The aim of this study is to evaluate the utility of continuous Holter ECG recording with automated, computerized data analysis for measuring antipsychotic-related QTc prolongation during a 24-h period under clinical conditions

Inclusion Criteria:

1. Subjects will be males or females between 18 - 65 years of age.
2. Patient subjects will have a definite diagnosis by DSM-IV criteria, schizophrenia, schizoaffective disorder, or bipolar disorder.
3. Patient subjects are currently under treatment with any antipsychotic, any mood stabilizer, any antidepressant or any combination of the above at the therapeutic dose for at least 3 months.
4. Patients have a history of taking the medications listed in item 3 as prescribed.
5. The subjects must be able to provide written informed consent

Exclusion Criteria:

1. Subjects with a DSM-IV diagnosis of substance dependence as defined by DSMN within three months prior to selection.

2. Subjects who are currently taking other medications that have been shown to prolong the QTc, including tricyclic antidepressants (e.g. amitriptyline, imipramine, maprotiline), fluoroquinolones, or antiarrhythmics (e.g. quinidine, procainamide, amiodarone, sotalol).

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