Parkinson's Disease

Causes

• Genetics:
  • While most cases are sporadic (not inherited), genetic mutations are linked to a small percentage (5-10%) of cases, particularly early-onset Parkinson's.
  • Mutations in genes like LRRK2, PRKN (Parkin), PINK1, DJ-1, and GBA have been identified as increasing risk.
  • Even in sporadic cases, certain genetic variations may increase susceptibility.
• Environmental Factors:
  • Exposure to Toxins: Exposure to certain pesticides (e.g., rotenone, paraquat) or industrial chemicals has been associated with an increased risk in some studies, but definitive links are hard to establish.
  • Head Trauma: Some research suggests a link between head injuries and increased risk.
  • Rural Living: Some studies indicate a higher incidence in rural areas, possibly due to environmental exposures.
• Age: The greatest risk factor. Parkinson's disease typically develops around age 60 or older, with risk increasing with age. Early-onset Parkinson's occurs before age 50.
• Gender: Men are slightly more likely to develop Parkinson's disease than women.
• Lewy Bodies: The presence of Lewy bodies in the brain is a pathological hallmark of Parkinson's. These protein clumps disrupt brain cell function and are thought to contribute to neuronal degeneration.

Symptoms

• Motor Symptoms (Cardinal Symptoms - TRAP):
  • Tremor: Involuntary shaking, often starting in a limb, especially at rest (resting tremor). "Pill-rolling" tremor is characteristic.
  • Rigidity: Stiffness of the limbs and trunk, which can cause pain and limit range of motion.
  • Akinesia/Bradykinesia: Slowness of movement. This is a core symptom, leading to difficulty initiating movement, decreased facial expression (mask-like face), reduced arm swing while walking, and difficulty with fine motor tasks (e.g., writing becoming smaller - micrographia).
  • Postural Instability: Impaired balance and coordination, leading to falls. Often a later symptom.
• Other Motor Symptoms:
  • Shuffling gait.
  • Freezing of gait (sudden inability to move).
  • Dystonia (sustained muscle contractions causing twisting or repetitive movements or abnormal fixed postures).
  • Dysarthria (soft, monotonous, or slurred speech).
  • Dysphagia (difficulty swallowing).
  • Drooling.
• Non-Motor Symptoms (Can appear years before motor symptoms):
  • Loss of Smell (Anosmia): Often an early symptom.
  • Sleep Disorders: REM sleep behavior disorder (acting out dreams), insomnia.
  • Constipation.
  • Depression and Anxiety.
  • Fatigue.
  • Pain.
  • Cognitive Impairment: Problems with memory, attention, and executive function (can progress to dementia in later stages).
  • Urinary Problems: Urgency, frequency.
  • Orthostatic Hypotension: Drop in blood pressure upon standing, causing dizziness.

Diagnosis

• Medical History and Neurological Examination:
  • The doctor will ask about symptoms, their onset, progression, and impact on daily life.
  • Assessment of motor symptoms (tremor, rigidity, bradykinesia, postural instability) is key.
  • Checking reflexes, balance, coordination, and facial expressions.
• Response to Levodopa: A significant and sustained improvement in motor symptoms after taking levodopa (a Parkinson's medication) often supports a diagnosis of Parkinson's disease. This is sometimes called a "levodopa challenge test."
• Imaging Tests (mainly to rule out other conditions):
  • MRI (Magnetic Resonance Imaging) of the Brain: Used to rule out other conditions that can cause similar symptoms, such as stroke, brain tumors, or hydrocephalus. It typically appears normal in early Parkinson's disease.
  • DaTscan (Dopamine Transporter Scan): A specialized SPECT scan that can help differentiate Parkinson's disease and other parkinsonian syndromes from essential tremor and drug-induced parkinsonism. It measures the density of dopamine transporters in the brain.
• Blood Tests: To rule out other conditions that may present with similar symptoms, such as thyroid disorders or vitamin deficiencies.

Treatment

• Medications:
  • Levodopa (with carbidopa): The most effective medication for controlling motor symptoms (bradykinesia, rigidity). Carbidopa prevents levodopa breakdown before it reaches the brain. Often combined as Sinemet.
  • Dopamine Agonists: Mimic the effects of dopamine in the brain (e.g., pramipexole, ropinirole, rotigotine patch). Can be used alone or with levodopa.
  • MAO-B Inhibitors: Prevent the breakdown of dopamine in the brain, increasing its availability (e.g., selegiline, rasagiline, safinamide). Often used in early Parkinson's or as an adjunct.
  • COMT Inhibitors: Extend the effect of levodopa by blocking an enzyme that breaks it down (e.g., entacapone, opicapone). Used with levodopa.
  • Amantadine: Can help with dyskinesia (involuntary movements) that can occur as a side effect of levodopa.
  • Anticholinergics: (e.g., trihexyphenidyl, benztropine) May help reduce tremor and rigidity, more often used for younger patients.
  • Pimavanserin (Nuplazid): For Parkinson's disease psychosis.
• Deep Brain Stimulation (DBS):
  • A surgical procedure for advanced Parkinson's disease that is not adequately controlled by medications.
  • Electrodes are surgically implanted into specific areas of the brain and connected to a pulse generator (like a pacemaker) to deliver electrical impulses that help regulate abnormal brain activity.
• Other Therapies:
  • Physical Therapy: To improve balance, gait, flexibility, and strength.
  • Occupational Therapy: To adapt daily activities and environments to maintain independence.
  • Speech Therapy: To improve voice volume, clarity, and swallowing difficulties (e.g., LSVT LOUD program).
  • Dietary and Nutritional Support: To address constipation, dysphagia, and medication interactions.
  • Psychological Counseling: To manage depression, anxiety, and other non-motor symptoms.
• Lifestyle Adjustments:
  • Regular exercise, including aerobic activity, balance exercises (e.g., tai chi), and strength training.
  • Good sleep hygiene.
  • Stress management.
  • Staying hydrated.

Living Well With Parkinson's Disease

What determines how well the treatments above work day to day is timing, food, exercise, the non-motor symptoms that get less attention, and a short list of common medications that must be avoided.

Levodopa: timing and protein

Carbidopa-levodopa works best taken at the same times every day, about half an hour before meals, because protein competes with it for absorption; shifting most of the day's protein to the evening meal helps people who notice doses failing after lunch. A late dose can mean an hour of being unable to move, which is why a printed schedule goes to the hospital with every admission. Wearing off before the next dose and involuntary movements at the peak are expected after some years and are managed by adjusting the schedule and adding other agents, not by stopping.

The medications that make Parkinson's worse

Metoclopramide and prochlorperazine for nausea, promethazine, and nearly all antipsychotics block dopamine and can cause days of severe stiffness; among antipsychotics only quetiapine, clozapine, and pimavanserin are generally acceptable. Every new prescription, especially from an emergency department, is checked against that list.

Exercise is a treatment, not a suggestion

Vigorous aerobic exercise several times a week, along with balance and strength work such as tai chi, boxing programs, or physical therapy, improves motor function and is the intervention most consistently linked to slower decline. In the Florida heat that means early mornings, air-conditioned classes, or the pool, particularly because Parkinson's impairs sweating and worsens orthostatic hypotension; our chronic conditions in the Florida heat guide covers the precautions. Falls are the main cause of injury; the fall prevention guide applies doubly here.

The non-motor symptoms that respond to treatment

Chronic constipation precedes diagnosis by years and slows levodopa absorption, so it is treated actively with fluids, fiber, and polyethylene glycol. Acting out dreams, depression, and daytime sleepiness are common and treatable, and swallowing difficulty is assessed by speech therapy early because aspiration pneumonia is a leading cause of death. Memory change is watched for, since dementia develops in a substantial share of people after many years and changes which medications are safe.

What it is confused with

A tremor that appears when holding a cup rather than at rest is usually essential tremor, and slowness that began after starting a dopamine-blocking drug is drug-induced parkinsonism that resolves when it is stopped. Our neurologic team coordinates care with the movement disorder specialist and manages the medical problems around it. NINDS and the Parkinson's Foundation publish patient guidance.

If your levodopa is wearing off before the next dose, or you have not had a fall risk assessment, schedule a visit.