Long-term exposure to low-concentration PM2.5 and heart disease in older men in Perth, Australia: The Health in Men Study.

Exposure to particulate matter with an aerodynamic diameter less than or equal to 2.5 µm (PM2.5) is associated with increased risk of heart disease, but less is known about the relationship at low concentrations. This study aimed to determine the dose-response relationship between long-term PM2.5 exposure and risk of incident ischemic heart disease (IHD), incident heart failure (HF), and incident atrial fibrillation (AF) in older men living in a region with relatively low ambient air pollution. Methods: PM2.5 exposure was estimated for 11,249 older adult males who resided in Perth, Western Australia and were recruited from 1996 to 1999. Participants were followed until 2018 for the HF and AF outcomes, and until 2017 for IHD. Cox-proportional hazards models, using age as the analysis time, and adjusting for demographic and lifestyle factors were used. PM2.5 was entered as a restricted cubic spline to model nonlinearity. Results: We observed a mean PM2.5 concentration of 4.95 µg/m3 (SD 1.68 µg/m3) in the first year of recruitment. After excluding participants with preexisting disease and adjusting for demographic and lifestyle factors, PM2.5 exposure was associated with a trend toward increased incidence of IHD, HF, and AF, but none were statistically significant. At a PM2.5 concentration of 7 µg/m3 the hazard ratio for incident IHD was 1.04 (95% confidence interval [CI] = 0.86, 1.25) compared with the reference category of 1 µg/m3. Conclusions: We did not observe a significant association between long-term exposure to low-concentration PM2.5 air pollution and IHD, HF, or AF.

Evaluation of brain structure and metabolism in currently depressed adults with a history of childhood trauma.

Structural differences in the dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), hippocampus, and amygdala were reported in adults who experienced childhood trauma; however, it is unknown whether metabolic differences accompany these structural differences. This multimodal imaging study examined structural and metabolic correlates of childhood trauma in adults with major depressive disorder (MDD). Participants with MDD completed the Childhood Trauma Questionnaire (CTQ, n = 83, n = 54 female (65.1%), age: 30.4 ± 14.1) and simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI). Structure (volume, n = 80, and cortical thickness, n = 81) was quantified from MRI using Freesurfer. Metabolism (metabolic rate of glucose uptake) was quantified from dynamic 18F-fluorodeoxyglucose (FDG)-PET images (n = 70) using Patlak graphical analysis. A linear mixed model was utilized to examine the association between structural/metabolic variables and continuous childhood trauma measures while controlling for confounding factors. Bonferroni correction was applied. Amygdala volumes were significantly inversely correlated with continuous CTQ scores. Specifically, volumes were lower by 7.44 mm3 (95% confidence interval [CI]: -12.19, -2.68) per point increase in CTQ. No significant relationship was found between thickness/metabolism and CTQ score. While longitudinal studies are required to establish causation, this study provides insight into potential consequences of, and therefore potential therapeutic targets for, childhood trauma in the prevention of MDD. This work aims to reduce heterogeneity in MDD studies by quantifying neurobiological correlates of trauma within MDD. It further provides biological targets for future interventions aimed at preventing MDD following trauma. To our knowledge, this is the first simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) study to assess both structure and metabolism associated with childhood trauma in adults with MDD.

Risk of Fractures in Stroke Patients Treated With a Selective Serotonin Reuptake Inhibitor: A Systematic Review and Meta-Analysis.

Background and Purpose: Stroke survivors have an increased risk of depression and bone fractures. Selective serotonin reuptake inhibitors (SSRIs) have been associated with an increased risk of fractures in observational studies. Several randomized controlled trials (RCTs) reporting the effect of SSRIs on the risk of fractures in stroke survivors have been published recently but have not been subject to a meta-analysis. We aimed to determine the risk of fractures associated with the use of SSRIs, and the risk of falls, seizures, and recurrent strokes as possible mediators of fractures, in stroke survivors. Methods: We conducted a systematic review and meta-analysis of RCTs of SSRIs in stroke survivors according to a protocol registered in PROSPERO (CRD42020192632). Web of Science, EMBASE, PsycINFO, and Ovid Medline/PubMed bibliographic databases, clinical trial registers, and grey literature sources were searched. RCTs of SSRIs versus placebo or no intervention that report the risk of fractures in adult survivors of hemorrhagic or ischemic stroke were included. Two reviewers independently screened search results and extracted data. Meta-analyses were conducted for each outcome using the Mantel-Haenszel random-effects models. Results: The searches yielded 683 records, of which 4 RCTs of 6 months duration with a total of 6549 participants were included in the meta-analysis: 3 studies of fluoxetine and 1 study of citalopram. Treatment with an SSRI for 6 months increased the risk of fractures with a risk ratio of 2.36 (95% CI, 1.64­3.39) compared with placebo. The risk of falls, seizures, and recurrent stroke was not statistically significantly increased. Only studies of fluoxetine and citalopram were available for inclusion in the review, and hence the generalizability of the findings to other SSRIs is uncertain. Conclusions: Based on available RCTs of fluoxetine and citalopram, SSRIs used for 6 months doubled the risk of fractures in stroke survivors. Registration: https://www.crd.york.ac.uk/prospero/; Unique identifier: CRD42020192632.

m6A mRNA Methylation Is Essential for Oligodendrocyte Maturation and CNS Myelination.

The molecular mechanisms that govern the maturation of oligodendrocyte lineage cells remain unclear. Emerging studies have shown that N6-methyladenosine (m6A), the most common internal RNA modification of mammalian mRNA, plays a critical role in various developmental processes. Here, we demonstrate that oligodendrocyte lineage progression is accompanied by dynamic changes in m6A modification on numerous transcripts. In vivo conditional inactivation of an essential m6A writer component, METTL14, results in decreased oligodendrocyte numbers and CNS hypomyelination, although oligodendrocyte precursor cell (OPC) numbers are normal. In vitro Mettl14 ablation disrupts postmitotic oligodendrocyte maturation and has distinct effects on OPC and oligodendrocyte transcriptomes. Moreover, the loss of Mettl14 in oligodendrocyte lineage cells causes aberrant splicing of myriad RNA transcripts, including those that encode the essential paranodal component neurofascin 155 (NF155). Together, our findings indicate that dynamic RNA methylation plays an important regulatory role in oligodendrocyte development and CNS myelination.