Trial of OnabotulinumtoxinA for Depression in Parkinson Disease

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.