Early life adversity and white matter microstructural organization - a systematic review

Early life adversity, defined as exposure to stressful events during childhood, is a significant risk factor for the development of psychiatric disorders. Diffusion tensor imaging studies employing tract-based spatial statistics have shown microstructural abnormalities in white matter among individuals exposed to early life adversity; however, robust conclusions are yet to be drawn. This systematic review synthesizes findings of previous tract-based spatial statistics studies to identify the white matter alterations in adult brains exposed to early life adversity, in papers with methodological consistency. The literature search (April 2024) was conducted to identify tract-based spatial statistics studies that compared diffusion metrics between adults exposed to early life adversity and adults not. Embase, Pubmed, and PsycInfo were searched, retrieving 2458 articles. Following deduplication, 1739 titles and/or abstracts were screened. 1699 articles were excluded, and 40 full texts were reviewed. Seven articles, reporting on 764 subjects, met the inclusion criteria and were included in the narrative synthesis. Compared to controls, adults exposed to early life adversity showed lower fractional anisotropy values in white matter tracts of the limbic and visual processing systems, specifically the anterior thalamic radiation, inferior longitudinal fasciculus, corona radiata, uncinate fasciculus, inferior fronto-occipital fasciculus, and cingulum bundle. This systematic review highlights that early life adversity may underlie emotional dysregulation and contribute to an increased risk of psychopathology in later life and explores the potential neurobiological mechanisms that underpin these structural changes. Understanding these associations is crucial for developing targeted interventions aimed at mitigating the long-term impact of early life adversity.