The psychiatric and behavioural characteristics of individuals with 22q11.2 deletion syndrome (22q11DS): An Irish population study

Abstract

Background: There is a growingbody of evidence which indicates an unequivocal association between 22qllDS and schizophrenia. Deletion of 22qll is recognised as the third highest risk for the development of schizophrenia, with only a greater risk conferred by being the child of 2 parents with schizophrenia or the monozygotic co-twin of an affected individual. The challenge for clinicians and researchers is to identify early vulnerability traits, symptoms or disorders which may be associated with or predict a later emerging psychotic disorder, so that at risk individuals maybe identified, monitored and treated early to improve outcomes. Identification of these early traits or symptoms firstly requires detailed analysis of the behavioural phenotype in individuals with 22qllDS. The current study aims to define the prevalence and correlates of psychiatric disorders in a population cohort of individuals with 22qllDS in Ireland. The data gained from the study will provide the foundation for future longitudinal studies of risk factors of psychosis in 22qllDS. Methods: Forty-five individuals with 22qllDS (mean age = 14.6, SD 8.94) and 27 sibling controls (mean age = 12.2, SD 4.12) participated in the study. The rate of psychiatric and behavioural disorders was investigated through a range of semi-structured interviews and standardised questionnaires. This is the first study to use the Comprehensive Assessment of at Risk Mental State (CAARMS), a tool which has been designed to identify a possible prodromal state. Results: Individuals with 22qllDS had high rates of psychiatric disorders and had significant difficulties with social and school functioning (p < 0.0001) compared to sibling controls. The most frequently occurring were attention deficit hyperactivity disorders (29%, p = 0.001) and anxiety disorders (31%, p = 0.021). Eight individuals (18%) with 22qllDS exhibited subthreshold psychotic symptoms (mean age = 13, SD 2.8, range 7–16 years) and had significantly higher rates of co-morbid psychiatric disorders (p = 0.0003), were found to be more irritable/confrontational with peers/siblings (p = 0.0002), disorganised (p = 0.0001), more likely to be clumsy with coordination difficulties (p < 0.001) and had peer problems (p = 0.01) compared to individuals with the deletion and without subthreshold psychotic symptoms. No significant association was found between FSIQ and subthreshold psychotic symptoms (p > 0.05). Conclusion: Children and adolescents with 22qllDS and subthreshold psychotic symptoms were found to be more irritable, disorganised, and clumsy and have peer-related problems. These symptoms may identify individuals who may be at risk for a later emerging psychotic disorder and who may require careful monitoring and follow-up.