Effect of CGRP inhibitors on interictal cerebral hemodynamics in individuals with migraine.

Introduction: Calcitonin gene-related peptide (CGRP) plays an important role in cerebral vasodilation, so here we aim to quantify the impact of CGRP monoclonal antibody (mAb) therapy on cerebral hemodynamics. Methods: In 23 patients with chronic and episodic migraine, cerebral hemodynamic monitoring was performed (1) prior to and (2) 3-months into CGRP-mAb therapy. Transcranial Doppler monitored cerebral blood flow velocity (CBFv) in the middle cerebral artery (MCA) and posterior cerebral artery (PCA), from which cerebrovascular reactivity (CVR) and cerebral autoregulation (CA; Mx-index) were calculated. Results: CA was similar off and on treatment, in the MCA (p = 0.42) and PCA (p = 0.72). CVR was also unaffected by treatment, in the MCA (p = 0.38) and PCA (p = 0.92). CBFv and blood pressure were also unaffected. The subgroup of clinical responders (>50% reduction in migraine frequency) exhibited a small reduction in MCA-CBFv (6.0 cm/s; IQR: 1.1-12.4; p = 0.007) and PCA-CBFv (8.9 cm/s; IQR: 6.9-10.3; p = 0.04). Discussion: Dynamic measures of cerebrovascular physiology were preserved after 3 months of CGRP-mAb therapy, but a small reduction in CBFv was observed in patients who responded to treatment. Subgroup findings should be interpreted cautiously, but further investigation may clarify if CBFv is dependent on the degree of CGRP inhibition or may serve as a biomarker of drug sensitivity.

Preeclampsia Onset, Days to Delivery, and Autism Spectrum Disorders in Offspring: Clinical Birth Cohort Study.

BACKGROUND: Maternal preeclampsia is associated with a risk of autism spectrum disorders (ASD) in offspring. However, it is unknown whether the increased ASD risk associated with preeclampsia is due to preeclampsia onset or clinical management of preeclampsia after onset, as clinical expectant management of preeclampsia allows pregnant women with this complication to remain pregnant for potentially weeks depending on the onset and severity. Identifying the risk associated with preeclampsia onset and exposure provides evidence to support the care of high-risk pregnancies and reduce adverse effects on offspring. OBJECTIVE: This study aimed to fill the knowledge gap by assessing the ASD risk in children associated with the gestational age of preeclampsia onset and the number of days from preeclampsia onset to delivery. METHODS: This retrospective population-based clinical cohort study included 364,588 mother-child pairs of singleton births between 2001 and 2014 in a large integrated health care system in Southern California. Maternal social demographic and pregnancy health data, as well as ASD diagnosis in children by the age of 5 years, were extracted from electronic medical records. Cox regression models were used to assess hazard ratios (HRs) of ASD risk in children associated with gestational age of the first occurrence of preeclampsia and the number of days from first occurrence to delivery. RESULTS: Preeclampsia occurred in 16,205 (4.4%) out of 364,588 pregnancies; among the 16,205 pregnancies, 2727 (16.8%) first occurred at <34 weeks gestation, 4466 (27.6%) first occurred between 34 and 37 weeks, and 9012 (55.6%) first occurred at ≥37 weeks. Median days from preeclampsia onset to delivery were 4 (IQR 2,16) days, 1 (IQR 1,3) day, and 1 (IQR 0,1) day for those first occurring at <34, 34-37, and ≥37 weeks, respectively. Early preeclampsia onset was associated with greater ASD risk (P=.003); HRs were 1.62 (95% CI 1.33-1.98), 1.43 (95% CI 1.20-1.69), and 1.23 (95% CI 1.08-1.41), respectively, for onset at <34, 34-37, and ≥37 weeks, relative to the unexposed group. Within the preeclampsia group, the number of days from preeclampsia onset to delivery was not associated with ASD risk in children; the HR was 0.995 (95% CI 0.986-1.004) after adjusting for gestational age of preeclampsia onset. CONCLUSIONS: Preeclampsia during pregnancy was associated with ASD risk in children, and the risk was greater with earlier onset. However, the number of days from first preeclampsia onset to delivery was not associated with ASD risk in children. Our study suggests that ASD risk in children associated with preeclampsia is not increased by expectant management of preeclampsia in standard clinical practice. Our results emphasize the need to identify effective approaches to preventing the onset of preeclampsia, especially during early pregnancy. Further research is needed to confirm if this finding applies across different populations and clinical settings.

Special Operations Cognitive Agility Training (SOCAT) for Special Operations Forces and spouses.

Increasingly complex and unpredictable personnel and operational demands require Special Operations Forces (SOF) members and their families to remain flexible, adaptive, and resilient within ever-changing circumstances. To mitigate the impact of these stressors on psychological health and fitness, researchers and educators at the Uniformed Services University of the Health Sciences (USUHS) developed Special Operations Cognitive Agility Training (SOCAT), a cognitive performance optimization program supported by the United States Special Operations Command (USSOCOM) Preservation of the Force and Family (POTFF). The goal of SOCAT is to enhance cognitive agility, defined as the ability to deliberately adapt cognitive processing strategies in accordance with dynamic shifts in situational and environmental demands, in order to facilitate decision making and adapt to change. Overall, SOCAT emphasizes optimal cognitive performance across different contexts - as well as across various stages of the military lifecycle - to serve as a buffer against biopsychosocial vulnerabilities, environmental and social stressors, military operational demands, and behavioral health problems, including suicide. This paper reviews foundational research behind SOCAT, mechanisms through which SOCAT is anticipated to build psychological resilience, and describes the process of developing and tailoring SOCAT for active duty SOF members and spouses. Limitations and future directions, including an ongoing, randomized controlled program evaluation, are discussed.

The Effect of the Lateral First Metatarsal Head Shape on Hallux Valgus in Forced Turnout in Pre-Pointe Female Ballet Dancers: A Pilot Study.

BACKGROUND: A rounded lateral first metatarsal head shape is associated with higher rates of hallux abducto valgus recurrence following corrective surgery; however, the effect of the lateral first metatarsal head shape on the hallux abduction angle (HAA) has not yet been explored in a nonpathologic, pre-pointe ballet dancer population. The primary purpose of this study was to investigate the effect of the lateral first metatarsal head shape on the HAA when pre-pointe female dancers force their turnout. METHODS: Seventeen female, pre-pointe ballet students (mean age, 10.8 ± 0.95 years) participated in this study. Fluoroscopic images of each dancer's dominant foot were taken, and the lateral first metatarsal head shape was classified visually. Each dancer performed three consecutive stances of natural double-leg upright posture: both functional and forced turnout. HAAs were obtained by marking medial bony landmarks on paper and were compared to photographic measurements. RESULTS: No significant difference was found between the round and angular lateral first metatarsal head shape for the change in HAA from natural double-leg upright posture to forced turnout. Hallux abduction angle significantly increased by 4.6° (P < .001) in forced turnout compared to the natural double-leg upright posture for the photographic method, whereas the paper method demonstrated an increase of 2.6° (P = .007). No statistical differences were found between the paper and photographic methods in measuring the HAA for all stances. CONCLUSIONS: Our findings suggest no association between the HAA and lateral first metatarsal head shape; however, HAA does increase when a dancer assumes forced turnout. The paper method demonstrated similar reliability to the photographic method and shows the potential for future use as a clinical tool in assessing hallux abducto valgus.

Portable cerebral blood flow monitor to detect large vessel occlusion in patients with suspected stroke.

BACKGROUND: Early detection of large vessel occlusion (LVO) facilitates triage to an appropriate stroke center to reduce treatment times and improve outcomes. Prehospital stroke scales are not sufficiently sensitive, so we investigated the ability of the portable Openwater optical blood flow monitor to detect LVO. METHODS: Patients were prospectively enrolled at two comprehensive stroke centers during stroke alert evaluation within 24 hours of onset with National Institutes of Health Stroke Scale (NIHSS) score ≥2. A 70 s bedside optical blood flow scan generated cerebral blood flow waveforms based on relative changes in speckle contrast. Anterior circulation LVO was determined by CT angiography. A deep learning model trained on all patient data using fivefold cross-validation and learned discriminative representations from the raw speckle contrast waveform data. Receiver operating characteristic (ROC) analysis compared the Openwater diagnostic performance (ie, LVO detection) with prehospital stroke scales. RESULTS: Among 135 patients, 52 (39%) had an anterior circulation LVO. The median NIHSS score was 8 (IQR 4-14). The Openwater instrument had 79% sensitivity and 84% specificity for the detection of LVO. The rapid arterial occlusion evaluation (RACE) scale had 60% sensitivity and 81% specificity and the Los Angeles motor scale (LAMS) had 50% sensitivity and 81% specificity. The binary Openwater classification (high-likelihood vs low-likelihood) had an area under the ROC (AUROC) of 0.82 (95% CI 0.75 to 0.88), which outperformed RACE (AUC 0.70; 95% CI 0.62 to 0.78; P=0.04) and LAMS (AUC 0.65; 95% CI 0.57 to 0.73; P=0.002). CONCLUSIONS: The Openwater optical blood flow monitor outperformed prehospital stroke scales for the detection of LVO in patients undergoing acute stroke evaluation in the emergency department. These encouraging findings need to be validated in an independent test set and the prehospital environment.

Validation of the Openwater wearable optical system: cerebral hemodynamic monitoring during a breath-hold maneuver.

Significance: Bedside cerebral blood flow (CBF) monitoring has the potential to inform and improve care for acute neurologic diseases, but technical challenges limit the use of existing techniques in clinical practice. Aim: Here, we validate the Openwater optical system, a novel wearable headset that uses laser speckle contrast to monitor microvascular hemodynamics. Approach: We monitored 25 healthy adults with the Openwater system and concurrent transcranial Doppler (TCD) while performing a breath-hold maneuver to increase CBF. Relative blood flow (rBF) was derived from changes in speckle contrast, and relative blood volume (rBV) was derived from changes in speckle average intensity. Results: A strong correlation was observed between beat-to-beat optical rBF and TCD-measured cerebral blood flow velocity (CBFv), R=0.79; the slope of the linear fit indicates good agreement, 0.87 (95% CI: 0.83 -0.92). Beat-to-beat rBV and CBFv were also strongly correlated, R=0.72, but as expected the two variables were not proportional; changes in rBV were smaller than CBFv changes, with linear fit slope of 0.18 (95% CI: 0.17 to 0.19). Further, strong agreement was found between rBF and CBFv waveform morphology and related metrics. Conclusions: This first in vivo validation of the Openwater optical system highlights its potential as a cerebral hemodynamic monitor, but additional validation is needed in disease states.

Snus use in football: the threat of a new addiction?

The use of Snus, an oral nicotine pouch, is becoming increasingly common in English professional football. As a nicotine product, Snus raises important questions about health and performance for practitioners. The purpose of this short communication is to explain the current regulatory status of Snus, performance relatedeffects, and associated health outcomes. Further, based on player statements and evidence from the general public, we argue that Snus is used as a coping mechanism to deal with the stressors of professional football. Accordingly, the communication concludes with guidance for club-level multidisciplinary interventions to support player welfare, aimed at reducing Snus use as well as future research recommendations.

Characterization of genetic and molecular tools for studying the endogenous expression of Lactate dehydrogenase in Drosophila melanogaster.

Drosophila melanogaster larval development relies on a specialized metabolic state that utilizes carbohydrates and other dietary nutrients to promote rapid growth. One unique feature of the larval metabolic program is that Lactate Dehydrogenase (Ldh) activity is highly elevated during this growth phase when compared to other stages of the fly life cycle, indicating that Ldh serves a key role in promoting juvenile development. Previous studies of larval Ldh activity have largely focused on the function of this enzyme at the whole animal level, however, Ldh expression varies significantly among larval tissues, raising the question of how this enzyme promotes tissue-specific growth programs. Here we characterize two transgene reporters and an antibody that can be used to study Ldh expression in vivo. We find that all three tools produce similar Ldh expression patterns. Moreover, these reagents demonstrate that the larval Ldh expression pattern is complex, suggesting the purpose of this enzyme varies across cell types. Overall, our studies validate a series of genetic and molecular reagents that can be used to study glycolytic metabolism in the fly.

Universal Biomaterial-on-Chip: a versatile platform for evaluating cellular responses on diverse biomaterial substrates.

Microfluidics has emerged as a promising approach for assessing cellular behavior in vitro, providing more physiologically relevant cell culture environments with dynamic flow and shear stresses. This study introduces the Universal Biomaterial-on-Chip (UBoC) device, which enables the evaluation of cell response on diverse biomaterial substrates in a 3D-printed microfluidic device. The UBoC platform offers mechanical stimulation of the cells and monitoring of their response on diverse biomaterials, enabling qualitative and quantitative in vitro analysis both on- and off-chip. Cell adhesion and proliferation were assessed to evaluate the biocompatibility of materials with different physical properties, while mechanical stimulation was performed to investigate shear-dependent calcium signaling in pre-osteoblasts. Moreover, the applicability of the UBoC platform in creating more complex in vitro models by culturing multiple cell types was demonstrated, establishing a dynamic multicellular environment to investigate cellular interfaces and their significance in biological processes. Overall, the UBoC presents an adaptable tool for in vitro evaluation of cellular behavior, offering opportunities for studying various biomaterials and cell interactions in microfluidic environments.

A peer veteran approach to the caring letters suicide prevention program: Preliminary data.

Caring Letters is a prevention program aimed at reducing suicide risk; however, clinical trials indicate mixed results among military and veteran samples. The present study aimed to pilot a new version of the Caring Letters intervention that was adapted to military culture in order to emphasize peer support. The supportive letters, traditionally sent from clinicians, were written by peer veterans (PVs) who volunteered from local Veteran Service Organizations (VSOs). PVs (n = 15) attended a 4-hr workshop to learn about Caring Letters and write six letters to a veteran with a recent hospitalization for suicide risk (hospitalized veterans [HVs]; n = 15 completed a baseline assessment). Letters from PVs were sent to HVs once a month for 6 months following discharge from the psychiatric inpatient unit. The study used a limited efficacy approach to examine feasibility outcomes including implementation procedures, participant recruitment and retention rates, and barriers and facilitators. Acceptability measures examined HV satisfaction, perceived privacy and safety, and PV workshop satisfaction. Among HVs, results suggested that suicidal ideation improved from baseline to follow-up (g = 3.19). Results suggested resilience scores improved among HVs (g = 0.99). Results also suggested a possible reduction in stigma associated with mental health treatment among PVs at 1-month postworkshop assessment. Interpretation of the results is limited by the design and sample size, but the results provide preliminary support for the feasibility and acceptability of a PV approach to Caring Letters. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Neighborhood Disadvantage and Autism Spectrum Disorder in a Population With Health Insurance.

Importance: Family socioeconomic status has been associated with autism spectrum disorder (ASD) diagnoses. Less is known regarding the role of neighborhood disadvantage in the United States, particularly when children have similar access to health insurance. Objective: To evaluate the association between neighborhood disadvantage and the diagnosis of ASD and potential effect modification by maternal and child demographic characteristics. Design, Setting, and Participants: This cohort study examined a retrospective birth cohort from Kaiser Permanente Southern California (KPSC), an integrated health care system. Children born in 2001 to 2014 at KPSC were followed up through KPSC membership records. Electronic medical records were used to obtain an ASD diagnosis up to December 31, 2019, or the last follow-up. Data were analyzed from February 2022 to September 2023. Exposure: Socioeconomic disadvantage at the neighborhood level, an index derived from 7 US census tract characteristics using principal component analysis. Main Outcomes and Measures: Clinical ASD diagnosis based on electronic medical records. Associations between neighborhood disadvantage and ASD diagnosis were determined by hazard ratios (HRs) from Cox regression models adjusted for birth year, child sex, maternal age at delivery, parity, severe prepregnancy health conditions, maternal race and ethnicity, and maternal education. Effect modification by maternal race and ethnicity, maternal education, and child sex was assessed. Results: Among 318 372 mothers with singleton deliveries during the study period, 6357 children had ASD diagnoses during follow-up; their median age at diagnosis was 3.53 years (IQR, 2.57-5.34 years). Neighborhood disadvantage was associated with a higher likelihood of ASD diagnosis (HR, 1.07; 95% CI, 1.02-1.11, per IQR = 2.70 increase). Children of mothers from minoritized racial and ethnic groups (African American or Black, Asian or Pacific Islander, Hispanic or Latinx groups) had increased likelihood of ASD diagnosis compared with children of White mothers. There was an interaction between maternal race and ethnicity and neighborhood disadvantage (difference in log-likelihood = 21.88; P < .001 for interaction under χ24); neighborhood disadvantage was only associated with ASD among children of White mothers (HR, 1.17; 95% CI, 1.09-1.26, per IQR = 2.00 increase). Maternal education and child sex did not significantly modify the neighborhood-ASD association. Conclusions and Relevance: In this study, children residing in more disadvantaged neighborhoods at birth had higher likelihood of ASD diagnosis among a population with health insurance. Future research is warranted to investigate the mechanisms behind the neighborhood-related disparities in ASD diagnosis, alongside efforts to provide resources for early intervention and family support in communities with a higher likelihood of ASD.

Maternal obesity and diabetes during pregnancy and early autism screening score at well-child visits in standard clinical practice.

LAY ABSTRACT: Early intervention and treatment can help reduce disability in children diagnosed with autism spectrum disorder. Screening for autism spectrum disorder in young children identifies those at increased likelihood of diagnosis who may need further support. Previous research has reported that exposure to maternal obesity and diabetes during pregnancy is associated with higher likelihood of autism spectrum disorder diagnosis in children. However, little is known about whether these maternal conditions are associated with how very young children score on autism spectrum disorder screening tools. This study examined associations between exposure to maternal obesity and diabetes during pregnancy and offspring scores on the Quantitative Checklist for Autism in Toddlers, an autism spectrum disorder screening questionnaire administered between 18-24 months at well-child visits. A higher score on the Quantitative Checklist for Autism in Toddlers suggests a higher likelihood of autism spectrum disorder; children with scores 3 or greater are referred to developmental pediatricians for evaluation. Our study found that children of mothers with obesity or diabetes during pregnancy had higher scores than children whose mothers did not have these conditions. Associations with maternal obesity and gestational diabetes diagnosed at or before 26 weeks of pregnancy were also present in children who did not have later autism spectrum disorder diagnoses, suggesting that exposure to these conditions during early pregnancy may be associated with a broad range of social and behavioral abilities. Identifying associations between maternal health conditions and early Quantitative Checklist for Autism in Toddlers screening scores could influence future screening and provision of support for children of mothers with these conditions.

Types of diabetes during pregnancy and risk of depression and anxiety in offspring from childhood to young adulthood.

AIMS: To assess maternal pre-existing type 1 diabetes (T1D), type 2 diabetes (T2D), gestational diabetes mellitus (GDM) during pregnancy and risk of depression and anxiety from childhood to young adulthood in offspring. MATERIALS AND METHODS: This birth cohort included singletons born during 1995-2015, followed using electronic medical records through 2020. Cox regression was used to estimate hazard ratio (HR) of depression or anxiety diagnosis during follow-up associated with in-utero exposure to maternal diabetes. RESULTS: Among 439 590 offspring, 29 891 (6.8%) had depression and 51 918 (11.8%) had anxiety. T1D, followed by T2D and GDM requiring antidiabetes medication were associated with risk of depression and anxiety in offspring. Compared with no diabetes during pregnancy, the adjusted HRs (95% confidence interval) of depression in offspring associated with T1D, T2D or GDM requiring medications were 1.44 (1.09-1.91), 1.30 (1.15-1.47) and 1.18 (1.11-1.26) respectively; conversely, HRs were 0.97 (0.82-1.15) for T2D and 0.99 (0.94-1.04) for GDM without medications. The associations with anxiety followed similar patterns. The significant associations were observed for offspring ages 5-12 and >12-18 years and attenuated for 18-25 years. CONCLUSION: These data suggest that the severity of diabetes (T1D vs. T2D requiring medications vs. GDM requiring medications) during pregnancy may increase the vulnerability of offspring for depression or anxiety.

Validation of the Openwater wearable optical system: cerebral hemodynamic monitoring during a breath hold maneuver.

Bedside cerebral blood flow (CBF) monitoring has the potential to inform and improve care for acute neurologic diseases, but technical challenges limit the use of existing techniques in clinical practice. Here we validate the Openwater optical system, a novel wearable headset that uses laser speckle contrast to monitor microvascular hemodynamics. We monitored 25 healthy adults with the Openwater system and concurrent transcranial Doppler (TCD) while performing a breath-hold maneuver to increase CBF. Relative blood flow (rBF) was derived from the changes in speckle contrast, and relative blood volume (rBV) was derived from the changes in speckle average intensity. A strong correlation was observed between beat-to-beat optical rBF and TCD-measured cerebral blood flow velocity (CBFv), R=0.79; the slope of the linear fit indicates good agreement, 0.87 (95% CI:0.83-0.92). Beat-to-beat rBV and CBFv were strongly correlated, R=0.72, but as expected the two variables were not proportional; changes in rBV were smaller than CBFv changes, with linear fit slope of 0.18 (95% CI:0.17-0.19). Further, strong agreement was found between rBF and CBFv waveform morphology and related metrics. This first in vivo validation of the Openwater optical system highlights its potential as a cerebral hemodynamic monitor, but additional validation is needed in disease states.

Microvascular reperfusion during endovascular therapy: the balance of supply and demand.

BACKGROUND: Endovascular therapy (EVT) has revolutionized the treatment of acute stroke, but large vessel recanalization does not always result in tissue-level reperfusion. Cerebral blood flow (CBF) is not routinely monitored during EVT. We aimed to leverage diffuse correlation spectroscopy (DCS), a novel transcranial optical imaging technique, to assess the relationship between microvascular CBF and post-EVT outcomes. METHODS: Frontal lobe CBF was monitored by DCS in 40 patients undergoing EVT. Baseline CBF deficit was calculated as the percentage of CBF impairment on pre-EVT CT perfusion. Microvascular reperfusion was calculated as the percentage increase in DCS-derived CBF that occurred with recanalization. The adequacy of reperfusion was defined by persistent CBF deficit, calculated as: baseline CBF deficit - microvascular reperfusion. A good functional outcome was defined as 90-day modified Rankin Scale score ≤2. RESULTS: Thirty-six of 40 patients achieved successful recanalization, in whom microvascular reperfusion in itself was not associated with infarct volume or functional outcome. However, patients with good functional outcomes had a smaller persistent CBF deficit (median 1% (IQR -11%-16%)) than patients with poor outcomes (median 28% (IQR 2-50%)) (p=0.02). Smaller persistent CBF deficit was also associated with smaller infarct volume (p=0.004). Multivariate models confirmed that persistent CBF deficit was independently associated with infarct volume and functional outcome. CONCLUSIONS: CBF augmentation alone does not predict post-EVT outcomes, but when microvascular reperfusion closely matches the baseline CBF deficit, patients experience favorable clinical and radiographic outcomes. By recognizing inadequate reperfusion, bedside CBF monitoring may provide opportunities to personalize post-EVT care aimed at CBF optimization.

Prenatal Exposure to Gestational Diabetes Mellitus is Associated with Mental Health Outcomes and Physical Activity has a Modifying Role.

Background: Studies suggest a link between prenatal gestational diabetes mellitus (GDM) exposure and poor mental health outcomes. We examined associations between prenatal GDM exposure and depressive and anxiety symptoms in children and assessed physical activity as a potential modifier of these associations. Method: Seventy children (AgeM(SD): 12(2.0), 56% GDM, 59% female) and their parents completed surveys: Center for Epidemiological Studies Depression Scale for Children (CES-DC), State-Trait Anxiety Inventory for Children (STAIC), Child Behavior Checklist (CBCL), and 3-day physical activity recall (3DPAR). Associations between mental health measures with GDM exposure and interactions between GDM exposure and child moderate-to-vigorous physical activity (MVPA) were assessed using regression. Results: GDM-exposed children had higher anxiety (p = 0.03) and internalizing symptoms (CBCL) (p = 0.04) than unexposed children. There was an interaction between GDM exposure and child MVPA on anxiety (p = 0.02), internalizing (p = 0.04) and externalizing symptoms (p = 0.004). In the low MVPA group, GDM exposed children had more depressive (p = 0.03), anxiety (p = 0.003), and internalizing symptoms (p = 0.03) than unexposed children. In the high MVPA group, there were no group differences except with externalizing symptoms (p = 0.04). Conclusion: Prenatal GDM is associated with higher anxiety and internalizing symptoms in children. Child MVPA modified the relationship between GDM exposure and mental health outcomes suggesting that physical activity during childhood could mitigate the negative mental health outcomes associated with prenatal GDM exposure.

Prenatal air pollution, maternal immune activation, and autism spectrum disorder.

BACKGROUND: Autism Spectrum Disorder (ASD) risk is highly heritable, with potential additional non-genetic factors, such as prenatal exposure to ambient particulate matter with aerodynamic diameter < 2.5 µm (PM2.5) and maternal immune activation (MIA) conditions. Because these exposures may share common biological effect pathways, we hypothesized that synergistic associations of prenatal air pollution and MIA-related conditions would increase ASD risk in children. OBJECTIVES: This study examined interactions between MIA-related conditions and prenatal PM2.5 or major PM2.5 components on ASD risk. METHODS: In a population-based pregnancy cohort of children born between 2001 and 2014 in Southern California, 318,751 mother-child pairs were followed through electronic medical records (EMR); 4,559 children were diagnosed with ASD before age 5. Four broad categories of MIA-related conditions were classified, including infection, hypertension, maternal asthma, and autoimmune conditions. Average exposures to PM2.5 and four PM2.5 components, black carbon (BC), organic matter (OM), nitrate (NO3-), and sulfate (SO42-), were estimated at maternal residential addresses during pregnancy. We estimated the ASD risk associated with MIA-related conditions, air pollution, and their interactions, using Cox regression models to adjust for covariates. RESULTS: ASD risk was associated with MIA-related conditions [infection (hazard ratio 1.11; 95% confidence interval 1.05-1.18), hypertension (1.30; 1.19-1.42), maternal asthma (1.22; 1.08-1.38), autoimmune disease (1.19; 1.09-1.30)], with higher pregnancy PM2.5 [1.07; 1.03-1.12 per interquartile (3.73 µg/m3) increase] and with all four PM2.5 components. However, there were no interactions of each category of MIA-related conditions with PM2.5 or its components on either multiplicative or additive scales. CONCLUSIONS: MIA-related conditions and pregnancy PM2.5 were independently associations with ASD risk. There were no statistically significant interactions of MIA conditions and prenatal PM2.5 exposure with ASD risk.