Monomania

Monomania is a mental condition where a person becomes intensely fixated on a single idea, belief, or interest, to the point that it dominates their thoughts and behaviors. While they may function normally in other areas, their focus on this one theme can lead to obsessive patterns, irrationality, or compulsive actions related to that obsession. It is often seen in historical contexts but is not a formal diagnosis in modern psychiatric manuals. Essentially, it reflects a narrow, persistent preoccupation that can impair judgment and social interactions, stemming from an intense, singular mental preoccupation.