SAM-e for the Treatment of Depression in Patients With Parkinson's Disease

Inclusion Criteria * Idiopathic Parkinson's disease as indicated by the presence of at least two of the following signs: resting tremor, rigidity, bradykinesia, or postural reflex impairment * Stable anti-parkinson medication regimen, with no change in medications in the 4 weeks prior to study entry * No antidepressant or antipsychotic medications within 30 days prior to study entry * Agree not to start other pharmacotherapy, psychotherapy, or behavior therapy while participating in the trial * Acceptable methods of contraception * Ability to read and/or follow written and oral instructions presented in English * Sufficient cognitive ability (baseline Mini-Mental Status \> 24) to provide informed consent Exclusion Criteria * History of cardiac, hepatic, renal, hematologic, respiratory, endocrine, vascular, metabolic, or other systems abnormalities that are clinically relevant in the opinion of study officials * Certain abnormal laboratory values * Pregnant or breastfeeding * Use of an investigational drug within 3 months of study entry * Use of St. John's Wort or any other "natural" product known to have mood enhancing properties in the 30 days prior to study entry * Selegiline or other monoamine oxidase inhibitor within the 6 weeks prior to study entry * Regular usage of anti-anxiety medications or habitual use of sleep medications, although occasional use of certain hypnotics (temazepam, melatonin, or zolpidem) is allowed * Psychotherapy initiated in the 6 months prior to study entry * History of bipolar disorder, hypomania, mania, schizophrenia, or other psychotic disorder * Serious suicidal attempt in the 12 months prior to study entry or serious suicidal tendencies/potential * Use of dopamine receptor antagonist (metoclopramide, haloperidol) * Secondary Parkinsonian symptoms due to drugs (including dopamine receptor antagonists), metabolic disorders, cerebrovascular disease, encephalitis, or other degenerative diseases