Parkinson's disease is a progressive neurological disorder that affects motor function. The disorder results in tremors, slow and interrupted movements (bradykinesia), and rigidity. The exact causes of Parkinson's disease are unknown, but people older than 60 and men are more likely to develop it

Types of Parkinson's Disease

Parkinson’s disease is classified into different types based on the cause of symptoms:

  • Idiopathic Parkinson’s Disease:
    The majority of cases are idiopathic, meaning no known cause can be identified. Diagnosis typically occurs when cardinal signs like tremors and bradykinesia appear without the presence of another medical condition, environmental exposure, genetic predisposition, or medication use. This type commonly affects those over the age of 60.
  • Early-Onset Parkinson’s Disease:
    This form appears in younger individuals, usually before the age of 55. It is rare, representing only about 5% to 10% of cases. It tends to have a slower onset, preserved cognitive function, and a stronger motor response to medication.
  • Familial Parkinson’s Disease:
    Some rare cases are inherited. Researchers have identified around 20 specific genetic mutations that can cause Parkinson’s symptoms. These mutations account for about 5% to 10% of cases and may also contribute to early-onset forms.

Parkinson’s Disease Symptoms

Symptoms can vary widely. Parkinson’s disease has four cardinal signs and many additional motor and non-motor symptoms.

Cardinal Signs

The four cardinal signs are:

  • Bradykinesia:
    Slowed or interrupted movement that causes weakness, poor coordination, and difficulty with motor control.
  • Postural Instability:
    Difficulty maintaining an upright posture, leading to imbalance and an increased risk of falls.
  • Rigidity:
    Stiffness and tension in the muscles, often affecting one side more than the other and causing discomfort.
  • Tremor:
    Uncontrollable shaking, typically while at rest, that progressively worsens over time.

Other Motor Symptoms

Additional motor symptoms can include:

  • Shuffling gait with short, awkward steps
  • Blurred vision
  • Excessive drooling
  • Festination (involuntary speeding up of repetitive movements)
  • Freezing during repetitive movements
  • Impaired upward gaze and eye movement
  • Difficulty chewing (dysphagia)
  • Speech impairments
  • Stooped or angled posture

Non-Motor Symptoms

Parkinson’s disease can also present with a range of non-motor symptoms, sometimes before the motor symptoms:

  • Autonomic dysfunction (dizziness, constipation, urinary issues, erectile dysfunction)
  • Skin disorders
  • Fatigue and excessive daytime sleepiness
  • Hallucinations and psychosis
  • Cognitive impairment and dementia
  • Mood disorders such as depression and anxiety
  • Loss of smell and taste (olfactory dysfunction)
  • Pain
  • Sleep disorders

Causes of Parkinson’s Disease

Parkinson’s disease is caused by the degeneration of neurons in the substantia nigra, a region of the brain that regulates movement. These neurons produce dopamine, a key neurotransmitter. As dopamine and norepinephrine levels fall, movement control becomes impaired.

The exact cause of this neuronal degeneration is unknown. Genetic mutations may directly cause a small number of cases, while environmental exposures are believed to contribute to susceptibility. Most researchers agree that Parkinson’s arises from a combination of genetic and environmental factors.

Risk Factors

Several factors increase the risk of developing Parkinson’s disease:

  • Age:
    Being over 65 significantly raises the risk.
  • Environmental Exposure:
    Living in rural areas, farming exposure, high levels of dietary iron, air pollution, and vitamin D deficiency are all associated with higher risk.
  • Genetics:
    Having a family history of Parkinson’s or known gene mutations increases susceptibility.
  • Sex:
    Men are slightly more likely than women to develop the disease.

Diagnosis

There is no single test for Parkinson’s disease. Diagnosis relies on medical history, symptom assessment, and neurological exams. Doctors typically evaluate:

  • Gait and walking ability
  • Balance (pull test)
  • Ability to perform repetitive movements
  • Muscle rigidity
  • Presence of spontaneous or resting tremors

Imaging studies like MRI, DaTScan, and PET scans may help rule out other conditions. Olfactory tests and genetic testing may also be used when necessary.

Parkinson’s Disease Treatment

While there is no cure, treatment aims to control symptoms and maintain quality of life.

Medications

The primary approach involves medications that enhance dopamine activity:

  • Levodopa-carbidopa (e.g., Sinemet, Rytary)
  • Amantadine (often added to other medications)
  • Anticholinergics (e.g., trihexyphenidyl, benztropine)
  • Non-ergot dopamine agonists (e.g., pramipexole, ropinirole, rotigotine patch)
  • MAO-B inhibitors (e.g., selegiline, rasagiline, safinamide)

Deep Brain Stimulation

For severe cases or medication-resistant symptoms, deep brain stimulation (DBS) can be an option. Electrodes are implanted in the brain and connected to a device in the chest that delivers electrical stimulation to targeted areas.

Physical Therapy

Physical therapy can improve gait, strength, balance, and fine motor skills. Speech therapy may help if communication abilities decline.

Lifestyle Changes

Recommended changes include:

  • Adopting a diet rich in vitamins, minerals, fiber, and antioxidants
  • Reducing intake of processed foods and sugars
  • Practicing yoga, stretching, and aerobic exercises
  • Stress management techniques like meditation and warm baths
  • Massage therapy to ease muscle rigidity

Prevention

Since the cause of Parkinson’s disease is unknown, it cannot currently be prevented. However, regular aerobic exercise and adherence to a Mediterranean diet may slow the disease's progression. Limiting dairy and alcohol consumption and increasing caffeine intake may also offer some protective benefits.

Related Conditions

Parkinson’s disease is associated with other health concerns:

  • Anemia:
    People with anemia have a higher risk of Parkinson’s disease.
  • Dementia:
    Cognitive decline affects a significant number of people with Parkinson’s, especially in advanced stages.
  • Depression:
    Common among those living with the disease, influenced by both emotional and physiological factors.
  • Diabetes:
    There may be a link between diabetes and Parkinson’s, although more research is needed.
  • Hypertension:
    High blood pressure is commonly found in people with Parkinson’s.

Living with Parkinson’s Disease

Parkinson’s disease is chronic and progressive. Although not directly fatal, it greatly affects independence and life expectancy, with most individuals becoming disabled within 10 years of diagnosis.

Strategies for coping include:

  • Connecting with patient advocacy organizations
  • Seeking support from family, friends, and caregivers
  • Participating in support groups or online communities for advice and emotional support