44 Chapter 3 3.4 RESULTS A total of 2297 participants were included in the current study. A flowchart showing the inclusions/exclusions of the study is shown in figure 3.1. Supplementary table S.3.9.1 contains a comparison of the baseline characteristics of the participants included (n=2297) and excluded (n=2317) from our study. As to be expected, cardiovascular risk factors, such as diabetes, coronary artery disease, and hypertension were significantly more prevalent in the excluded group. Moreover, the excluded group is older and has a lower BMI. The mean age at baseline of the included community-dwelling older adults was 74.5±4.7 years and the mean time to follow-up was 5.2 ± 0.2 years. The characteristics of the study sample, including cardiovascular risk factors, are shown in Table 3.1. At baseline 153 participants (7%) had subcortical infarcts, 381 participants (17%) had microbleeds, 358 participants (16%) had enlarged perivascular spaces, 428 participants (19%) had cerebellar infarcts, and 176 participants (8%) had cortical infarcts (table 3.2). The average WMH volume at baseline was 16.6 ± 17.2 ml. At follow-up, 68 participants (3%) had new subcortical infarcts, 299 participants (13%) had new microbleeds, 39 participants (2%) had new enlarged perivascular spaces, 168 participants (7%) had new cerebellar infarcts and 123 participants (5%) had new cortical infarcts (table 3.2). The average WMH volume at follow-up was 22.3 ± 22.2 ml. A detailed description of the cerebrovascular changes on MRI of the participants can be found in supplementary table S.3.9.2. 3.4.1 Periventricular/confluent WMH shape and progression of cerebrovascular changes A more irregular shape of periventricular/confluent WMH (lower solidity (B: 0.91 (95% CI: 0.59–1.23); p<0.001), lower convexity (B: 1.94 (1.62–2.26); p<0.001), higher concavity index (B: 2.28 (1.95–2.61); p<0.001), higher fractal dimension (B: 2.62 (2.31– 2.93); p<0.001)) at baseline was significantly associated with a larger increase in WMH volume over 5.2 years (Table 3.3 and supplementary figure S.3.9.2). Furthermore, a more irregular shape of periventricular/confluent WMH at baseline was associated with new subcortical infarcts (lower solidity (OR: 1.75 (95% CI: 1.16–2.62); p<0.001); lower convexity (OR: 1.44 (1.17–1.76); p<0.001); higher concavity index (OR: 1.58 (1.29–1.94); p<0.001); higher fractal dimension (OR: 1.91 (1.49–2.44); p<0.001)), new microbleeds (lower solidity (OR: 1.24 (1.07–1.44); p=0.004); lower convexity (OR: 1.16 (1.04–1.30); p=0.009); higher concavity index (OR: 1.24 (1.11–1.39); p<0.001); higher fractal dimension (OR: 1.47 (1.30–1.65); p<0.001)), new enlarged perivascular spaces (lower convexity (OR: 1.34 (1.05–1.71); p<0.017); higher concavity index (OR: 1.34 (1.05–1.71); p<0.020)), and new cerebellar infarcts at follow-up (lower convexity (OR:
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