The main symptoms of Parkinson's – tremor, rigidity and slowness of movement – are also the main symptoms of a number of conditions that are grouped together under the term parkinsonism.
Idiopathic Parkinson's disease - or Parkinson's - is the most common type of parkinsonism. Unlike some other forms which have specific causes it is not known why idiopathic Parkinson's occurs. Idiopathic means that the cause is unknown.
The main symptoms of idiopathic Parkinson's are tremor, rigidity and slowness of movement.
The specialist confirmed I have Parkinson's. Now I'm having treatment and I'm feeling much better.
Anne, diagnosed in 2009
Symptoms and the rate at which the condition progresses vary from person to person. This can make diagnosis difficult.
An early diagnosis means that treatment for Parkinson's can begin sooner, which may be more effective.
Doctors may diagnose idiopathic Parkinson's by seeing if there is a response to Parkinson's medication. If symptoms improve, your specialist may confirm an idiopathic Parkinson's diagnosis.
Read more on how Parkinson's is diagnosed in our Diagnosing Parkinson's information sheet.
Vascular parkinsonism is one of the atypical forms of parkinsonism.
It affects people with restricted blood supply to the brain - usually older people who have problems with diabetes. People who have had a stroke may experience vascular parkinsonism.
Symptoms of vascular parkinsonism may include difficulty speaking, making facial expressions or swallowing.
Other signs can include problems with memory or confused thought, cognitive problems and incontinence.
Like Parkinson's, vascular parkinsonism is a progressive condition, with symptoms developing and changing over time.
A small number (around 7%) of people diagnosed with parkinsonism have developed their symptoms following treatment with particular medication.
Drugs - known as neuroleptic drugs - used to treat schizophrenia and other psychotic disorders block dopamine. These drugs are thought to be the biggest cause of drug-induced parkinsonism.
The symptoms of drug-induced parkinsonism tend to be static. Only in rare cases do they change in the manner that the symptoms of Parkinson's do.
Most people will recover within months, and often within hours or days, of stopping the drug that is the cause.
Our Drug-induced parkinsonism information sheet lists the drugs that are known to cause the condition.
My wife's clarity of mind can vary drastically. But when she has a good spell, these times are of great value to me.
David, who's wife has dementia with Lewy bodies
Symptoms differ slightly from Parkinson's and include problems with memory and concentration, attention, language and the ability to carry out simple actions.
People who have dementia with Lewy bodies commonly experience visual hallucinations and some Parkinson's-type symptoms, such as slowness of movement, stiffness and tremor.
Dementia with Lewy bodies is also a progressive condition, which means that the symptoms can become worse over time. Currently, there is no cure or treatment for the condition.
There is no conclusive evidence that Parkinson's is a hereditary condition that can be passed on within families, apart from in exceptionally rare cases.
It is thought that although it is not directly inherited, some people may have genes that increase the possibility of developing Parkinson's.
People who have genes that are prone to Parkinson's may be more likely to develop the condition when combined with other factors, such as environmental toxins or viruses.
At present, it is estimated that up to 5% of people with Parkinson's may have a genetic cause.
The role genetics may play in the development of Parkinson's is currently the subject of much research.
Our Inherited Parkinson's and genetic testing information sheet gives more information.
You can also read about research we're funding into the causes of Parkinson's.
The term early onset Parkinson's is used when people are diagnosed under the age of 40.
Juvenile Parkinson's is a term used when the condition affects people under the age of 20.
Read more in our Juvenile Parkinson's information sheet.
A diagnosis indicating that someone doesn't have Parkinson's but does have another unknown condition can be unsettling.
In some cases the symptoms that allow doctors to make a specific diagnosis appear slowly, over a longer period of time, as the condition develops.
If tremor is the only symptom and it seems different from the tremor found in Parkinson's, then a person may be diagnosed with essential tremor, dystonic tremor, indeterminate tremor or atypical tremor.
Some symptoms may lead to a diagnosis of Multiple System Atrophy (MSA), Normal Pressure Hydrocephalus or Progressive Supranuclear Palsy (PSP).
There are organisations that offer help and support for people diagnosed with these conditions and their families:
Information last updated August 2014. Next update available August 2017.