Given the profound effect of traumatic stress on aspects of brain functioning, it is unsurprising that PTSD is associated with an approximately 2-fold increase in risk for dementia (Günak et al., 2020). The impact of PTSD on risk for dementia may vary based on genetic risk, such that the effect of PTSD on dementia risk is more robust in carriers of Apolipoprotein isoform 4, commonly referred to as APOEε4 (Averill et al., 2019; Lawrence, Rippey, Welikson, Pietrzak, & Adams, 2023; Logue et al., 2022). APOEε4 is the most prominent genetic risk factor for the development of Alzheimer’s disease (AD) (Bellenguez et al., 2022; Corder et al., 1993; Lendon, Ashall, & Goate, 1997). Among individuals without AD, APOE ε4 is also associated with poorer cognition and complex health conditions (Reinvang, Winjevoll, Rootwelt, & Espeseth, 2010). While there is substantial evidence in older individuals, some studies have also demonstrated early developmental changes in brain structures and function that varied by APOEε4 status (Iacono & Feltis, 2019), with healthy young ε4 carriers (age 3–20) displaying smaller hippocampi, larger medial orbitofrontal cortical areas, and
