First stage of the Kangoroo Method: adaptation of mothers of premature newborns to Roy's light.

Post-traumatic stress disorder (PTSD) is a chronic, debilitating psychiatric illness that develops following exposure to a traumatic event. Those suffering from PTSD exhibit symptoms such as involuntary re-experiencing of the trauma (flashbacks) and actively avoid reminders of the trauma []. In 2013, the World Health Organization (WHO) estimated that 3.6% of the world’s population had suffered from PTSD [], making it a moderately common and widespread disorder. A study combined data from the WHO World Mental Health Surveys in 24 countries worldwide and found that 70.4% of participants experienced at least one traumatic event in their lifetime, with 30.5% exposed to four or more events []. Follow-up analysis of the surveys corroborates the lifetime prevalence of PTSD in ∼4% of the total respondents (∼5.6% of trauma-exposed respondents) [, ]. The majority of people will experience some form of trauma, yet not everyone exposed will develop persistent symptoms. The effects of PTSD can harm an individual’s health, increasing the risk of comorbid disorders and potentially leading to suicide []. It can also be a burden to the economy through lost productivity and be expensive for the individual and their loved ones seeking treatment [, ]. Therefore, it is crucial to understand who is at greater risk of developing PTSD and how to treat patients with PTSD effectively. This has prompted further research into the neurobiological mechanisms behind PTSD to identify predisposing factors. Ultimately, the goal is to find biomarkers for predicting PTSD susceptibility and to develop more effective therapies or treatments. Recent studies have explored epigenetic modifications (such as DNA methylation and histone acetylation) as potential biological processes involved in PTSD pathophysiology []. In particular, microRNAs (miRNAs), a type of small noncoding RNAs, have recently gained significant attention for their role in various psychiatric disorders, including schizophrenia, bipolar disorder, major depressive disorder, and PTSD []. They can widely influence the expression of multiple coding genes after transcription. The dysregulation of any single miRNA can affect numerous signaling pathways, contributing to the overall disease process []. With this review, we seek to comprehensively assess the current state of miRNA research as it relates to PTSD, integrating evidence across molecular, behavioral, and translational domains. Our goal is to examine miRNAs within the broader neurobiological framework of PTSD, highlighting how these small noncoding RNAs contribute to vulnerability, symptom persistence, and the diverse physiological alterations observed following trauma. To establish this foundation, we first provide an overview of the key features of PTSD, including its diagnostic criteria, heterogeneous clinical presentation, and documented neurobiological abnormalities. We also present a concise description of miRNA biosynthesis and function, outlining the major steps of their biogenesis, and emphasizing how individual miRNAs can regulate extensive gene networks through post-transcriptional repression. Following this conceptual groundwork, we summarize findings from recent empirical studies examining miRNA regulation in PTSD using both animal models and human patient samples. These investigations span a wide array of methodological approaches, including fear-conditioning paradigms, acute and chronic stress models, analysis of peripheral tissues, and emerging work on extracellular vesicles (EVs). By comparing convergent themes across species and experimental contexts, we highlight key miRNAs implicated in synaptic plasticity, hypothalamic–pituitary–adrenal (HPA) axis regulation, inflammatory signaling, and trauma-related memory processes. Particular attention is given to miRNAs targeting FKBP5, stress-responsive transcription factors, and inflammatory cytokines, as these molecules represent some of the most consistently dysregulated pathways across the current literature. Altogether, this review aims to synthesize diverse lines of evidence to elucidate the significance of miRNAs in PTSD pathophysiology. By critically evaluating the strengths and limitations of existing research, we also identify knowledge gaps and propose future directions to advance the field. These include longitudinal assessments, deeper integration of central and peripheral measures, and translational efforts that may ultimately support the development of miRNA-based biomarkers or therapeutic targets.