What we know about Parkinson’s disease

Parkinson's disease is a progressive neurodegenerative disorder that occurs when nerve cells in the the brain become damaged or die, resulting in a decrease in dopamine - a chemical messenger essential for coordinating proper muscle movement.

Approximately 1 million people in the United States and 10 million around the world are living with Parkinson's, which is often accompanied by symptoms like tremors, stiff muscles, slowed movements, and problems with walking and posture - symptoms that tend to worsen and become more difficult to manage over time. Diagnoses of Parkinson's have nearly doubled in the U.S. over the past decade and are expected to continue rising.

Dr. Jeff Bronstein, a professor of neurology and director of the Levine Family Center for Movement Disorders at UCLA, studies the causes of Parkinson's, works to develop new therapies for patients,and is an expert on the management of the disease and other movement disorders.

For World Parkinson's Day, Newsroom presented Bronstein with some of the most commonly asked question about Parkinson's disease.

What causes Parkinson's disease?

We have made great progress in understanding the causes of Parkinson's disease, or PD. Approximately 5% of all cases of PD have a predominantly genetic cause, with a number of different genes that make up this 5%.

There are other genes that alter risk a little bit, but the majority of risk includes things that we can control, like environmental exposures and lifestyle choices. Examples include exposure to certain pesticides, air pollution and certain solvents. A Western diet - lots of meat, fried foods, sugars, etc. - is also associated with a higher risk for the disease, as are head trauma and lack of exercise. So, the cause of PD is a bit different for everyone who gets it, and it is due to a combination of genetic and environmental risk factors.

What are the early symptoms of Parkinson's disease? How quickly does the disease progress?

Ever PD patient is different, and the presenting symptoms are often different. Having tremors while at rest - tremors that are worse on one side of the body - is a common early symptom. "Dragging" a leg while walking and slowing down is another. Some people lose their facial expressions and their voice becomes softer. There are also several non-motor symptoms, such as anxiety and depression, constipation, low blood pressure, and cognitive problems, that occur in some patients.

In reality, many people have the first symptoms of PD decades before they exhibit one of those classic symptoms. For example, many people have what is called REM sleep behavior disorder, part of which is aggressively acting out dreams. Other have constipation, anxiety or the loss of smell years before they have the classic symptoms. It is important to remember that most people who get constipated or have anxiety will not get PD, but it does tell us that the disease begins long before we know someone has PD.

What is the most common way of treating Parkinson's disease?

We have fantastic treatments for most of the symptoms of PD, but we still don't have anything that slows the progress yet beyond exercise, which does slow the progression of symptoms. But there are no medications yet to treat PD itself, although there are several being tested now.

To treat the symptoms, we use several different formulations of levodopa (which supplements the dopamine in the brain deficient in Parkinson's) - this is still our best medication. And new levodopa delivery systems have made it even more effective. In a small group of patients, we can perform deep brain stimulation surgery or use a new technique called focused ultrasound to treat some symptoms that are not adequately controlled with medications.

We have several other medications to treat non-motor symptoms which are extremely important to recognize and treat. Depression is very common because PD lowers serotonin in addition to dopamine, so just as we replace the dopamine using levodopa, we replace the low serotonin with medications known as antidepressants. We have medications that can help control most motor and non-motor symptoms, although we do need medications that slow its progression.

Do Parkinson's symptoms come and go?

Symptoms can vary and fluctuate through someone's life. Other medical conditions can alter PD symptoms, and one's emotional state can alter the symptoms as well. Some symptoms can change over time, but it is a very variable disease.

Can Parkinson's symptoms ever be "reversed?"

Medications and surgeries can reduce symptoms dramatically, but they do not change the disease very much. It's the same as one someone has high blood pressure - medications can lower it, but if you stop the treatment, the high blood pressure returns. This is the same for PD.

Can diet help with Parkinson's disease?

Yes. Levodopa is the most important medication we have and is a naturally occurring amino acid. Proteins are made of amino acids, so if someone takes their levodopa with a high-protein diet, less levodopa gets absorbed, and it doesn't work as well. For this reason, we counsel patients to keep eating protein but to take the medication approximately one hour prior to meals.

In addition, in the long run, studies suggest that a Mediterranean diet lowers the risk of PD and might slow its progression. Some studies suggest a vegetarian diet may have the same benefits. So, a diet with less meat and dairy, fewer fried foods, and less sugars and one with more vegetables, fruits, whole grains, and plant-based oils like olive oil not only seems to help with PD - but with one's general health as well.

Can exercise help with Parkinson's disease?

Absolutely. Exercise is the only thing that has been clearly shown to improve quality of life for people with PD and likely slows the disease progression. It also helps with depression, constipation, heart health and brain health. There is no one perfect exercise, but it should be one you enjoy so that you keep doing it. A mixture of anaerobic (strengthening) exercise and aerobic exercise, such as walking or swimming, is recommended. But it is important to have fun in whatever activity you choose.

Is dementia a symptom of Parkinson's disease?

Some people do become more forgetful and have more trouble multitasking with PD, in a manner very similar to what you would see with normal aging. In most people, this doesn't reach the severity of dementia. With that said, with PD, there is an increased risk for dementia, which is why it is so important to stay both physically and mentally active to reduce this risk. Staying physically and mentally active also helps people without PD lower the risk of dementia - so everyone should try to keep a good diet, exercise, stay mentally and socially active, and get a good night's sleep to give them the best chance for a high quality of life as they age.

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