Parkinson's Disease (PD)

Parkinson's disease (PD) is a neurodegenerative disorder that causes uncontrolled or unintended movements of the body

PD occurs as a result of progressive damage or death to nerve cells (neurons) – in an area of the midbrain called the substantia nigra pars compacta, which produces Dopamine. This neurotransmitter is crucial for movement and motor function, mood / emotions, behaviors, and cognitive functions, including memory. A decrease in Dopamine leads to a disruption of signals regulating these functions.

In more detail

The neurotransmitter Dopamine is a chemical messenger that transmits signals between the par compacta (a subdivision of the substantia nigra of the mid-brain) and the corpus striatum (largest part of the subcortical basal ganglia), a critical component of motor and action planning, decision making, motivation, and reward systems, serving as primary input to the rest of the basal ganglia, having a key role in the choices of movement or behaviors to execute.

Who gets PD?

1 million people in the U.S are affected by PD( ~2% of those over 65 years old) and more than 10 million worldwide.

Symptoms

Tremors. Usually beginning in the hand, sometimes the foot or jaw. PD tremor is characterized by a back-and-forth shaking. Predominant when hand at rest or person is stressed. A particular symptom is that the affected person rubs their thumb and forefinger together. Shaking does not usually occur during sleep.
Rigidity. Muscle tightness resists movement
Slowness of movement (bradykinesia). Can make simple tasks take longer
Poor balance / postural changes. Increases risk of falling. Leaning forward whilst walking, reduced arm-swinging.

Other symptoms may develop including problems sleeping, oilier or drier skin, difficulty speaking (quietly, hesitation, slurring, too fast), bladder / bowel / sexual dysfunction, dementia, cognitive problems (such as dementia, memory, slow thought-process), dizziness due to sudden drop of blood pressure getting up or down, fatigue, muscle pain / contractions

Causes

Most cases do not run in families, but some cases may involve genetics
Affect men more than women
Most likely cause is environmental exposure to toxins
Researchers have detected damage from oxidative stress
Viral infections are a substantial risk factor and possible trigger or potential cause of PD. A common, normally considered harmless virus, human pegivirus (HPgV), brain infection was found (in post-mortem analysis) in 50% of people with Parkinson’s disease, but not in those without the condition. 2025 study.

Parkinsonism was observed after the 1918 epidemic of encephalitis lethargica, also after flaviviral encephalitis (caused by West Nile virus), St. Louis Encephalitis virus, Japanese Encephalitis B virus, and HIV worsened on progression to AIDS and alleviated with antiretroviral therapy.

Mainstream treatments

Mainstream medicine offers no cure for Parkinson’s – with treatments focusing on:

Replacing missing Dopamine in the brain with:

Dopamine precursors, mainly Carbidopa-Levodopa (L-dopa) which converts to Dopamine only when in the brain and unlike Dopamine, L-dopa can cross the blood brain barrier but does have unpleasant side-effects)
Dopamine agonists. Drugs that mimic Dopamine, such as apomorphine, pramipexole, ropinirole, and rotigotine.
MAO-B inhibitors. Block breakdown of Dopamine in the brain. E.g. selegiline and rasagiline
COMT inhibitors. Also block Dopamine breakdown, prolonging L-dopa effects.

Controlling abnormal movements using drugs. E.g. drugs that reduce production or uptake of the neurotransmitter acetylcholine. However, these treatments to not replace damaged neurons or stop progression of PD.