"Acute Mental Confusion" is used interchangeably with Delirium^[3] in International Statistical Classification of Diseases and Related Health Problems and Medical Subject Headings to describe a pathological degree in which it usually refers to loss of orientation (ability to place oneself correctly in the world by time,^[4] location,^[4] and/or personal identity^[4]) sometimes accompanied by disordered consciousness^[4] and often memory (ability to correctly recall previous events or learn new material). Confusion as such is not synonymous with inability to focus attention, although severe inability to focus attention can cause, or greatly contribute to, confusion. Together, confusion and inability to focus attention (both of which affect judgment) are the twin symptoms of a loss or lack of normal brain function (mentation).^{[citation needed]} The milder degrees of confusion as pathological symptoms are relative to previous function. Thus (for example) a mathematician confused about manipulation of simple fractions may be showing pathology which would not be diagnosable in a person without training in this area. Thus, as with the case of delirium, the minor degrees of pathological confusion cannot be diagnosed without knowledge of a person's "baseline", or normal, level of mental functioning.^{[citation needed]}