosis.

[22]  R. Ross,et al.  Separate Associations Between Visceral and Subcutaneous Adipose Tissue Distribution, Insulin and Glucose Levels in Obese Women , 1996, Diabetes Care.

[23]  Miguel A Hernán,et al.  Obesity and the risk of Parkinson's disease. , 2004, American journal of epidemiology.

[24]  Mohammad Sharafi,et al.  Responsivity to food stimuli in obese and lean binge eaters using functional MRI , 2006, Appetite.

[25]  Kewei Chen,et al.  Brain abnormalities in human obesity: A voxel-based morphometric study , 2006, NeuroImage.

[26]  G. Berglund,et al.  Sex differences in the relationships between BMI, WHR and incidence of cardiovascular disease: a population-based cohort study , 2006, International Journal of Obesity.