White Matter Integrity Abnormalities in Healthy Overweight Individuals Revealed by Whole Brain Meta-Analysis of Diffusion Tensor Imaging Studies

Table 1

Characteristics, scanning methods, and neuroimaging alterations of the participants in the 5 studies included in the meta-analysis.

Study	Subjects, n (female, n)		Age, years		BMI (kg/m^2)	Scanner (T)	Diffusion encoding orientations	bvalue (s/mm^2)	Scan time	DTI voxel size (mm^3)	Neuroimaging alterations
	OW/OB	Lean	OW/OB	Lean
Shott et al. [21]	18 (18)	24 (24)	28.7	27.4	34.8	3.0	25	1000	N/A	Thickness = 2.6 mm	Decreased FA observed in bilateral anterior corona radiata, superior corona radiata, sagittal stratum, and external capsule. ADC was greater in the right sagittal stratum and left superior corona radiata.
Papageorgiou et al. [22]	148 (77)	120 (76)	51.7	39.8	NA^a	1.5	15	700	N/A	1 × 1 × 1	Decreased FA observed in superior longitudinal fasciculus R, corticospinal tract R, cingulum (cingulate gyrus) R, cingulum (hippocampus) R, white matter optic radiation R, and inferior longitudinal fasciculus R. No other diffusion index (MD, RD, or AD) difference was found.
Ottino-Gonzalez et al. [23]	31 (19)	21 (11)	31.1	29.9	30.8	3.0	30	1000	4 min 23 sec	Thickness = 2 mm	No differences were found in FA, MD, AD, and RD between groups.
Samara et al. [24]	18 (7)	41 (16)	29.8	29.5	35.7	3.0	23	1400	N/A	2 × 2 × 2	Decreased AD observed. No differences were found in FA, MD, and RD between groups.
Estella et al. [25]	17 (17)	13 (13)	38.0	34.7	33.6	3.0	30	1000	7 min	Thickness = 2 mm	No differences were found in FA, MD, AD, and RD between groups.

^aThe overweight group with BMI between 25.0 and 29.9 had 96 members; the obese group with BMI ≥30.0 had 52 members. AD: axial diffusivity; ADC: apparent diffusion coefficient; BMI: body mass index; FA: fractional anisotropy; L: left; MD: mean diffusivity; N/A: not available; OB, obese; OW, overweight; R: right; RD: radial diffusivity.