Background: Cerebral small vessel disease (SVD) is a common cause of stroke, mild cognitive impairment, dementia and physical impairments. Differences in SVD incidence or severity between males and females are unknown. We assessed sex differences in SVD by assessing the male-to-female ratio (M:F) of recruited participants and incidence of SVD, risk factor presence, distribution, and severity of SVD features.Methods: We assessed four recent systematic reviews on SVD and performed a supplementary search of MEDLINE to identify studies reporting M:F ratio in covert, stroke, or cognitive SVD presentations (registered protocol: CRD42020193995). We meta-analyzed differences in sex ratios across time, countries, SVD severity and presentations, age and risk factors for SVD.Results: Amongst 123 relevant studies (n = 36,910 participants) including 53 community-based, 67 hospital-based and three mixed studies published between 1989 and 2020, more males were recruited in hospital-based than in community-based studies [M:F = 1.16 (0.70) vs. M:F = 0.79 (0.35), respectively; p < 0.001]. More males had moderate to severe SVD [M:F = 1.08 (0.81) vs. M:F = 0.82 (0.47) in healthy to mild SVD; p < 0.001], and stroke presentations where M:F was 1.67 (0.53). M:F did not differ for recent (2015–2020) vs. pre-2015 publications, by geographical region, or age. There were insufficient sex-stratified data to explore M:F and risk factors for SVD.Conclusions: Our results highlight differences in male-to-female ratios in SVD severity and amongst those presenting with stroke that have important clinical and translational implications. Future SVD research should report participant demographics, risk factors and outcomes separately for males and females.Systematic Review Registration: [PROSPERO], identifier [CRD42020193995].

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Background: Autism is considered to entail a social impairment whereby autistic people experience difficulty interpreting others' mental states. However, recent research has shown that nonautistic people also have difficulty understanding the mental states of autistic people. This mismatch of understanding may explain lower rapport in interactions between autistic and nonautistic people. As mental states can be expressed externally through socially normed signals, it is important to investigate the role of such signals in autistic, nonautistic, and mixed interactions. This study explores variability in two social signals between autistic, nonautistic, and mixed interactions, and how their use may affect rapport within interactions. Methods: Videos from a previous study of autistic, nonautistic, and mixed pair interactions in a diffusion chain context in which participants were aware of others' diagnostic status were video coded for mutual gaze and backchanneling as candidate indicators of interactional rapport. Results: Although use of mutual gaze and backchanneling was lower in mixed pairs than in nonautistic pairs, corresponding to lower ratings of interactional rapport, less backchanneling in autistic pairs of both nonverbal and verbal subtypes corresponded to higher ratings of rapport. Conclusions: We observed differences in the use of candidate rapport markers between autistic, mixed, and nonautistic interactions, which did not map onto patterns of rapport scores, suggesting differences in reliance on these cues between autistic and nonautistic people. These results suggest that visible markers of rapport may vary by neurotype or pairing and give clues to inform future investigations of autistic interaction.

Importance: Preterm birth and socioeconomic status (SES) are associated with brain structure in childhood, but the relative contributions of each during the neonatal period are unknown. Objective: To investigate associations of gestational age (GA) and SES with neonatal brain morphology, by testing 3 hypotheses: GA and SES are associated with brain morphology; associations between SES and brain morphology vary across the GA range, and; associations between SES and brain structure/morphology depend on how SES is operationalized. Design: Cohort study, recruited 2016-2021. Setting: Single center, UK. Participants: 170 preterm infants and 91 term infants with median (range) birth GA 30+0 (22+1-32+6) and 39+4 (36+3-42+1) weeks, respectively. Exclusion criteria: major congenital malformation, chromosomal abnormality, congenital infection, cystic periventricular leukomalacia, hemorrhagic parenchymal infarction, post-hemorrhagic ventricular dilatation. Exposures: Using linear ridge regression models, we investigated associations of GA and SES, operationalized at the neighborhood-level (Scottish Index of Multiple Deprivation), family-level (parental education and occupation) and subjectively (WHO Quality of Life), with regional brain volumes and cortical morphology. Main outcomes/measures: Brain volume (85 parcels) and 5 whole-brain cortical morphology measures (gyrification index, thickness, sulcal depth, curvature, surface area) at term-equivalent age. Results: In fully adjusted models, GA associated with a higher proportion of brain volumes (22/85 [26%], β range |-0.13| to |0.22|) than neighborhood SES (1/85 [1%], β=0.17). GA associated with cortical surface area (β=0.10 [95% confidence interval (CI) 0.02-0.18]) and gyrification index (β=0.16 [95% CI 0.07-0.25]); neighborhood SES did not. Family-level SES associated with the volumes of more parcels than neighborhood SES, but it did not have as extensive associations with brain structure as GA. There were interactions between GA and both family- and subjective-level SES measures on brain structure. Conclusions/relevance: In a UK cohort, GA and SES impact neonatal brain morphology, but low GA has more widely distributed effects on neonatal brain structure than neighborhood-level, family-level and subjective measures of SES. Further work is warranted to elucidate the mechanisms embedding GA and level-specific SES in early brain development.

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