Parkinson's Disease (PD) is a progressive nervous system disorder that affects movement. Symptoms begin gradually, sometimes starting with a barely noticeable tremor in just one hand. Tremors are common, but the disorder also commonly causes stiffness or slowing of movement, walking disturbances and postural abnormalities.

In the early stages of PD, the face may show little or no expression, arms may not swing when walking, speech may become soft or slurred. Parkinson's Disease symptoms worsen over time.

Although PD cannot be cured, medications might significantly improve symptoms. Occasionally, the neurologist may suggest surgery to regulate certain regions of the brain and improve symptoms.

Parkinson's Disease signs and symptoms can be different for everyone. Early signs may be mild and go unnoticed. Symptoms often begin on one side of the body and usually remain worse on that side, even after symptoms begin to affect both sides.

Parkinson's signs and symptoms may include:

Tremor: A tremor or shaking is classically at rest, usually begins in a limb, often in the hand or fingers.

Slowed movement (bradykinesia): Parkinson's Disease is associated with slowness of movement, making simple tasks difficult and time-consuming. The steps may become shorter when walking. It may be difficult to get out of a chair and often feet are dragged on the floor with occasional freezing episodes.

Rigid muscles: Muscle stiffness may occur in any part of the body. The stiff muscles can be painful and limit the range of motion.

Impaired posture and balance: Posture may become stooped and balance difficulties are common.

Loss of automatic movements: In general, automatic unconscious movements are frequently affected and become more difficult. 

Speech changes: Speech may become soft, slurred and frequently hoarse.

Writing changes: It may become hard to write, and writing may appear small.

In Parkinson's Disease (PD), certain nerve cells (neurons) in the brain gradually break down or die. Many of the symptoms are due to a loss of neurons that produce a chemical messenger in your brain called dopamine. When dopamine levels decrease, it causes abnormal brain activity, leading to symptoms of Parkinson's Disease.

The cause of Parkinson's Disease  is unknown, but several factors appear to play a role, including:

Genes: Epidemiological studies have reported that the frequency of PD in Israel is twice that of the western world, with 2% of the population over the age of 60 years at risk for clinical PD. Mutations in the LRRK2 and GBA genes are the most significant risk mutations in PD, accounting for approximately 5% of the worldwide PD population and 35-40% in selected populations, such as Ashkenazi Jews and North African Berbers. In Israel, about 1/3 of patients with PD of Ashkenazi origin carry either the G2019S LRRK2 mutation or one of the 11 common mutations in the GBA gene. These mutations are present in nearly 10% of the general healthy Ashkenazi population in Israel, amounting to approximately 300,000 healthy individuals at risk. 

Environmental triggers: Exposure to certain toxins or environmental factors may increase the risk of later PD, but the risk is relatively small.

Researchers have also noted that many changes occur in the brains of people with PD, although it's not clear why these changes occur. These changes include:

The presence of Lewy bodies: Clumps of specific substances within brain cells are microscopic markers of PD. These are called Lewy bodies, and researchers believe these Lewy bodies hold an important clue to the cause of PD.

Alpha-synuclein is found within Lewy bodies: Although many substances are found within Lewy bodies, scientists believe an important one is the natural and widespread protein called alpha-synuclein (α-synuclein). It's found in all Lewy bodies in a clumped form that cells can't break down. This is currently an important focus among PD researchers.

Risk factors for Parkinson's Disease (PD) include:

Age: Young adults rarely experience PD. It ordinarily begins in middle or late life, and the risk increases with age. People usually develop the disease around age 60 or older.

Heredity: Having a close relative with Parkinson's Disease increases the chances to develop the disease.

Sex: Men are more likely to develop Parkinson's Disease than women.

Exposure to toxins: Ongoing exposure to herbicides and pesticides may slightly increase the risk of PD.

Parkinson's Disease (PD) is often accompanied by these additional problems, which may be treatable:

Thinking difficulties: People may experience cognitive problems (dementia) and thinking difficulties. These usually occur in the later stages of PD. Such cognitive problems aren't very responsive to medications.

Depression and emotional changes: People may experience depression, sometimes in the very early stages. Receiving treatment for depression can make it easier to handle the other challenges of PD.

Some may also experience other emotional changes, such as fear, anxiety or loss of motivation. Doctors may give these people medications to treat these symptoms.

Swallowing problems: People may develop difficulties with swallowing as condition progresses. Saliva may accumulate in the mouth due to slowed swallowing, leading to drooling.

Chewing and eating problems: Late-stage PD affects the muscles in the mouth, making chewing difficult. This can lead to choking and poor nutrition.

Sleep problems and sleep disorders: People with Parkinson's Disease often have sleep problems, including waking up frequently throughout the night, waking up early or falling asleep during the day.

People may also experience rapid eye movement sleep (REM) behavior disorder, which involves acting out dreams. Medications may help those sleep problems.

Bladder problems: PD may cause bladder problems, including being unable to control urine or having difficulty urinating.

Constipation: Many people with PD develop constipation, mainly due to a slower digestive tract.