Parkinson's Disease

Parkinson's is a neurodegenerative disorder caused by decreased production of dopamine from the substantia nigra resulting from destruction of dopaminergic neurons.  Clinically, this disorder is characterized by muscular rigidity, tremors, abnormal gait, slowed movements (bradykinesia), and change in posture.  Patients with Parkinson's can also have non-motor symptoms including dysautonomia, hallucinations and cognitive decline.  The root cause of Parkinson's is not known.  Parkinson's generally affects patients >65 years old.  

The substantia nigra is responsible for providing inhibition to the neostriatum via dopamine release.  The neostriatum is an important part of motor control in the body.  In the absence of dopamine inhibition from the substantia nigra, the neostriatum releases larger amounts of acetylcholine.  This increased release of acetylcholine causes imbalances in the motor control that patients with Parkinson's exhibit.  

The primary goals of treatment for Parkinson's disease is to return the appropriate balance of acetylcholine and dopamine effects.

Most drugs used to treat Parkinson's focus on increasing dopamine effects. Categories of these medications include:

• Levodopa/Carbidopa

• MAO Type B Inhibitors

• COMT Inhibitors

• Ergot Dopamine Receptor Agonists

• Non-Ergot Dopamine Receptor Agonists

• NMDA Receptor Antagonists

Antimuscarinic drugs are also used to treat Parkinson's disease but are not as effective.  These drugs focus on inhibiting the effects of increased acetylcholine levels:

• Antimuscarinic Drugs