A method of establishing a brain status indication parameter indicative of a brain disorder is disclosed. The method comprising the steps: - determining a brain energy metabolism indicator of at least a part of the brain of a subject, - determining a skull energy metabolism indicator of at least a part of the skull of said subject, - establishing the brain status indication parameter by at least relating said brain energy metabolism indicator to said skull energy metabolism indicator. Also disclosed are a system for establishing such brain status indication parameter, a computer program, and methods for treating a disease.