Perseveration. Part I: a review.

Perseveration refers to the inappropriate continuation or repetition of a response or activity. It is associated with a variety of neurological disorders and, when pronounced, is thought to be pathognomonic of brain damage. Perseveration manifests itself in several different forms which have had various labels applied, and many hypotheses have been proposed to explain the mechanisms underlying these perseverative behaviours. In this article we review descriptions and classifications of perseveration as it occurs in various neurological disorders, and then discuss some of the neurobehavioural and neuropathological mechanisms thought to account for it.