Therapies for Down Syndrome Regression Disorder

Recent published case reports and clinical experience of the investigators indicate Down Syndrome Regression Disorder (DSRD) may be successfully treated with immune-modulating therapies, in addition to current pharmacologic options. This study is a multidimensional clinical trial designed to advance the understanding of the etiology of DSRD and to evaluate the safety and efficacy of three distinct therapeutic approaches to treating DSRD: (1) the benzodiazepine lorazepam (Ativan™) (2) intravenous immunoglobulin (IVIG, Gammagard™) or (3) the JAK inhibitor tofacitinib (Xeljanz™). Participants will be randomized into one of the three treatment arms above for the 12-week study period, with a subset of participants undergoing an initial 12-week observational period. Specific Aims: 1. To define the relative safety profile of lorazepam, IVIG, and tofacitinib in DSRD. 2. To compare the efficacy of lorazepam, IVIG, and tofacitinib in DSRD. 3. To investigate potential mechanisms underlying DSRD and its response to therapies.