Trial of OnabotulinumtoxinA for Depression in Parkinson Disease

This study evaluates the efficacy of onabotulinumtoxinA (BOTOX®) in the treatment of depression associated with Idiopathic Parkinson Disease in adults. As a Randomized Controlled Trial, half of the participants will receive onabotulinumtoxinA injections and half will receive a placebo saline solution.

Depression is a common, but treatable, comorbid condition often seen in persons with Idiopathic Parkinson Disease (iPD). Depression in Parkinson Disease may be hard to treat as patients with iPD may be sensitive to side effect of medication. As a result, other treatments which have better side effects profiles than antidepressants may be equivalent (or better) options.

OnabotulinumtoxinA is a purified formulation of botulinum toxin serotype A which is widely utilized for neurological (and cosmetic) purposes in medicine. OnabotulinumtoxinA has preliminary studies showing it may be beneficial for the treatment of Major Depressive Disorder when given in isolated injections to facial muscles (corrugator and procerus). When given in low doses, onabotulinumtoxinA is thought to have minimal side effects.

The investigators propose that a single treatment onabotulinumtoxinA may improve symptoms of depression in persons with Parkinson Disease over three months compared to placebo. The investigators plan to use both subjective and objective evaluations of depression symptoms and regular physical exams to ensure physical (motor) symptoms of Parkinson Disease do not worsen.

Eligibility Criteria:
Inclusion Criteria:

* Written informed consent is obtained in the English language;
* They are a 18 to 95 years old;
* They meet United Kingdom Brain Bank Criteria for probable idiopathic Parkinson disease;
* They meet Diagnostic and Statistical Manual (DSM)-IV criteria for major depressive disorder (MDD) as diagnosed by the M.I.N.I. at screening;
* They are judged by the investigator to have the capacity to understand the nature of the study;
* They are willing to comply with all the requirements of the study;
* They are considered by the investigator to be likely to adhere to the protocol.

Exclusion Criteria:

* They have been treated with onabotulinumtoxinA injected into the facial muscles for any reason in the 3 months prior to screening;
* They have Bipolar Disorder, Post-Traumatic Stress Disorder, a Psychotic Disorder or any other non-unipolar depressive disorder as a principal diagnosis in the 6 months prior to screening;
* They endorse active suicidal ideation at enrollment or during any study visit, or have attempted suicide in the six months prior to screening;
* They have a history of substance abuse or dependence in the 2 months prior to screening;
* They test positive for illicit drugs on urine screen, and this has not been adequately explained to the satisfaction of the investigator
* They are considered to be at significant risk of committing homicide;
* They have an unstable medical condition;
* Women of childbearing potential who are pregnant or are considering becoming pregnant during the length of the study;
* There has been a change in their PD medication or psychotherapy treatment regimen in the 30 days preceding screening;
* They are regarded, for any reason, by the principal investigator as being an unsuitable candidate for the protocol.