Parkinson's disease: an animated, cited guide

This page needs JavaScript for its animations. The outline and key answers are below, and every claim in the full version carries a numbered citation.

Not medical advice. Parkinson's Companion is an educational synthesis of published literature. It does not replace a clinician.

What is in it

What Parkinson's is Parkinsonism versus Parkinson's disease, who it affects, the numbers.
The dopamine pathway Substantia nigra to striatum, the go and brake loops, and what losing dopamine does.
Alpha-synuclein and Lewy bodies From a small synaptic protein to a Lewy body, and how it may spread.
How it spreads: Braak stages Six stages from the brainstem to the cortex, and the body-first debate.
Genes and inheritance LRRK2, GBA1, SNCA and parkin, founder populations, and what a test means.
Before the tremor Dream enactment, smell, constipation and the prodromal criteria.
Stages and symptoms Hoehn and Yahr, motor and non-motor symptoms, and how fast it moves.
Diagnosis and the MDS criteria The clinical criteria as a calculator, DaT scans and synuclein tests.
The differential Essential tremor, drug-induced parkinsonism, MSA, PSP and Lewy body dementia.
Levodopa and carbidopa From the pill to the striatum, step by step.
Levodopa over time Wearing-off, dyskinesia, the narrowing window and what smooths it.
The other medicines Agonists, MAO-B and COMT inhibitors, amantadine and the order of use.
Deep-brain stimulation Targets, the stimulation field, the beta rhythm and what the trials found.
Beyond movement Mood, hallucinations, dementia, sleep and blood pressure.
Risk and protection Pesticides, solvents, head injury, smoking, coffee and exercise.
Living with Parkinson's Exercise, therapy, falls, speech, work, caregiving and the end of life.
Nursing care Medicines on time, drugs to avoid, swallowing, assessment, documentation.
Toward a cure Synuclein antibodies, GLP-1 drugs, LRRK2 and GBA1, cells and genes.
History and people From James Parkinson's 1817 essay to the synuclein test.
Flashcards and mnemonics Flip cards by topic.
Quiz Questions with explanations.
Glossary Every term, searchable.
Sources Every reference behind the guide.

Part 1 · The disease

What Parkinson's is

Parkinsonism is a pattern of movement signs, not one disease. Several conditions can cause it, and Parkinson's disease is the most common of them. Press play to build the picture, then see the signs up close and how the odds change with age.

Timeline

Schematic. Circle sizes in the umbrella are not to scale; the grid of 100 squares and the bar are. The small traces illustrate the definitions; they are not recordings.

The signs, up close

A clinician looks for these signs on examination. Pick one to see what the definition means in movement.

Sign

Time

Schematic. The movements and traces illustrate the published definitions; they are not patient recordings.

Who it affects: age and sex

Show

Age

New cases of Parkinson's disease per 100,000 person-years, Olmsted County, Minnesota, 1976 to 2005 (Savica 2016). Each bar spans its age band.

The numbers, and where sources disagree

Counts depend on the year, the method and the population. Each card names its source so the figures can be compared fairly.

Worldwide, now

Over 8.5 million

people had Parkinson's disease in 2019, according to the WHO fact sheet. Prevalence has doubled in the past 25 years. In 2019 it caused 5.8 million disability-adjusted life years, up 81% since 2000, and 329,000 deaths, up more than 100%. ³⁷⁷

WHO fact sheet dated 9 August 2023.

Worldwide, 1990 to 2016

2.5 → 6.1 million

The Global Burden of Disease study counted 6.1 million people with Parkinson's in 2016 (95% UI 5.0 to 7.3), against 2.5 million in 1990. Age-standardised prevalence still rose by 21.7%, so the increase is not explained by ageing alone. Parkinson's caused 211,296 deaths in 2016. ¹²⁰

The authors attribute the rise mainly to more older people, with possible contributions from longer disease duration and environmental factors. ¹²⁰

Forecasts

12 or 25 million?

Dorsey and colleagues call Parkinson's "the fastest growing neurological disorder in the world" and project a rise from over 6 million in 2015 to over 12 million by 2040, or above 17 million with longer lifespans, less smoking and industrialisation. ⁸⁵ A 2025 GBD 2021 model projects 25.2 million in 2050 (95% UI 21.7 to 30.1), a 112% increase from 2021: 89% of the growth from ageing, 20% from population growth and 3% from changing prevalence. ³⁴⁷

Sources differ The projections use different GBD rounds, base years and assumptions. Both name ageing as the main driver. ^85,347

North America

About 680,000

people with Parkinson's in the US in 2010, from a prevalence of 572 per 100,000 among people aged 45 and over. The model projected about 930,000 in 2020 and 1,238,000 in 2030; the authors call these minimum estimates. ²¹¹

Across five North American data sources in 2012, yearly incidence at 65 and over ranged from 108 to 212 per 100,000. ³⁸⁰ In Kaiser Permanente data, adjusted incidence was 16.6 per 100,000 in Hispanic, 13.6 in non-Hispanic White, 11.3 in Asian and 10.2 in Black members. ³⁵⁷

Israel

1%, 2%, 3%

of people aged 50, 60 and 70 and over had Parkinson's in a drug-tracer study of an Israeli health maintenance organisation covering about a quarter of the population (1998 to 2008). Incidence was stable at about 33 per 100,000 a year; prevalence rose from 170 to 256 per 100,000; the mean age at the first anti-parkinsonian prescription was 69. Men aged 50 and over had higher prevalence (RR 1.38) and incidence (RR 1.45). ⁶⁰

Against the trend In the Clalit registry (2002 to 2021), age-adjusted incidence fell from 57 to 20.3 per 100,000, faster in women than in men. The authors suggest better diagnosis and better health and environmental conditions. Elsewhere, incidence in men rose over 30 years in Olmsted County. ^21,314

Men and women

About 1.4 to 1

The GBD male to female ratio of age-standardised prevalence was 1.40 in 2016 and 1.37 in 1990. ¹²⁰ It is projected to rise from 1.46 in 2021 to 1.64 in 2050. ³⁴⁷

For new cases the gap is wider. Men to women incidence rate ratios at 65 and over were 1.66 (Ontario), 1.69 (Medicare), 1.77 (Kaiser) and 2.57 (Rochester) in 2012. ³⁸⁰ A meta-analysis found higher incidence in men in every age group, significant at 60 to 79. ¹⁴⁵

Early onset

21 to 50

The MDS task force recommends "early-onset" rather than "young-onset" Parkinson's, partly to avoid age-related stigma, and defines it as onset after 21 and before 50. Onset before 21 is conventionally called juvenile parkinsonism. Published cutoffs have ranged from 40 to 60. ²²⁷

Only 4% of Kaiser Permanente cases began before 50. ³⁵⁷ Genes matter more at younger onset: see Genes and inheritance.

Exam hookParkinsonism = bradykinesia plus rest tremor and/or rigidity (MDS 2015); postural instability is not part of the core definition. Parkinson's disease was 42% of new parkinsonism in Olmsted County, with drug-induced parkinsonism second at 20%. ^40,288