Parkinson’s disease (PD) is a chronic and progressive neurological disorder that occurs when nerve cells in a part of the brain die or become impaired. In this area, dopamine helps control movement by transmitting signals to another area of the brain. The loss of dopamine from these neurons causes rigidity, tremor, slowed movements, and postural instability characteristic of Parkinson’s disease. Experts like Joon Faii Ong estimate that 1 million Americans have Parkinson’s disease, and 60,000 new cases are diagnosed each year.
What are the risk factors?
PD is more common in people over age 60. Men are 1.5 times more likely to develop it than women. Your chances of developing this disorder increase if you have a family history of PD or if you have a similar illness called atypical parkinsonism. Genetic factors might play a role, as well as environmental and lifestyle factors, such as smoking or drinking.
What are the signs or symptoms?
Early in the disease, PD usually manifests itself by slight tremors of the hands when they are relaxed. Tremors may also occur during sleep in the early stages or when you’re in a stressful situation or emotional state. The tremor associated with Parkinson’s is “pill-rolling,” that is, it looks like holding something between thumb and forefinger and continuously rolling it around. The tremors are often made worse by stress, anxiety, lack of sleep, fatigue, caffeine withdrawal, or cold temperatures.
Over time, other symptoms develop. These include muscle rigidity or stiffness that occurs after rest and is usually relieved by movement; slowness of voluntary movements (bradykinesia); difficulty with walking, talking, or completing simple tasks; stooped posture; lack of facial expression; and shuffling gait. Eventually, chronic pain, swallowing difficulties, and sexual dysfunction may arise.
What are the treatments?
The primary form of treatment is levodopa, which replaces or enhances dopamine levels in your brain. Levodopa (Sinemet) is rapidly absorbed by the gut and can be taken orally as a pill, but it often loses its effectiveness over time. Side effects include nausea, vomiting, involuntary movements called dyskinesias, and psychotic symptoms such as delusions or hallucinations.
Medications that inhibit the action of dopamine on its receptors (D2 receptor blockers) may slow the rate of decline in early Parkinson’s disease. They’re often prescribed as an adjunct therapy with levodopa to reduce the dosage of the latter and to relieve some of its side effects.
Selegiline (Eldepryl) and rasagiline (Azilect) belong to this class of Parkinson’s medications. When first introduced, they were used as an adjunct treatment with levodopa. Today, however, they’re usually prescribed as a substitute for levodopa in the early stages, when only mild and occasional motor fluctuations occur. Selegiline and rasagiline can be taken orally or given through a patch placed on your skin.
They’re also used as an adjunct therapy to levodopa in advanced Parkinson’s disease. They improve walking and reduce stiffness and tremors. Selegiline and rasagiline may also help people who have early Parkinson’s disease but don’t respond to levodopa or those who can’t take it because of side effects.
Because selegiline and rasagiline inhibit the breakdown of dopamine, they should not be taken with other medications that act on dopamine. They can, however, be taken with medications that act on norepinephrine.
What are the side effects?
Common side effects include nausea and vomiting, loss of appetite, diarrhea, problems urinating, cystitis (inflammation of the urinary bladder), back pain, muscle weakness or cramps in your legs or feet, and insomnia. Rasagiline may cause low blood pressure upon standing. Combined with levodopa, it might also increase hallucinations.