Article Figures & Data
- Figure 1
Statistical significance from association analyses results between systolic blood pressure and diffusion metrics across white matter (WM) tracts. (A) Fractional anisotropy, (B) Mean diffusivity, (C) Orientation Dispersion Index, (D) Isotropic (free) water volume fraction, and (E) Intracellular volume fraction—a measure of neurite density. The colour bars represent −log 10 p values from multivariable regression models. Only WM tracts reaching significance after Bonferroni correction are coloured.
- Figure 2
(A) Statistical significance from association analyses results between systolic blood pressure (SBP) and diffusion metrics across white matter tracts. The colour bars represent p values from multivariable regression models. Only p values reaching significance after Bonferroni correction are coloured. (B) Average percentage change in DTI metrics for each 10 mm Hg increase in SBP across white matter tracts. The colour bars represent the percentage change. Only values reaching significance after Bonferroni correction are coloured. DTI, diffusion tensor imaging; FA, fractional anisotropy; ICVF, intracellular volume fraction; ISOVF, isotropic (free) water volume fraction; MD, mean diffusivity; SBP, systolic blood pressure.
- Figure 3
Average percentage change in DTI metrics for each 10 mm Hg increase in systolic blood pressure (SBP) across white matter (WM) tracts: (A) Fractional anisotropy (FA), (B) mean diffusivity, (C) Orientation Dispersion (OD) Index, (D) Isotropic (free) water volume fraction (ISOVF) and (E) Intracellular volume fraction (ICVF)—a measure of neurite density. Red colour represents positive association and blue colour represents negative association. Only WM tracts reaching significance after Bonferroni correction are coloured.
- Figure 4
Statistical significance from mediation analyses results depicting DTI metrics which significantly mediated the effects of systolic blood pressure on fluid intelligence across white matter (WM) tracts. (A) Fractional anisotropy, (B) mean diffusivity, (C) Orientation Dispersion Index, (D) Isotropic (free) water volume fraction and (E) Intra-ellular volume fraction—a measure of neurite density. The colour bars represent −log 10 p values from mediation analyses. Only WM tracts reaching significance after Bonferroni correction are coloured. DTI, diffusion tensor imaging.
- Figure 5
(A) Mediation analyses results with diffusion metrics highlighted which significantly mediated the effects of systolic blood pressure (SBP) on fluid intelligence across white matter (WM) tracts. Colour bars represent p values from mediation analyses. Only p values reaching significance after Bonferroni correction are highlighted. (B) Average mediated effects proportion of SBP thorough WM tract diffusion metrics on fluid intelligence. Colour bars represent the average mediated effects proportion. Only average mediated effects associated with p values reaching significance after Bonferroni correction are highlighted. FA, fractional anisotropy; ICVF, intracellular volume fraction; ISOVF, isotropic (free) water volume fraction; MD, mean diffusivity; OD, ISOVF.
- Table 1
Baseline characteristics of the studied population
Overall Normal SBP Elevated SBP P value n 31 363 15 913 15 450 Age (years), mean (SD) 63.81 (7.66) 61.88 (7.60) 65.79 (7.21) <0.001 Male sex, n (%) 14 840 (47.3) 6320 (39.7) 8520 (55.1) <0.001 Ethnic background, n (%) 0.07 Asian 381 (1.2) 201 (1.3) 180 (1.2) Black 156 (0.5) 69 (0.4) 87 (0.6) Mixed 128 (0.4) 77 (0.5) 51 (0.3) Other 159 (0.5) 86 (0.5) 73 (0.5) White 30 459 (97.4) 15 435 (97.3) 15 021 (97.5) European ancestry, n (%) 27 444 (87.5) 13 758 (86.5) 13 684 (88.6) <0.001 Smoking status, n (%) <0.001 Never 19 155 (61.1) 10 039 (63.1) 9116 (59.0) Previous 10 288 (32.8) 4812 (30.2) 5476 (35.4) Current 1920 (6.1) 1062 (6.7) 858 (5.6) BMI (kg/m2), mean (SD) 26.52 (4.17) 25.73 (3.93) 27.34 (4.25) <0.001 SBP (mmHg), mean (SD) 138.7 (18.6) 125.1 (10.1) 152.6 (14.6) <0.001 DBP (mmHg), mean (SD) 81.4 (9.9) 76.5 (7.3) 86.5 (9.5) <0.001 LDL-C (mmol/L), mean (SD) 3.59 (0.83) 3.51 (0.81) 3.66 (0.84) <0.001 Haemoglobin A1c (%), mean (SD) 5.35 (0.46) 5.31 (0.43) 5.39 (0.48) <0.001 Atrial fibrillation, n (%) 895 (2.9) 392 (2.5) 503 (3.3) <0.001 Diabetes mellitus, n (%) 1155 (3.7) 448 (2.8) 707 (4.6) <0.001 Elevated SBP was defined as ≥140 mm Hg.
BMI, body mass index; DBP, diastolic blood pressure; LDL-C, low-density lipoprotein cholesterol; SBP, systolic blood pressure.
- Table 2
Association results between systolic blood pressure and measures of cognitive function available in UK Biobank
Cognitive outcome Beta SE P value Prospective memory −0.01 0.009 0.28 Pairs matching −0.001 0.002 0.73 Fluid intelligence −0.05 0.007 <0.001 Reaction time −0.08 0.34 0.81 Symbol digit substitution −0.038 0.02 0.04 Trail making A 0.002 0.003 0.43 Trail making B 0.008 0.005 0.08 Bonferroni corrected p value significance threshold: 0.0071.
Statistically significant differences are marked with bold text.
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