Individuals with intellectual disability (ID) are more vulnerable to psychotic disorder and schizophrenia than the general population. However, psychotic symptoms have not been widely described in this population. Here, we deeply investigated the cases of two young women with ID and Down syndrome (DS) who developed a delusion of pregnancy, a rare condition defined as a fixed belief of being pregnant despite factual evidence to the contrary. The assessment included psychopathological and neuropsychological examination, as well as the evaluation of cognitive and adaptive functioning. In these cases, delusion manifested as a psychotic symptom of a cyclothymic disorder (case 1) or as an independent delusional disorder (case 2). However, some similarities emerged: both women exhibited good pre-morbid adaptive functioning and family history of psychiatric disorders; moreover, in both cases delusion emerged in association with an external trigger. Difficulties in verbally expressing one's thoughts and beliefs were found, as well as poor abstract reasoning skills that may have affected the ability to deeply conceptualize the delusional idea itself. These findings may provide crucial insights into the clinical manifestation of psychosis in individuals with DS and underscore the importance of a routine psychological and neuropsychological follow-up to provide prompt and adequate intervention.
Keywords: intellectual disability; psychiatric disorders; psychosis; trisomy 21.