What term is used to describe an illness caused by a specific agent that leads to structural changes in the brain?

The term "organic" is used to describe an illness that results from a specific agent causing structural changes in the brain. In the context of behavioral health, organic illnesses are typically rooted in biological or physiological changes, which can often be observed through imaging or pathological examination. Examples of organic illnesses include certain forms of dementia, brain injuries, and neurological disorders, all of which result in tangible changes to the brain's structure and function.

This term contrasts with "psychological," which refers to mental health conditions that may not have a clear biological basis or observable structural changes. "Functional" is used to describe disorders in which patients experience significant distress and impairment, but the cause is not attributable to identifiable organ dysfunction or structural abnormalities. "Cognitive" refers specifically to processes related to knowledge, attention, and memory, and does not inherently imply any structural causes or changes in the brain. Therefore, "organic" accurately captures the essence of the question by emphasizing the connection between specific agents and structural changes in brain tissue.