M76. ATYPICAL RESPONSE INHIBITION IN 22Q11.2DS: DIMINISHED ERROR REGISTRATION AND AWARENESS

Background 22q11.2 deletion syndrome (22q11.2DS; also known as DiGeorge syndrome or velo-cardio-facial syndrome) is characterized by increased vulnerability for neuropsychiatric symptoms, with approximately 30% of the individuals with the deletion developing schizophrenia. Clinically, deficits in executive function have been noted in this population, but the underlying neural processes are not well understood. Methods Using high-density electrophysiology (EEG), we investigated the neural dynamics of inhibition of a prepotent response (a critical component of executive function) in individuals with 22q11.2DS with and without psychotic symptoms. Twenty-seven individuals with 22q11.2DS (14–35 years old, 14 with at least one psychotic symptom) and 27 age-matched neurotypical controls participated in a go/no-go task while EEG was recorded. Analyses were focused on the P3 go/no-go response and error-related positivity (Pe). Results Behaviorally, individuals with 22q11.2DS were slower and unable to inhibit prepotent responses as the controls, with significantly more false alarms. Atypical inhibitory processing was confirmed by significantly reduced P3 no-go responses in the 22q11.2DS group. Such reductions were particularly marked in those with psychotic symptomatology. Pe was likewise significantly decreased (regardless of the presence of psychotic symptoms), suggesting impaired ability to register errors (i.e., false alarms) in 22q11.2DS. Both Pe and P3 correlated with clinical measures of inhibition (DKEFS and CPT). Discussion To our knowledge, this is the first study looking at electrophysiological measures of response inhibition in 22q11.2DS. P3 and Pe reductions, which have also been shown in schizophrenia, suggest diminished error registration and awareness in 22q11.2DS and, possibly, a consequent difficulty in adjusting response strategies.