Effectiveness and Safety of Selective Serotonin Reuptake Inhibitors in Individuals with Williams Syndrome

Anxiety and depressive disorders are common in individuals with Williams syndrome (WS), yet data regarding pharmacologic treatment in this population are limited. This study aimed to evaluate the effectiveness and safety of selective serotonin reuptake inhibitors (SSRIs) in individuals with WS treated for anxiety and/or depressive disorders.

We conducted a retrospective chart review of patients with a genetically confirmed diagnosis of WS treated with SSRIs between 2010 and 2025 at a clinic for individuals with WS. Fourteen children and adults (5 males and 9 females; mean age: 23.2 ± 11.9 years) met inclusion criteria, contributing 16 distinct SSRI treatment trials. Illness severity was assessed using the Clinical Global Impressions-Severity (CGI-S) scale at baseline and last follow-up and the Clinical Global Impressions-Improvement (CGI-I) scale.

The CGI-S score decreased significantly from 4.62 ± 0.81 at baseline to 3.06 ± 1.12 at last follow-up (t(15) = 3.83, p = 0.002). Nine of 16 trials (56.2%) were rated as much or very much improved (CGI-I = 1 or 2). The mean duration of SSRI treatment was 3.95 ± 3.91 years (range: 0.75-16). Adverse events were documented in two trials (12.5%), and no treatment discontinuations due to adverse events occurred.

SSRI treatment was effective and well tolerated in individuals with WS. Prospective controlled studies are required.