Antipsychotics are also known as neuroleptics and major tranquilizers. They have been shown to be very effective in reducing psychotic symptoms and are most frequently prescribed for the treatment of schizophrenia. They are also used to treat acute mania, and delusions and hallucinations associated with other disorders such as depression and organic psychoses. Research findings have indicated that antipsychotic drugs seem to work by blocking dopamine receptors in the brain, although the findings are equivocal. There are a number of side effects associated with antipsychotics (e.g. drowsiness, very dry mouth, constipation, tremors), and these start early. Tardive dyskinesia, which includes symptoms such as involuntary rhythmic movements, is one of the most serious side effects and is more common in elderly patients. The symptoms of tardive dyskinesia are reversible if discovered early and the patient is taken off these medications. Use of antipsychotics is generally believed not to create tolerance (aside from some side effects), psychological or physiological dependence.