This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Haltia, L. T. Articles by Kaasinen, V. Search for Related Content PubMed PubMed Citation Articles by Haltia, L. T. Articles by Kaasinen, V. Related Collections Neuroendocrinology and Pituitary Obesity

Brain White Matter Expansion in Human Obesity and the Recovering Effect of Dieting

Departments of Neurology (L.T.H., N.K., V.K.), Internal Medicine (A.V., P.N.), and Radiology (R.P.), University of Turku, FIN-20521 Turku, Finland; and Turku PET Centre (L.T.H., A.V., N.K., J.O.R., P.N., V.K.), FIN-20521 Turku, Finland

Address all correspondence and requests for reprints to: Dr. Lauri T. Haltia, Turku PET Centre, University of Turku, P.O. Box 52, FIN-20521 Turku, Finland. E-mail: toivo.haltia{at}tyks.fi.

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/m²) and 30 obese (mean body mass index, 33 kg/m²) 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.