Post-traumatic stress disorder (PTSD) is prevalent amongst civilians in our society. The factors most commonly associated with developing PTSD are female gender and recent exposure to sexual abuse (Knipscheer et al., 2020).Globally, it is estimated that nearly 1 out of every 3 women have experienced either physical or sexual abuse (Organization, 2013). Amongst survivors of rape 1 out of 2 report being raped by their intimate partner and just over 40% reported being raped by an acquaintance (Breiding, 2014). Moreover, over 80% of women report the first experience of rape prior to turning 25 years (Smith et al., 2018). The literature supports that following sexual trauma over 90% of these women will experience symptoms of post-traumatic stress within two weeks of the event (Rothbaum, Foa, Riggs, Murdock, & Walsh, 1992). Moreover, 30% will report symptoms after nine months (Davidson & Foa, 1993). If left unresolved these symptoms may persist for years, negatively impacting mind and body. Despite the prevalence of sexual trauma in women neuropsychiatric research has nearly exclusively focused upon survivors formally diagnosed with PTSD.
Although not all sexual abuse survivors develop PTSD, experiencing a traumatic event can be extremely stressful. Traditionally, experiencing sexual trauma, regardless of PTSD diagnosis, is associated with negative neurocognitive outcomes as a function of neuroendocrine and neuroinflammatory dysregulation (Sapolsky, Krey, & McEwen, 1986; Swaab et al., 1994). In a 35-year follow-up study, it was found that females who reported constant stress in their lives were more likely to develop dementia and Alzheimer’s disease (Johansson et al., 2010). When compared to undiagnosed sexual abuse survivors, those formally diagnosed with PTSD show a higher prevalence of dementia in older age (Flatt, Gilsanz, Quesenberry Jr, Albers, & Whitmer, 2018; Qureshi et al., 2011). Despite this, deficits in the verbal memory and processing speed are observed in sexual abuse survivors not diagnosed with PTSD (Forest & Blanchette, 2018; Petkus, Lenze, Butters, Twamley, & Wetherell, 2018).
Our study focused on two brain regions commonly implicated in fear-associated learning in those diagnosed with PTSD, i.e., the amygdala and hippocampus (Maren, Phan, & Liberzon, 2013). Resting state functional connectivity (rsFC), an index of synchronous neural activity, between the hippocampus and amygdala are associated with the severity of PTSD symptoms (Rabinak et al., 2011). Furthermore, lower rsFC of the hippocampus predicts episodic memory deficits (Touroutoglou, Andreano, Barrett, & Dickerson, 2015) and risk for developing Alzheimer’s disease (Allen et al., 2007). These aberrant patterns of brain activity might be explained by the effect of post-traumatic stress on cortisol output. Although elevated peripheral cortisol is observed upon initiation of a traumatic experience, these levels commonly reside and remain deficient following the trauma due to a negative feedback mechanism along the hypothalamic-pituitary-adrenal axis. Critically, elevations in cortisol enhance memory consolidation, whereas deficits are concomitant with decreased hippocampal and amygdala activity during memory consolidation (Henckens et al., 2012; Henckens, van Wingen, Joëls, & Fernández, 2010). In our study, levels of post-traumatic stress were correlated with lower verbal memory recall and functional connectivity between the dentate gyrus of the hippocampus and central nucleus of the amygdala.
As noted earlier, sexual abuse survivors, regardless of PTSD diagnosis, suffer cognitive impairments when compared to healthy controls. These impairments prevail through verbal recall deficits and may even result in an increased risk of Alzheimer’s or dementia through mechanisms such as an increased cortisol release, reduced hippocampal volume, and reduced hippocampal-amygdala rsFC. Given the large incidence of sexual abuse world-wide, it is important to bring attention to this issue when studying the cognitive effects of trauma survivors and further research should be allocated to studying the cognitive effects of sexual abuse.
Target Article
McIntosh, R., Lobo, J., Carvalho, N., Ironson, G. (2022). Learning to forget: Hippocampal–amygdala connectivity partially mediates the effect of sexual trauma severity on verbal recall in older women undiagnosed with posttraumatic stress disorder, Journal of Traumatic Stress.
Discussion Questions
- Are trauma survivors not diagnosed with PTSD still at risk for trauma-associated neurocognitive impairment?
- Is altered hippocampal-amygdala connectivity a feature in trauma-exposed persons at greater risk for Alzheimer’s disease, dementia, and verbal memory impairment?
- Might trauma interventions mitigate the rate of cognitive decline and restore functional brain connectivity in trauma-exposed individuals?
About the Authors
Roger McIntosh, Ph.D., is an Associate Professor of Health Psychology and Cognitive Behavioral Neuroscience at the University of Miami. His work focuses on the psychosocial determinants of health in vulnerable populations such as women living with HIV.
Sally Dahan B.S., is a Psychology and Health Science from the University of Miami. She is currently a volunteer research assistant in the BREATH Laboratory.
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