Organic brain syndrome, also known as organic brain disease, organic brain disorder, organic mental syndrome, or organic mental disorder, refers to any syndrome or disorder of mental function whose cause is alleged to be known as organic (physiologic) rather than purely of the mind. These names are older and nearly obsolete general terms from psychiatry, referring to many physical disorders that cause impaired mental function. They are meant to exclude psychiatric disorders (mental disorders). Originally, the term was created to distinguish physical (termed "organic") causes of mental impairment from psychiatric (termed "functional") disorders, but during the era when this distinction was drawn, not enough was known about brain science (including neuroscience, cognitive science, neuropsychology, and mind-brain correlation) for this cause-based classification to be more than educated guesswork labeled with misplaced certainty, which is why it has been deemphasized in current medicine. While mental or behavioural abnormalities related to the dysfunction can be permanent, treating the disease early may prevent permanent damage in addition to fully restoring mental functions. An organic cause to brain dysfunction is suspected when there is no indication of a clearly defined psychiatric or "inorganic" cause, such as a mood disorder. Types Organic brain syndrome can be divided into 2 major subgroups: acute (delirium or acute confusional state) and chronic (dementia). A third entity, encephalopathy (amnestic), denotes a gray zone between delirium and dementia. The Diagnostic and Statistical Manual of Mental Disorders has broken up the diagnoses that once fell under the diagnostic category organic mental disorder into three categories: delirium, dementia, and amnestic. Delirium Delirium or Acute organic brain syndrome is a recently appearing state of mental impairment, as a result of intoxication, drug overdose, infection, pain, and many other physical problems affecting mental status. In medical contexts, "acute" means "of recent onset". As is the case with most acute disease problems, acute organic brain syndrome is often temporary, although this does not guarantee that it will not recur or progress to become chronic, that is, long-term. A more specific medical term for the acute subset of organic brain syndromes is delirium. Thinking, remembering, sleeping, and paying attention can become difficult during alcohol withdrawal, after surgery, or with dementia. Dementia Dementia or chronic organic brain syndrome is long-term. For example, some forms of chronic drug or alcohol dependence can cause organic brain syndrome due to their long-lasting or permanent toxic effects on brain function. Other common