Enhanced memory function and reduced perceived stress in older adults with self-reported memory complaints following strawberry leaf extract supplementation: a randomized, double-blind, placebo-contro

Posttraumatic stress disorder (PTSD) is among the most debilitating mental health conditions worldwide, contributing to elevated demand for clinical services and substantial economic costs (). PTSD can persist for years following trauma exposure (; ; ; Solomon & Mikulincer, 2009), and many individuals continue to meet diagnostic criteria even after completing evidence-based treatments (; ). Beyond hallmark symptoms of re-experiencing, avoidance, emotional numbing, and hyperarousal, PTSD is characterized by a heightened sensitivity to environmental unpredictability (; ). In daily life, trauma-exposed individuals often struggle with ambiguous or uncontrollable situations (e.g. awaiting uncertain outcomes or interpreting unclear interpersonal cues) that sustain a sense of threat even in objectively safe contexts. Cognitive models propose that PTSD endures when trauma is processed in ways that leave individuals uncertain about their safety and maintain a sense of constant danger (; ). More contemporary predictive-processing models likewise conceptualize PTSD as a disorder of uncertainty calibration, wherein exaggerated threat expectations overpower actual sensory information, preventing adaptive belief updating and reinforcing hypervigilant states (). Additionally, maladaptive behavioral and cognitive strategies aimed at reducing uncertainty, such as avoidance (), thought suppression (), rumination (), and safety behaviors (Helbig-Lang et al., 2010), mirror the very processes proposed to maintain PTSD. Overall, these theoretical accounts suggest that individuals with PTSD misestimate uncertainty () and exhibit an exaggerated anticipatory bias towards threat uncertainty (), contributing to an intolerance of uncertainty (IU) that may present as both a trait-like vulnerability and state-dependent process. Consequently, investigating individual differences in IU may be crucial in explaining fluctuations in PTSD symptom severity. IU describes an individual’s reduced tolerance for negative affect produced by perceived uncertainty or lack of information (). It reflects a fundamental fear of the unknown, described as the “most basic component of pathological anxiety” (), which characterizes anxiety disorders and extends to PTSD. Individuals high in IU experience the possibility of a negative event as unacceptable and threatening, irrespective of its likelihood (), thereby perpetuating the hallmark PTSD appraisal that “the danger is not over.”