Family history of Parkinson's disease: does it run in families?

NHS inform describes Parkinson's disease as a condition in which parts of the brain become progressively damaged over many years. The NHS explains that it is caused by a loss of nerve cells in a part of the brain called the substantia nigra. These cells produce dopamine, a chemical that acts as a messenger between the parts of the brain and nervous system that help control and co-ordinate movement.

The loss of nerve cells is a slow process. The NHS says symptoms usually only start to develop when around half of the nerve cell activity in that area has been lost, which is one reason the condition can seem to appear suddenly in people who have had changes for some time.

Parkinson's UK says researchers do not yet know exactly why people get Parkinson's. For most people it is not inherited. In rare cases, a specific gene difference can cause it to be passed down in families. The NHS puts it similarly: the disease can run in families because of faulty genes passed from parent to child, but it is rare for it to be inherited in this way.

The NHS adds that a number of genetic factors have been shown to increase a person's risk, although how exactly these make some people more susceptible is unclear. So having a relative with Parkinson's may be a small risk factor, but the great majority of people with an affected relative will not develop it, and most people who do develop it have no relative with the condition.

If several members of your family, particularly across generations or at young ages, have had Parkinson's, it is reasonable to ask your GP about a referral to a specialist or clinical genetics service. The sources used for this page do not set out specific referral criteria, so that is a conversation to have with a clinician.

The NHS says some researchers feel environmental factors may increase the risk. It has been suggested that pesticides and herbicides used in farming, and traffic or industrial pollution, may contribute, but the evidence linking environmental factors to Parkinson's is inconclusive. This is not a basis for changing where you live or work, and no personal action has been shown to prevent the disease.

Age is also named as part of the picture by Parkinson's UK, alongside genes and environment.

The NHS explains that parkinsonism is the umbrella term for the symptoms of tremor, muscle rigidity and slowness of movement. Parkinson's disease is the most common type, but rarer types have a specific cause that can be identified.

• Drug-induced parkinsonism, where symptoms develop after taking certain medicines such as some antipsychotics and usually improve once the medicine is stopped.

• Other progressive brain conditions such as progressive supranuclear palsy, multiple system atrophy and corticobasal degeneration.

• Cerebrovascular disease, where a series of small strokes causes several parts of the brain to die.

The NHS says symptoms usually develop gradually and are mild at first, and that the order and severity differ for each person. The three main symptoms affect movement: a tremor that usually begins in the hand or arm and is more likely when the limb is resting, slowness of movement, and muscle stiffness.

Other symptoms can include balance problems, loss of sense of smell, which sometimes occurs several years before other symptoms, nerve pain, constipation, problems with peeing, problems sleeping, and mental symptoms such as depression and anxiety. NHS inform lists these too. None of them on its own means Parkinson's, and many have other causes.

The NHS says your GP will ask about your symptoms and medical history to decide whether to refer you to a specialist for further tests. NHS inform estimates that around 1 in 500 people are affected, which it puts at an estimated 127,000 people in the UK.

NHS inform also notes that Parkinson's disease does not directly cause people to die, but that the condition can place strain on the body and can make some people more vulnerable to serious infections. The charity Parkinson's UK is named by the NHS as a source of further information on parkinsonism and support.