Akathisia is a relatively common side effect of neuroleptic medication that occurs within 1 week to 6 months after the initiation of medication. Akathisia is characterized by a variety of movement manifestations, such as fidgeting, irritability, inability to sit or stand still, marching in place, continuous trunk motions, sleeplessness, and a subjective sense of restlessness. Akathisia has been studied primarily in schizophrenic patients, although reports on individuals with mental retardation suggest that akathisia also occurs in this population. This study will characterize the movement dynamics of akathisia in schizophrenic and mentally retarded adults using two experimental series.

The first experimental series will compare chronic akathisia in schizophrenic and MR patients. Four groups of MR patients and four groups of schizophrenic patients will be studied: young (age 18 to 38) with chronic akathisia, older (age 40 to 60) with chronic akathisia, young on neuroleptics without akathisia, and older on neuroleptics without akathisia. Two control groups will include healthy individuals with normal intelligence who are not on neuroleptic medication. Assessments will include videotaped recordings and kinematic analysis of naturally occurring akathisia restlessness movements as well as cognitive and psychiatric tests. Demographic factors (age and sex) and medication factors (type and duration) will also be assessed to determine their relation to and possible impact on chronic akathisia.

The second experimental series will compare schizophrenic and MR patients who are initiating neuroleptic therapy. Institutionalized MR patients will be age matched with schizophrenic patients. Tests will occur at baseline (prior to drug initiation) and at Weeks 1, 2, 4, 8, 16, 24, and 52. Those who enroll in the protocol early will be tested for more than 12 months where possible and useful. The same analyses as in the first experimental series will be used to allow for comparison of acute and chronic akathisia.

Inclusion Criteria for Experimental Series I

• Chronic akathisia for at least 3 months prior to study entry
• Neuroleptic medication for at least 6 months prior to study entry (anticonvulsant medication will be accepted and those on carbamazepine and ethosuximide will be monitored for the development of akathisia)
• Mental retardation/developmental delay diagnosis based on American Association of Mental Deficiency definition or diagnosis of schizophrenia based on the DSM-IV criteria

Inclusion Criteria for Control Group

• Control groups will be matched to akathisia groups based on age and level of disability (IQ for mental retardation population, BPRS positive symptoms of schizophrenia for schizophrenic groups).

Exclusion Criteria

• Psychotropic drugs such as serotonin re-uptake inhibiting anti-depressants
• Nonambulatory
• Uncontrolled seizure disorders
• Fragile X syndrome
• Down Syndrome
• Neurological disease that is known to have definitive symptoms of choreoathetosis, dystonia, Syndenham's chorea, etc.