What is an organic mental disorder and chronic brain syndrome?

OBS: Both are same, & indicate a decrease in mental functioning due to medical/physical illness. It can be acute (delirium), subacute (encephalopathy), or chronic (dementia).

Jogs my memory: Haven't heard those terms for years, and they refer to brain pathology in a generic and vague sense reflecting lack of understanding of different neurological conditions and ability to diagnose. These terms are now meaningless, and only a historical semantic relic.

Terminology: These are older terms intending to contrast disorders affecting physical brain & its anatomical functioning, with disorders thought to be more neurotic -- arising from unconscious defense mechanisms at the like. "organic mental disorders" include acute confusional states like delirium, as in alcohol & drug withdrawal. They also include chronic syndromes such as dementia (example: alzheimer's).