Comorbidity of schizophrenia and adult attention-deficit hyperactivity disorder

Adult ADHD is characterised by a plethora of comorbid conditions. However, the comorbidity of schizophrenia and ADHD does not seem to be a typical feature and is therefore under-researched.To identify adult patients with schizophrenia and comorbid ADHD and compare their symptomatology with schizophrenic patients without ADHD.Performance in specific neuropsychological tests (set shifting, selective and sustained attention, cognitive performance, and speed of information processing) was determined. Additionally, important demographic data and information about the patients' history such as the number of suicide attempts were gathered. Twenty-seven patients were involved in this study (14 male and 13 female). Fifteen patients were diagnosed with schizophrenia/no ADHD and twelve had both schizophrenia/ADHD.We report here an increase in suicidal behaviour of patients with both schizophrenia and ADHD compared to schizophrenia only. A significant underperformance of the patients with ADHD comorbidity compared to patients with schizophrenia only was also determined.The increased suicidal behaviour in patients with schizophrenia and ADHD suggests the need of further studies on mood regulation and suicidal ideations in these patients.