| Author, country | Study population | Assessment | Main findings | N; age: mean (SD) years; BMI: mean (SD) (kg/m2) |
| Herrmann et al. [72],Germany | Meta-analysis of 10 studies [73-82] | MRI studies | Obese status: ↓ GMV: B IFG (including insula), L MFG, L preFC, L MTG, L PCG, L cerebellum, BA 34 (including L amygdala and L lenticular nucleus) | Voxel-wise meta-analysis: GMV | BMI |
| Taki et al. [83], Japan | N = 1,428 Men = 690, A: 44.5 (16.1) Women = 738, A: 46.4 (14.1) | MRI: VBM: GMV, GMr | Men: ↑ BMI, ↓ GMV: B uncus, B cerebellum (anterior lobe), L FG, R SPL, R preCG, R IFG, B precuneus, B SFG, R midbrain | BMI | ↑ BMI, ↑ GMV: B IFG, B cerebellum (posterior lobe), R SFG, R STG, R ITG, L MTG, B Th (pulvinar), R CG, B Cn (heads), L preCG | No significant correlations in women |
| García-García et al. [86], Canada | Meta-analysis of 21 studies (including 73, 76-80, 82-83, 85, 88, 115) N = 5,882 | MRI studies: VBM analyses: GMV | Obesity-related variables are associated with ↓ GMV mainly in mPFC, B cerebellum, L TPole | Obesity-related variables (BMI, WC, WHR, BFD) | Less robust results: preCG, IPC |
| Yokum et al. [87], USA | N = 83 (women), A: 18.4 (2.8) BMI range: 17.3–38.9 | MRI: VBM: | Total GMV: obese < OW, lean | WMV and GMV | Overall WMV: obese < OW | BMI | ↑ BMI, ↑ GMV: MOG | ↑ BMI, ↑ WMV: MTG, FG, PHipG, RO, DS | One-year follow-up: ↑ BMI, ↓ GMV: SFG, MF |
| Papageorgiou et al. [89], Greece | N = 268, A: 46.3 (16.1) Obese = 52 OW = 96 Normal weight = 120 | MRI: DTI: brain fractional anisotropy | ↑ BMI was related with ↓ ATR, PTR, IFOF, ILF, SLF, CC, UF, IC, CST, cingulum | WM | BMI |
| Repple et al. [90], Germany | N = 1,433 Münster Neuroimaging Cohort = 369 Human Connectome Project = 1064 | MRI: DTI: brain fractional anisotropy, WM | ↑ BMI globally, ↓ WM integrity (replication in an independent sample) | BMI |
| Kullman et al. [91], Germany/UK | N = 48 | MRI: DTI, voxel-based quantification analysis | ↑ BMI, ↓ predominantly in the SLF, ATR, IC, and CC | Obese = 12, A: 26.9 (4.5), BMI: 33.2 (3.2) | WM | OW = 12, A: 26.1 (2), BMI: 28.1 (1.4) | BMI | Lean = 24, A: 26.7 (3.7), BMI: 22.4 (1.6) |
| Kim et al. [92], South Korea | N = 54 Obese = 27, A: 23.15 (3.2), BMI: 30.12 (3.8); lean = 27, A: 26.1 (5.78), BMI: 21.76 (1.7) | MRI: vertex-based and shape analysis | ↑ BMI, ↓ B Cn | Subcortical structures volume | ↑ BMI, ↑ B Th, B Pu, B GP, B hip | BMI |
| Raji et al. [93], USA | N = 94 | MRI: tensor-based morphometry | Globally: ↑ BMI, ↓ GMV and WMV | Obese = 14, A: 76.9 (2.8), BMI: 32.9 (2.5) | BMI, FPI, T2DM | ↑ BMI, ↓ V: OFC, hip, Pu, GP, Th | OW = 51, A: 77.2 (2.6), BMI: 27.5 (1.4) | ↑ FPI, ↓ V: splenium CC, OFC, hip | Lean = 29, A:77.5 (4), BMI: 22.5 (1.9) | ↑ T2DM, ↓ V: genu and splenium CC, ACC, mTL, OL, Cn, Pu, GP |
| Dekkers et al. [94], Netherlands | N = 12,087 (from UK Biobank study) | MRI: multiparametric brain mapping; DTI | In women: ↑ TBF, ↑ GMV, WMV; ↓ GP | TBF | In men: ↑ TBF, ↓ GMV, Th, Cn, Pu, GP, hip, Nac |
| Le et al. [96], USA/Taiwan | N = 105 (58 women), A: 31.4 (12.6) | MRI: VBM and rsFC analyses Hypothalamic GMV | ↑ BMI, ↑ hypothalamic GMV, and ↑ connectivity with the insula, Th, GP, and cerebellum but ↓ with hypothalamic connectivity with the SPL | BMI: 25.8 (4.7) | BMI |
| Ou et al. [97], USA | N = 24 | MRI: VBM and TBSS analyses: GMV, WMV | Obese: ↓ GMV: R MTG, B Th, L SPL, L preCG, postCG, L cerebellum | Obese = 12, A: 9.1 (0.9), BMI: 24.4 (3.4) | BMI | Obese: ↑ WMV: B posterior IFOF, B posterior SFOF, B SCR | Lean = 12, A: 9.8 (0.7), BMI: 15.8 (1) |
| Perlaki et al. [98], Hungary/Netherlands/ Germany/Sweden | N = 51, (32 female), A: 13.8 (1.9) | MRI: VBM: GMV, GMM | VBM analysis controlled for age, sex, and ICV; no significant associations between GMM and BMI z-score | ROIs | ROI: ↑ BMI z-score, ↑ B amygdala, ↑ Nac | BMI z-score |
| Sharkey et al. [100], Canada | N = 378 (from NIH Pediatric MRI Data Repository); age range: 4–18 | MRI: cortical thickness | No significant correlations were found between cortical thickness and BMI z-score using FDR multiple comparison correction | ROIs | BMI z-score |
| Yokum and Stice [101], USA [72] | N = 162, (81 female), A: 15.3 (1.1) | MRI: VBM: GMV, WMV | BF gain < BF loss: Pu | N = 60 completed a second scan at two- or three-year follow-up. | BMI: BF gain, BF stability, BF loss | BF gain > BF loss: dorsal/subgenual ACC | BF gain > BF stability: subgenual ACC |
| Marqués-Iturria et al. [103], Spain | N = 39 | MRI: ICV, TGM, CGM, sub-CGM, WMV, mean surface, mean thickness | ↑ BMI, ↓ L CGM: SFG, MFG (caudal), ACC (rostral and caudal), preCG | Obesity = 19, A: 33.7 (5.7), BMI: 36.1 (5.9) | BMI | ↑ BMI, ↓ R CGM: mOFC, SFG, MFG (rostral), FPole, OFC | Lean = 18, A: 32.3 (5.9), BMI: 22.54 (1.94) | ↑ BMI, ↓ V: L vDC, R vDC, brainstem |
| Ottino-González et al. [104], Spain/Canada | N = 63 | MRI | Overweight: ↑ AL index, ↓ cortical thickness Lean: ↑ AL index, ↑ cortical thickness in pars triangularis, L medial SFG, supramarginal gyrus, IPC, precuneus | OW-obese = 34, A: 31.8 (6.1), BMI: 31.4 (5) | Cortical thickness | Lean = 29, A: 30.07 (6.2), BMI: 22.35 (1.82) | BMI, WC | AL index (15 biomarkers) |
| Shan et al. [105], China | N = 76 | MRI: GMV | ↑ Creatinine, ↑ GMV ↑ HbA1c, LDL, triglyceride, ↓ GMV | Obese = 37, A: 27.8 (6.9), BMI: 40 (6.5) | BMI, DBP, creatinine; FBS, HbA1c; HDL, LDL; SBP, SUA, triglyceride | Lean = 39, A: 26.7 (6.8), BMI: 21.8 (1.8) | Obese < lean | R SPG, SOG, AG, cerebellum |
| Beyer et al. [106], Germany | N = 748, A: 68.4 (4.8) | MRI: VBM: GMV, ICV | Metabolic profile (↑ BMI, WHR, HbA1c, leptin, CRP, ↓ adiponectin) associated with ↓ GMV | BMI: 27.7 (4.1) | BMI, WHR, metabolic profile (adiponectin, CRP, HbA1c, HDL, IL-6, SBP, TC) | Th, B insular Cx, L amygdala-hip, TPole, cerebellum |
| Kotkowski et al. [107], USA | N = 208 | MRI: VBM: GMV | Metabolic syndrome was associated with ↓ GMV | MetS = 104, A: 37.3 (13.2), BMI: 34.5 (5.5) | Cerebellum, OFC, R insula, cuneus, B Cn (body), R TL, R amygdala, BA34. | Controls = 104, 37.3 (13.2), BMI: 24.3 (3.8) | MetS |
| Climie et al. [108], Australia | N = 560 | MRI: VBM: GMV, hip volume | T2DM is associated with ↓ GMV, ↓ hip volume, ↑ WHR, BMI, ↓ physical activity | T2DM = 258, A: 67 (7) | WHR, BMI, physical activity (steps/day), and blood biochemistry | T2DM-GMV association is mediated by WHR | Non-T2DM = 302, A: 72 (7) |
| Nouwen et al. [109], UK | N = 53 | MRI: VBM, TBSS: GMV, WMV, T2DM, obesity GMV: control > T2DM: B Cn, B Pu | Control > obese: R hip, R amygdala-hip, L amygdala, L Pu | T2DM = 14, A: 16.1 (1.5) | Control > T2DM + obese: R Pu/Cn, L Cn, L Pu, L Th/Cn, L hip/amygdala | Obesity = 20, A: 14.9 (2) | WM: T2DM < controls: L CST, mCC, L fornix, L ThR, L RLIC, L IFOF, R ACR, CC (genu), L uncinate, cingulum |
| Bernardes et al. [110], Brazil/ Netherlands | N = 75 | MRI: CT, surface area, GMV | CT: obese + T2DM < controls, obese (normoglycemic) < controls: R insula | Obese + T2DM = 28, A: 60.4 (5) | T2DM, adiposity, glucose, and insulin | Surface area: obese + T2DM < controls: L lateral occipital | Obese (normoglycemic) = 16, A: 58 (8.4) | Surface area, GMV: Th, obese + T2DM < obese (normoglycemic): L paracentral | Control = 31, A: 57 (7.1) |
| Rofey et al. [111], USA | N = 15 | MRI: GMV | GMV, WM integrity: Cn, Th | T2DM = 5, A: 18 (1.4) | BMI, T2DM | T2DM < obese < lean: Cn | Obese (without T2DM) = 5, A: 15.4 (2.2) | T2DM < obese; T2DM < lean: Th | Lean = 5, A: 14.5 (2.5) |
| Redel et al. [112], USA | N = 40 | MRI: VBM: GMV, voxel-wise GM, WMV | Global GMV: obese + T2DM < control | T2DM = 20, A: 16.7 (2.6), BMI: 37.8 (4.7) | BMI, T2DM | Regional GMV: Obese + T2DM < control: R mTL, L fusiform, L IPG, R cerebellum, B ITG, R cingulum, R MOG, R IOG, L Cn, L angular, R lingual | Control = 20, A: 16.7 (2), BMI: 24.5 (5.2) | Obese + T2DM > control: B Pu, R ITG, R Th, B paracentral |
| Yoon et al. [113], South Korea | N = 150 | MRI: GMV, CT | Global mean CT: T2DM + OW and T2DM < control | T2DM + OW = 50, A: 49 (7.4), BMI: 28.1 (2) | T2DM, BMI | Regional CT: T2DM + OW and T2DM < control: B FG, L ITG, B STG, B SFG, L MFG, B IFC, L insula, B lingual Cx, R OFC | T2DM = 50, A: 49.3 (8.1), BMI: 22.8 (2) | WM: T2DM + OW and T2DM < control: Fornix, CC, CST, IFOF, ATR | Control = 50, A: 49 (7.8), BMI: 22.7 (1.8) | Duration-related alteration in CT: T2DM + OW > T2DM |
| Caunca et al. [114], USA/Japan | N = 1,289 (from the Northern Manhattan MRI Substudy), A: 64 (8) | MRI: ICV, mean CT, WMHV | ↑ BMI and ↑ WC z-score, ↓ mean CT | Obese < normal: CT | BMI z-score, WHR z-score, WC z-score, adiponectin | No association between obesity and cerebral small vessel disease (WMHV) |
| Hayakawa et al. [116], Japan | N = 792 | MRI: voxel-wise analyses | Men: ↑ WC, BMI, ↓ GMV: B ITG, R MTG, L fusiform, L Th, L red nucleus, L mFG, R SFG, R IFG, R preCG, R postCG, B cerebellum | Men = 523, A: 55.3 (9.7) | GMV; GMr, ICV | Women: ↑ WC, BMI, ↓ GMV: B Th, R red nucleus, L preCG, L IFG, L mFG, R hip | BMI: 24.7 (3.1), WC (cm): 88.5 (8.1) | BMI, WC | Regions were more widespread in men than in women | Women = 269, A: 55.2 (9.9) | BMI: 22 (3.3), WC (cm): 81.2 (9.8) |
| Hamer and Batty [117], UK | N = 9,652 (from UK Biobank study) Obese = 1,805, A: 55 (7.3) | MRI: GMV | ↑ BMI, WHR, total fat mass, ↓ GMV | OW = 4,167, A: 56 (7.5) | BMI, WHR, total FM, FM index (total FM (kg)/height (m)) | Combination of overall obesity (BMI) and central obesity (WHR) was associated with the lowest GMV | Lean = 3,680, A: 54.7 (7.5) | ↑ BMI, ↓ Pu, Pa, Nac | ↑ WHR, ↓ Th, Cn, Pa | ↑ Fat index, ↓ Pu, Pa, Nac |
| Croll et al. [118], Netherlands | N = 3,648 (from Rotterdam Study) Cross-sectional study = 3,648, A: 65.9 (11.1) | MRI: GMV, WMV | ↑ BMI and FM index were cross-sectionally associated with ↓ WMV | Longitudinal study = 1,844, A: 60.9 (9.9) | BMI, DXA: FM index, FFM index | ↑ FFM index was associated with ↑ GMV |
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