Impact of autism genetic risk on brain connectivity: a mechanism for the female protective effect.

The biological mechanisms underlying the greater prevalence of autism spectrum disorder in males than females remain poorly understood. One hypothesis posits that this female protective effect arises from genetic load for autism spectrum disorder differentially impacting male and female brains. To test this hypothesis, we investigated the impact of cumulative genetic risk for autism spectrum disorder on functional brain connectivity in a balanced sample of boys and girls with autism spectrum disorder and typically developing boys and girls (127 youth, ages 8-17). Brain connectivity analyses focused on the salience network, a core intrinsic functional connectivity network which has previously been implicated in autism spectrum disorder. The effects of polygenic risk on salience network functional connectivity were significantly modulated by participant sex, with genetic load for autism spectrum disorder influencing functional connectivity in boys with and without autism spectrum disorder but not girls. These findings support the hypothesis that autism spectrum disorder risk genes interact with sex differential processes, thereby contributing to the male bias in autism prevalence and proposing an underlying neurobiological mechanism for the female protective effect.

Sex Differences in Functional Connectivity of the Salience, Default Mode, and Central Executive Networks in Youth with ASD.

Autism spectrum disorder (ASD) is associated with the altered functional connectivity of 3 neurocognitive networks that are hypothesized to be central to the symptomatology of ASD: the salience network (SN), default mode network (DMN), and central executive network (CEN). Due to the considerably higher prevalence of ASD in males, however, previous studies examining these networks in ASD have used primarily male samples. It is thus unknown how these networks may be differentially impacted among females with ASD compared to males with ASD, and how such differences may compare to those observed in neurotypical individuals. Here, we investigated the functional connectivity of the SN, DMN, and CEN in a large, well-matched sample of girls and boys with and without ASD (169 youth, ages 8-17). Girls with ASD displayed greater functional connectivity between the DMN and CEN than boys with ASD, whereas typically developing girls and boys differed in SN functional connectivity only. Together, these results demonstrate that youth with ASD exhibit altered sex differences in these networks relative to what is observed in typical development, and highlight the importance of considering sex-related biological factors and participant sex when characterizing the neural mechanisms underlying ASD.

Split course palliative radiotherapy for advanced lung cancer with 3D planning based analysis of outcome: a retrospective review.

BACKGROUND: Durable palliation of advanced lung cancer is a common objective for radiation oncologists. However, there is no consensus on how to deliver the radiation course. Herein we report our experience of using split course radiotherapy and our assessment of outcomes based on planning from three-dimensional (3D) simulation before each treatment course. METHODS: All lung cancer patients from 2006-2020 were identified. Of these, 52 patients received a split course treatment of 50-60 Gy in 18-25 fractions intended to provide durable palliation for disease not amenable to curative therapy. Treatment involved 3D planning with repeat computed tomography (CT) simulation prior to the second course. Survival and symptomatic response were analyzed via chart review. We categorized rapid responders versus non-rapid responders from the initial radiation course based on ≥30% gross tumor volume (GTV) reduction at the second CT simulation. We evaluated the impact of response on overall survival and palliative response. RESULTS: Among our cohort treated with split course palliative radiotherapy, 33 (63%) had a rapid response to initial treatment. There was no difference in survival between groups [hazard ratio (HR) =1.30, P=0.47]. There was no significant difference in palliative response rates between rapid and non-rapid responders. On multivariable analysis, only female sex (HR =0.26, P<0.01) and receipt of systemic therapy following radiotherapy (HR =0.19, P<0.01) were associated with improved survival. CONCLUSIONS: There is currently significant practice pattern variability for palliative lung radiotherapy. Split course palliative radiation of 50-60 Gy in 18-25 fractions represents an option to consider for patients with advanced lung cancer who do not undergo definitive therapy and may benefit from a higher dose regimen. Our retrospective review suggests that rapid tumor response in a split course model does not predict survival or symptomatic response. Prospective studies are needed to further define which lung cancer patients may benefit from higher dose regimens.