Mechanisms of neuroimmune and mitochondrial dysfunction have been repeatedly implicated in autism spectrum disorder (ASD). To examine these mechanisms in ASD individuals, we measured the in vivo expression of the 18 kDa translocator protein (TSPO), an activated glial marker expressed on mitochondrial membranes. Participants underwent scanning on a simultaneous magnetic resonance-positron emission tomography (MR-PET) scanner with the second-generation TSPO radiotracer [ 11 C]PBR28. By comparing TSPO in 15 young adult males with ASD with 18 age-and sex-matched controls, we showed that individuals with ASD exhibited lower regional TSPO expression in several brain regions, including the bilateral insular cortex, bilateral precuneus/posterior cingulate cortex, and bilateral temporal, angular, and supramarginal gyri, which have previously been implicated in autism in functional MR imaging studies. No brain region exhibited higher regional TSPO expression in the ASD group compared with the control group. A subset of participants underwent a second MR-PET scan after a median interscan interval of 3.6 months, and we determined that TSPO expression over this period of time was stable and replicable. Furthermore, voxelwise analysis confirmed lower regional TSPO expression in ASD at this later time point. Lower TSPO expression in ASD could reflect abnormalities in neuroimmune processes or mitochondrial dysfunction.

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Introduction Traumatic brain injury (TBI) may alter the course of neuropsychiatric symptom (NPS) onset during dementia development. The connection among TBI, NPS, and dementia progression is of increasing interest to researchers and clinicians. Methods Incidence of NPS was examined in participants with normal cognition who progressed to all‐cause dementia based on whether TBI history was present (n = 130) or absent (n = 849). Survival analyses were used to examine NPS incidence across 7.6 ± 3.0 years of follow‐up. Results Participants with TBI history had increased prevalence and incidence of apathy (44.7% vs 29.9%, P = .0062; HRadj. = 1.708, P = .0018) and motor disturbances (17.2% vs 9.5%, P = .0458; HRadj. = 2.023, P = .0168), controlling for demographics and type of dementia diagnosis. Earlier anxiety onset was associated with TBI (692 days prior to dementia diagnosis vs 161 days, P = .0265). Discussion History of TBI is associated with increased risk for and earlier onset of NPS in the trajectory of dementia development.