Phase I Baseline study (4 months). A baseline investigation will be conducted to establish the prevalence, duration and type of delirium symptoms in patients with acute acquired brain injury. Usual care will be provided at this time. For validation a psychiatric team will rate included patients usingThe Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) and The International Classification of Diseases (ICD-10) as the gold standard. The psychiatric team assesses patients the first and second day after the patient has a RASS -2 or above for 24 hours.