Parkinson’s disease symptoms
Signs of Parkinson’s disease usually come on gradually and worsen over time. While most people with Parkinson’s develop symptoms after age 60, many people also develop them at a younger age.  Symptoms vary from person to person and include:

Problems with movement
Movement problems are the most common symptom of Parkinson’s disease. They include:

• Bradykinesia (slowness of movement): Parkinson’s disease causes muscles in your face, throat, and neck to move slowly. This slowness can make it difficult to talk, smile, and swallow, leading to drooling, choking, or coughing. Speech may sound monotonous and quiet. As muscles in your face move slowly, it becomes more challenging to make facial expressions.
• Stiff (tight) muscles: The muscles in your legs, arms, face, neck, and other parts of your body stiffen and contract (tighten). One of the most common early signs of Parkinson's is a reduced arm swing on one side of your body when walking.
• Problems with posture: Muscle changes cause many people to hunch over when standing or sitting. Posture changes can also affect balance, increasing the risk of falling. 
• Challenges with walking: As the disease progresses, walking can become increasingly difficult. People with Parkinson’s may bend forward at the waist, take small, shuffling steps, walk with their feet close together, and have trouble turning around. They may also experience “freezing,” while walking. This means they are suddenly unable to move, as if their feet are frozen to the ground.
• Trouble with daily tasks: Problems with movement and coordination can make it difficult to perform daily activities, such as brushing teeth, getting dressed, and standing up from a chair. Handwriting usually gets smaller and looks shaky.

Tremor
In addition to movement problems, many people experience tremor, or uncontrollable shaking. Tremor can be the first noticeable symptom of this disease, but some people with Parkinson’s do not develop it.

Tremor can happen when you are standing or sitting still (resting tremor). It may get better or stop when you move that body part. But sometimes the tremor will continue even when you are moving. Tremor might be worse when you are tired or experiencing physical or emotional stress.

Usually, tremor:

• Occurs first in a hand, arm, or leg on one side of your body, but can also affect your chin, lips, or tongue (over time, you may also experience tremor on the other side of your body)
• Goes away when you are sleeping
• Appears rhythmic, and when it affects your hands, it looks like you are rolling a tiny object around with your fingers (a movement called “pill-rolling tremor”)

Other symptoms
Parkinson’s disease can cause many different symptoms affecting your brain and body. They include:

• Anosmia: Many people lose their sense of smell entirely (anosmia) or experience decreased sense of smell (hyposmia). Because the senses of smell and taste are closely related, people with Parkinson’s can also lose their taste (ageusia).
• Changes in blood pressure: Standing up suddenly can cause a rapid drop in blood pressure and make you feel like you might faint. This is called orthostatic hypertension.
• Difficulty sleeping: People with Parkinson’s often have insomnia and other types of disordered sleep. The disease can cause people to move their limbs vigorously when they’re dreaming. Or their movement might be even more limited while they’re asleep, making it difficult to turn over in bed. Some people experience restless legs at night before they develop other symptoms. Sleep disruptions can cause excessive daytime fatigue, worsening other symptoms.
• Incontinence and constipation: Bladder and bowel problems are common symptoms of Parkinson’s disease. Many people find it challenging to urinate, or they may have an urgent need to go or are unable to control their bladder. Because the intestines cannot move contents through as effectively, constipation can result.
• Skin changes: Inflammation on the skin, especially on the face and scalp, can cause scales to appear. The scales can flake off, appearing like dandruff. This condition is called seborrheic dermatitis.

Mental health concerns and cognitive problems
Parkinson’s disease affects the brain, leading to a range of difficulties with mood, memory, reasoning, and thinking. These include:

• Cognitive decline: Parkinson’s can cause problems with memory and affect your ability to focus and think clearly.
• Dementia: Usually developing in the late stage of Parkinson’s, dementia and other cognitive problems can be severe. Parkinson’s-related dementia is a type of dementia with Lewy bodies (DLB).
• Depression: This is a common symptom of Parkinson’s disease. It can develop at any time and worsen as the disease progresses.
• Psychotic symptoms: People with Parkinson’s-related dementia are more likely to develop psychotic symptoms, including hallucinations. They may see things or hear voices that are not actually there. Or, they may suddenly think familiar people are dangerous or want to harm them.

The movement problems that occur with Parkinson’s disease result from damaged nerve cells in the part of your brain responsible for controlling movement. This part of the brain is called the basal ganglia. When the nerve cells become damaged and die off, they cannot produce dopamine. Dopamine is a chemical that is responsible for performing many functions in your body, including coordinating movement. Damage to these nerves also affects your sympathetic nervous system, the part of your body that controls blood pressure and heart rate.

Doctors do not know exactly what causes nerve cells in the basal ganglia to die. They believe it results from a combination of genetics and environmental factors. 

Parkinson’s disease risk factors

Certain factors can raise the chance of developing Parkinson’s. They include:

• Age: People over 60 are more likely than those in their 40s or 50s to develop the disease. Rarely, it occurs in younger people under the age of 30.
• Biological sex: Parkinson’s is more common in people assigned male at birth.
• Genetics: Researchers have discovered gene mutations (changes) associated with Parkinson’s. Talk to your doctor about genetic testing to determine if you have one of these gene changes.
• Environmental factors: Long-term exposure to toxins, such as those in pesticides, solvents, jet fuel, metals, herbicides, and other chemicals, increases the risk.
• Family history: While Parkinson’s disease does not seem to be inherited, people who have multiple family members with Parkinson’s do have a higher risk of the disease. This is especially true if they are closely related family members.
• Health history: Your risk of Parkinson’s disease is higher if you’ve had a traumatic brain injury (TBI). 

Preventing Parkinson’s disease
Although there is no way to prevent Parkinson’s disease, you may be able to lower your risk. Ensure that you’re getting enough fruits and vegetables, eat a balanced diet, and limit your exposure to toxins and chemicals. Talk to your doctor about an exercise plan. Physical activity is good for your overall health and may help reduce the risk of many health conditions and diseases, including Parkinson’s.

Your doctor will do a physical and neurological exam, asking you to move your hands, arms, and legs in certain ways. They will also ask about your symptoms, your family history and health history, and previous exposure to toxins.

Your doctor may recommend an imaging study to look for problems in the brain that might be causing symptoms. Types of imaging tests include:

• Magnetic resonance imaging (MRI): This test uses radio waves and magnets to create images of structures inside your brain.
• SPECT imaging with DaTscan™: This test looks at how your brain produces dopamine. Doctors use this imaging study to diagnose Parkinson’s disease and dementia with Lewy bodies.
• Computed tomography (CT) scan: This scan creates images of soft tissues and bones in your body by combining multiple X-rays.