A rat model for attention deficit-hyperactivity disorder.

A number of animal models for attention deficient-hyperactivity disorder (ADHD), a common childhood disorder, have been developed. However, none of these models are truly representative of naturally occurring developmental ADHD. In such models, hyperactivity is induced by electrical or chemical brain lesions, by pharmacological manipulation, or by genetic breeding that is coupled with hypertension. Based on the observation that some hyposexual rats also are hyperactive, we have studied these rats in order to determine whether they portray characteristics representative of ADHD. Results of open field testing, response to stimulant medication challenge, and measurement of the rat's ability to block irrelevant information in a conditioned avoidance response demonstrate three properties characteristic of ADHD: a) a high level of spontaneous motor activity; b) an attenuation of motor activity in response to amphetamine; and c) a deficit in selective attention. These data indicate that these rats may be a model for the study of ADHD.