Stereotypy (psychiatry)

A stereotypy is a continuous, repetitive, purposeless or ritualistic movement, posture, or utterance, found in patients with mental retardation, autism spectrum disorders, tardive dyskinesia, and stereotypic movement disorder. Stereotypies may be simple movements such as body rocking, or complex, such as self-caressing, crossing and uncrossing of legs, and marching in place. Several causes have been hypothesized for stereotypy, and several treatment options are available.

Proposed causes of stereotypy
There are several possible explanations for stereotypy, and different stereotyped behaviors may have different explanations. A popular explanation is stimming, which hypothesizes that a particular stereotyped behavior has a function related to sensory input. Other explanations include hypotheses that stereotypy discharges tension or expresses frustration, that it communicates a need for attention or reinforcement or sensory stimulation, that it is learned or neuropathological or some combination of the two, or that it is normal behavior with no particular explanation needed.

Research is ongoing to determine the cause, or more likely, causes of stereotypic behaviors. Some theories hold that the individual's nervous system is in a state of low arousal, or hyposensitivity, so the brain demands high levels of sensory input. Other theories propose that certain repetitive behaviors can actually provide a calming effect by blocking out the effects of overstimulation from the environment. For hypersensitive people, it may provide a "norming" effect, allowing the person to control a specific part of the world they perceive through their senses, and is thus a soothing behavior. Some autism researchers believe that self-injury behaviors in autistic children may be a form of stereotypy as the child derives pleasure from natural opiates released by the brain but does not experience the pain due to sensory integration dysfunction.

Some professionals who evaluate children with autism refer to some stereotypies as stimming, based on the notion that that the role of these stereotypies is self-stimulation. Stereotypy can involve the various senses, so a repetitive movement may be motivated by visual, auditory, tactile, olfactory, vestibular or taste sensations.

Treatment for stereotypy
Treatment options include replacing the repetitive behavior with a more socially acceptable behavior, exercise, or medications. Where sensory integration dysfunction is involved, sensory integration therapy may be used. When gauaged to be appropriate, some behavioral specialists allow a child to engage in self-stimulatory behavior as positive reinforcement in interventions such as Applied Behavior Analysis.

Stereotypies in animals
Stereotypies have also been reported in non-human animals; for example, pacing behaviors by caged cats in zoos is described as a stereotypy, as are behaviors exhibited by sows in farrowing crates such as rocking back and forth and biting at the bars of the crate.