Causes of Down syndrome regression disorder: a scoping review.

Down syndrome regression disorder (DSRD) is characterized by an acute or subacute neurocognitive regression that severely impacts the autonomy and quality of life of individuals with Down syndrome (DS). Despite its growing recognition, understanding of the condition remains limited, particularly regarding its etiology and the factors contributing to its development.

Objective: The aim of this study was to systematically map the available evidence regarding the potential causes of DSRD and the factors that may contribute to its development.

Methods: Following the Joanna Briggs Institute (JBI) methodology for scoping reviews, a comprehensive three-step search strategy was conducted across MEDLINE (PubMed), Embase, Cochrane, and Lilacs. Studies published in any language were considered, with no restrictions on publication date.

Results: In total, 14 studies met the eligibility criteria. The findings consistently point to chronic autoimmunity and immune dysregulation as potential causes of DSRD. Additionally, the contribution of genetic variants associated with the type 1 interferon inflammatory response has been suggested. Finally, the role of psychosocial and environmental stressors was highlighted, as these are considered potential triggers that precede the onset of DSRD manifestations.

Conclusion: The hypothesis that DSRD is a multifactorial condition seems reasonable. Nevertheless, the immune system may play a central role in its development, as the identified causes converge toward a neuroinflammatory process. Furthermore, the contribution of genetic variants associated with the inflammatory response and the role of psychosocial stressors as triggers for DSRD also appear plausible.