This study provides a first look at rates of suicidal thoughts and attempts in individuals with PWS, a population whose common characteristics and comorbidities may increase vulnerability to suicidality. According to a cross-national survey of 84,850 adults across 17 countries, life-time prevalence rates of SI and SA in the general population were 9.2 and 2.7%, respectively . In youth and young adults, the rates of SI and SA reportedly varied from 10.3% (SI) and 3.0% (SA) in a Canadian study  to 18.8% (SI) and 8.9% (SA) in the US . Psychiatric comorbidities and social problems are associated with greater risk of suicide across ages groups and are all commonly present in PWS .
In this natural history investigation of 750 individuals with PWS, the reported lifetime prevalence of SI was 12.5% and SA was 3.3%. We identified several factors associated with a history of SI and SA in persons with PWS, including but not limited to older age, male gender, aggressive behaviors, and mental health problems. Those with reported SI or SA were predominantly adults. Notably in this study, adults with PWS have a higher prevalence of SI (22.8%) compared to rates in the general adult population, whereas youths with PWS appear to have lower rates of SI (7.7%) compared to the general population of children and adolescents. Along with having a longer period of time to experience and report suicidality, adults may also experience higher rates of SI due to reduced support after aging out of the school system. The functional status “not in school or employed” was significantly associated with reported SI in this registry (Table 2). This result highlights importance of suicidality screening and interventions especially for adults with PWS.
In this analysis comparing groups with and without a history of suicidal thoughts, individuals with reported SI were more likely to be male. This differs from general population studies in which female gender has been associated with greater SI, and male gender with higher rates of death by suicide . In students, female gender was associated with higher prevalence estimates of both SI (24.1%) and SA (11%). Replication is needed to confirm the results from this study.
We had hypothesized that genetic subtype would be associated with greater rates of suicidality, but there was no significant relationship found in this study. We also hypothesized that more robust emotional/social connection (as reflected by the presence of a best friend) and financial resources (as evidenced by gross annual income) would be associated with lower rates of SI. This was not shown in our analysis, indicating that these factors should not dissuade from screening for SI.
In line with the previous reports [12, 27,28,29], high rates of behavioral and psychiatric comorbidity were reported in this sample (Table 3). As in general population research, in this collection of individuals with PWS, those with a reported history of SI were more likely to have depression, anxiety, bipolar disorder, or psychosis and more likely to be receiving therapeutic or pharmacologic mental health treatments. This study did not evaluate a prevalence or association of SI with trauma-related disorders, personality disorders, or eating disorders, all of which have shown association with suicide in other populations. A history of aggressive behaviors was also significantly associated with a history of suicidal thoughts, suggesting that this could be an important risk factor. Common self-injurious behaviors in PWS, such as skin-picking, don’t necessarily reflect intent to cause self-harm; this may explain how their presence in this population was not significantly associated with reported SI. Notably, the absence of any SIB appears reassuring. Investigating psychiatric family history may also be beneficial when assessing suicide risk in a person with PWS, as this was significantly more common in the group with Reported SI.
This study has several limitations. It evaluated data from a community-based sample rather than information collected at points of medical care. Data was also primarily per caregiver report rather than direct subject screening, which may limit comparison to estimates of SI and SA prevalence in other studies. As described in the Methods section above, data was also collected by the registry on a rolling basis and at different points in time. Given the significant variability among individuals with intellectual developmental disability (IDD), it is also difficult to compare our findings to other IDD populations, especially as our data did not include information about subject intellectual functioning and this can vary greatly among persons with PWS. In addition, the social and demographic makeup of our study sample should be considered when generalizing about PWS as a whole. Finally, while this study is useful as a first reflection of SI in PWS, we did not have complete data about level of intent, planning, severity, or other details of suicidality or SIB.
Suicide may be prevented with effective screening and appropriate support. Given the considerable rates of suicidal thoughts and attempts in PWS, professionals working with PWS should strongly consider screening for SI with these individuals and their caregivers. Identifying an appropriate screening method for suicidality in different levels of intellectual disability may be a challenge, however the valuable information gathered here from one broad question in the Global PWS Registry suggests that even a general suicide risk screening tool such as Ask Suicide screening Questions (ASQ, https://www.nimh.nih.gov/research/research-conducted-at-nimh/asq-toolkit-materials/) could still be meaningful. Additionally, given the close involvement of caregivers in the lives of many people with PWS, caregiver psychoeducation and screening could be considered as a potential intervention.
When considering next steps for addressing suicidality in individuals with PWS, it would be helpful to take a closer look at SI and SA with specific levels of intellectual disability and with a broader range of psychiatric comorbidities. Direct subject assessment of randomly selected individuals from the Global PWS Registry would also be a step toward better understanding the risks for and life experiences of those with PWS.